Free online temperature conversion tools

Temperature degrees conversions of Fahrenheit (°F), Celsius (°C), Kelvin (K), Rankine (°R).

Enter the temperature in one of the text boxes and press the Convert button:


Temperature conversions

What is temperature?

The degree of hotness and coldness is defined as temperature. This degree or measurement of hotness or coldness can be expressed in different standardized units such as Fahrenheit (°F), Celcius(°C) , or Kelvin (K).

A basic temperature converter can easily help you convert temperature values from one unit to another. We will talk about details regarding temperature conversion online later in this article. First, let's study temperature and its relation to other scientific terms and properties.

Heat VS Temperature

Temperature is measured in terms of the transfer of heat from a hotter body to a colder body. The heat is a form of energy always flowing toward bodies with cooler temperatures. The colder bodies are said to be having lower temperatures while hotter bodies are said to be having higher temperatures. There is a difference in heat and temperature but people often confuse the two.

Heat is a form of energy and it transfers from hotter to colder bodies and is measured in Joule (J). Whereas temperature is the measure of how much a body is hot or cold. It has units other than Joule.

The more heat energy an object has, it automatically means that it has a higher temperature. But we should not confuse them together. When a hotter system or body gets in contact with a colder system it gets some of its energy transferred to the colder body thus the temperature changes for both. Heat is mostly defined as an overall motion in the molecules of a system fueled by its kinetic energy. It is a firm of energy and measures the average energy of a body in degrees from its temperature.

What is a Thermodynamic System?

Thermodynamics is a branch of physics dealing with the properties of heat and how it changes to and from other energy forms or types. Originating from the Greek word thermé meaning heat and dynamics meaning force, it is concerned with heat as a force and how it interacts with different substances. It is a science behind how hotter bodies become cold due to heat change and how their temperature varies according to the amount of thermal energy a body has.

A thermodynamic system is a body of matter confined in a space of interest separated by boundaries. When we consider a thermodynamic system, heat transfer and its types is an important subcategory to understand. Heat transfer methods such as conduction, convection, radiation, etc. are important to understand the workings of a thermodynamic system.

How Kinetic Energy Works in a Thermodynamic System?

If we study temperature in-depth, we will understand that all bodies have kinetic energy in their molecules while they are constantly in motion. When this kinetic energy of inner particles in a body is measured as an average physical quantity, the temperature can be expressed. It is called a physical quantity because it can be measured and felt.

In more scientific terms, the temperature is an ability of a physical system to transfer heat energy to another physical system. The faster the particles in an object move, the higher its temperature becomes and the hotter it gets.

For example, when you boil water, its molecules start moving and you see bubbles start to form as the water gets hotter and the temperature goes higher. As the temperature goes high and further heat is provided, liquid water changes its state and takes a gas form, the heat supplied to it causes the molecules to lose their bonds and liberate the container in the form of vapor.

Thermal Expansion

The question that comes to mind is why bodies at lower temperatures have less heat? Simple, it is because at a lower temperature, particles inside a body move slowly and this slow pace causes them to collide less frequently.

The collision of moving particles is the main cause of heat and an increase in temperature. If the particles are moving slowly, there will be less friction and thus the body will be colder. At a lower temperature, objects change their shape, harden, shrink and freeze. Whereas, at higher temperatures, the bodies expand due to thermal expansion.

A fun fact regarding this phenomenon is how the Eiffel tower gets an expansion in its metallic, iron brackets due to thermal energy at high temperatures in summers. The tower expands and increases in size just a few centimeters more and tilts away from the scorching heat of the sun. The tower, in normal seasons, stands at 324 meters in height yet this increases up to 17 centimeters when the sun beats down on it.

Types of Heat Transfer

Heat transfers in substances according to their state and form. Heat transfer mechanisms in bodies are either via thermal conduction or diffusion, thermal convection, or thermal radiation. Heat also transfers when a body of matter changes its phase. This sort of heat transfer is called transfer by phase transition.

Metals are good conductors of heat and electricity. Thermal conduction occurs concerning the heat transfer method called conduction that happens when molecules with faster kinetic energy transfer heat to the slower ones. The process continues until heat transfers from one end of a linear material rod to another. Conductors and insulators have strong applications in the field of thermodynamics.

Conduction occurs in solids mostly and convection is more common in fluids. In fluids, hotter molecules rise and become less dense due to the release of heat while colder molecules sink and become denser. On the other hand, radiation occurs when heat energy is emitted as electromagnetic waves from the moving of subatomic particles inside an element.

Thermal Conductivity

Thermal conductivity is an important property of materials that permit heat to pass through them such as metals. The thermal conductivity of any substance is defined as the amount of its ability to conduct heat. When a body has a high measure of thermal conductivity heat transfer occurs at a higher rate and if a body has a low measure of thermal conductivity, heat transfer occurs at a lower rate. It is denoted by the k-value.

The thermal conductivity mechanism involves the transfer of heat from higher temperature particles to lower temperature particles in a body and continues to happen until thermal equilibrium is reached. Thermal resistivity is the reciprocal of thermal conductivity and is the ability of an object to resist heat. The speed at which the heat transfers depends upon the temperature quotient and the thermal properties of a body. The thermal conductivity equation is defined as follows:

k =Q∗L/A(T2−T1)

Where k denotes Thermal Conductivity and sometimes lambda (λ) is also used for the same purpose.

Q is the heat transfer amount through a substance in Joules/sec.

L is the distance between two isothermal (i.e. where the temperature of a system remains constant) planes.

A is the area of the system surface measured in square meters.

(T2-T1) or Delta T is the temperature difference in Kelvin.

Specific Heat

As the liquid state of water has a higher heat capacity due to the molecules moving faster. The kinetic energy of the particles in liquids is greater therefore they absorb more heat. When talking about heat and temperature, specific heat is mentioned in these two scientific terms. Specific heat is defined as the amount of heat energy, measured in joules, required to increase the temperature of 1 gm of mass by 1 Kelvin or Celsius degree.

For unit conversion from Kelvin to Celsius or vice versa, an online temperature conversion calculator can be used. Different elements in our surroundings have different heat capacities or specific heat quotients. The units of specific heat are most commonly used as 1 calorie per gram per Kelvin or Celsius degree.

Latent Heat

Heat is the decisive catalyst in changing the phases of substances. As matter has 4 natural states that are; solid, liquid, gas, and plasma, heat is required to let matter change its shape from solid to liquid and from liquid to gas. Similarly, if you want to change gas to liquid or liquid to solid, the temperature should be decreased instead of an increment. Latent heat is also known as the heat of transformation or latent heat energy. It is the hidden heat of a thermodynamic system that is absorbed or released mostly during a first phase change without changing the temperature of that system.

Latent energy is supplied or extracted from a body to stimulate a phase change of matter. Scottish scientist, Joseph Black introduced this Latin term to express the heat transfer process upon supplying hidden heat where the volume of a body changed while the temperature remained constant. Contrastingly, if a heat transfer happens and the temperature of a body also changes then it would be known as sensible heat. Two main forms of latent heat are:

  • Latent heat of fusion (melting)
  • Latent heat of vaporization (boiling)

The melting or boiling depends upon the direction of energy flow. If it is from solid to liquid, melting happens. If the energy flows from liquid to gas, vaporization occurs as the result of a boiling process.

In these processes, the change is endothermic meaning that heat is absorbed. Such as when water evaporates, the molecules require energy to overcome the binding forces. The boiling causes an increase in the kinetic energy and collision starts until the heat is absorbed enough to let the molecules evaporate. When the energy is released instead, the change is exothermic.

Why are Temperature Conversion Online Tools Necessary?

Imagine you are a science graduate constantly in tune with the practical application of scientific formulas and equations. If you are doing a post-graduate diploma, working on your research thesis and calculations are always needed in your line of work.

Scientific units and metrics are standardized, however, you still require frequent conversions according to changes in facts and figures, numeric data, addition or elimination of different variants, and a plethora of other factors. As a research student or a lab engineer or a university professor working on a lecture preparation or marking quizzes, etc. whatever position you are in if you are related to science in some way or other you have to keep yourself informed and focused.

The online revolution has made things easier and accessible. Now the advancement of handheld devices and mobile-embedded calculators have changed the world of accounts and statistics. People no longer have an urge to reach out to the nearest calculator for any sort of manual computation they need. They simply have calculating tools and apps downloaded on their devices that they can use efficiently without a hassle.  

As a cherry on top, Artificial Intelligence based systems have made things far more easier and handy. If you are busy typing away your thesis and require some fast calculation to cross-check any facts, you can just use a voice recognition feature to state your equation for calculation. These sorts of tech reforms have made scientific computation an easy task indeed.

Some units for the same physical or chemical quantities are more preferred in certain countries while some other alternative units are more used in other parts of the world. Some units are basic units of a scientific term and are used for smaller calculations on a limited scale. These units are denoted by specific symbols. Whereas other alternative units are used for the same quantities instead of their basic counterparts if larger scale calculation is required.

For example, if you are a manufacturer of thermometers and you are curating a scientific manual for using these thermometers for laymen. You have to understand temperature conversion and calculate temperatures easily and speedily. You may have to mention units that are more prevalent in your target country of sales. for instance, Fahrenheit is commonly used in the U.S.

Similarly, if you are an engineer submitting your final year project report about a self-manufactured microwave oven, you may need to review your scientific study paper more than once to have all the calculations correct. Your report may need to discuss the temperature values of your oven's thermostat system and available units for pre-heating or cooking mechanisms. You may require quick conversions and calculations to get the correct equational values and relational figures.

In this regard, online temperature converters tools work best as a handy solution. These temperature converters are programmed by the site developers. They either provide a link to an efficient temperature conversion calculator or these temperature converters embedded in the site itself. Either way, the need for these handy online tools cannot be denied.

What is Fahrenheit?

Proposed by and named after a German Physicist, Daniel Gabriel Fahrenheit, the Fahrenheit scale is a standard temperature scale used for measuring temperature in most countries including the U.S. the unit of Fahrenheit is a degree Fahrenheit denoted by °F.

According to the older accounts in the papers, the statements suggest his definition of the freezing point of water, ice, salt, and brine mixture to be set at 0°F. This was the initial point of his defined scale for temperature. The other upper point was his perception of human body temperature from 90°F to 96°F. The middle point of the scale was set to 32°F as per the temperature of ice water. Whereas the boiling of water was set at 212°F. These two points were the definition of this scale in the 20th century i.e. freezing and boiling point of water.

Fahrenheit Temperature Scale

According to Wikipedia, the Fahrenheit scale was the first temperature scale that got recognition as a standard temperature scale being used widely to date. The German Physicist, Fahrenheit made two breakthroughs in the field of thermometry at the start of the 18th century.

He developed an in-glass mercury thermometer and introduced the Fahrenheit scale. The use of this scale is now scarce in other countries or is mostly complimented by the Celcius scale. However, it is still the official temperature scale in the United States and most of its territories.

Fahrenheit and Celsius in Terms of Kelvin

As the degree difference between the two initial points on a Fahrenheit scale is 180°F from 32°F to 212°F, a degree Fahrenheit would be 1/180 of the gap between freezing and boiling points of pure water. The Fahrenheit and Celsius scales have an intersecting point at -40° so that equates to:

-40°F = -40°C

As both Fahrenheit and Celsius scales are expressed in terms of Kelvin now, 1°F corresponds to an interval of 5/9 °C and of 5/9 K. This means Fahrenheit is 1.8 times smaller than Celsius.

The Fahrenheit scale is used today in the U.S. for major applications such as weather forecasting, the food industry, and culinary sciences.

What is Celsius?

Until 1742, Celsius was called Centigrade then it was renamed after the Swedish Astronomer, Anders Celsius who was the inventor of another similar scale. It was initially named Centigrade in 1942 due to the 100 degrees gradient on the scale. In Latin, centum means "hundred" and gradus means "steps".

The unit of Celsius is the degree symbol (°) followed by a capital C. The value of temperature in degrees centigrade can be written before the symbol °C to denote temperatures in Celsius.

At 1 atmospheric pressure, the freezing point of water on the Celsius scale is set to be at 0°C and the boiling point is set to be at 100°C. The values were reversed before the year 1743 until it was reset by French Physicist Jean-Pierre Christin. The Celsius scale was defined as absolute zero until 2019. An absolute zero is the lowest point on a thermodynamic temperature scale. Afterward, Celsius was redefined with the Kelvin scale as the lowest temperature i.e. 0K is the same as -273.15°C.

Celsius Scale: The Most Widely Used Temperature Scale

Since the 19th century, the scientific community across the globe has standardized Celsius as the most commonly used temperature scale. Temperature values are often referred to as simply degrees or more specifically °C. Due to the possible confusion between angular measurement and temperature, the scientific community formally adopted the word Celsius for temperature contexts.

Since 1985, BBC has formally introduced Celsius as the standard unit of reporting temperature values in their weather forecasts. However, in English-speaking regions, in more informal contexts, the term centigrade is still very common.

From a science and engineering perspective, the magnitude of Kelvin is equal to that of Celsius thus the application of both is found to be in correlation with each other mostly. The practice of using °C and K alongside each other is widely common in the scientific field.

What is Kelvin?

Using absolute zero as its null point, equal in size to Celsius, the Kelvin scale is an absolute thermodynamic temperature scale. Kelvin is the unit of temperature denoted by K.  It is an SI (international system of units) basic unit of temperature named after an engineer and physicist of Glasgow University, William Thomson. He is known for his work in determining the correct value of 0K as -273.15 °C or -459.67°F. For his notable work in the field of thermodynamics, he received the noble title of Baron Kelvin in Ireland.

The title Kelvin denotes the river that flows near his research laboratory at Glasgow University where he remained until his retirement in 1899. He refused to leave Glasgow despite being offered several elevated positions worldwide. The idea of an absolute zero Kelvin scale was introduced in 1848 due to his dissatisfaction with a gas-powered thermometer that only provided an operational sense of temperature.

Kelvin as an Absolute Zero Temperature Scale

Kelvin worked hard to propose a scale where the temperature could be calculated irrespective of the physical properties of substances. Thus it was developed by setting the starting point of the Celsius scale that was set at the melting point of water to an absolute zero. It was speculated and later proved that there comes a point when no further heat can be transferred and that is what absolute zero is. Now the temperature in Celsius can be expressed in terms of kelvin with the subtraction of 273.15.

The Kelvin scale is mostly used in scientific fields where Kelvin is the primary unit of temperature for engineers and scientists. Apart from physical sciences, Celsius is more commonly used. Almost a century apart from its introduction to the scientific community, Kelvin is never referred to as degrees Kelvin unlike degrees Celsius or degrees Fahrenheit. Instead, it is mostly written as "x kelvins" i.e. a non-capitalized form unless referred to as the abbreviation. 1 kelvin is known to be an uncommon occurrence in this universe. Interestingly, temperatures colder than 1 K may have been produced in the laboratories but is not a naturally-occurring phenomenon. At 1 K temperature and 1 atm (atmospheric pressure), most of the substances are found in solid states such as Nitrogen, Hydrogen, and even Neon.

Until 1967, the kelvin was preceded by degrees or degrees absolute to denote temperatures on the Kelvin scale. However, to avoid confusion with the Rankine scale, it was later simply adopted as Kelvin or K as a short form. The removal of degrees refers to the fact that instead of being relative to an approximate point like Celsius and Fahrenheit, it is an algebraic unit and can be manipulated algebraically.

What is a Temperature Conversion Calculator?

You may have come across our online temperature converter and you may be wondering what it is used for. JFT’s online temperature conversion tools are simplified calculating tools to let you convert your temperature values from one scale to another. It saves you the trouble of going through an entire formula computation involving physical detail and background scientific knowledge. You just have to select your desired temperature scale and enter your available value and click "convert" and you are good to go.

As we have discussed earlier, temperatures are often expressed on different scales worldwide. Sometimes, people from different walks of life visit these sites that have a temperature conversion tool to convert their values to the scale of their preference. You can be a student or a scientist or an everyday baking mom, a pro culinary chef, or a lab assistant. You will encounter the need for a temperature converter once in a while.

Online calculators available on different websites should be used with care though, sometimes the values added should be cross-checked for accuracy. However, check out our trusted temperature conversion calculators that can cater to your requirements properly.

Temperature converter calculators have made daily computation tasks far easier for people. Many of us may not be interested or informed enough to understand the technicalities of temperature equations and standard formulas. To make things simpler, developers have programmed temperature conversion calculators and embedded computational tools within a website to let you convert your temperature value with fast speed and accuracy.

They have already encoded the working formula for conversion at the back end and you don't have to go through those details.

You can just enter your figures and get a converted value as a result. The conversion tools were introduced in the field of computer programming as an advanced idea of using computers as calculators. A simple desktop calculator won't suffice for complex scientific calculations and conversions, thus conversion tools were developed for easy computation. Now, a temperature converter tool, for instance, has made life easier for industry people. The available temperature converters on our site are in standard temperature scales including Celsius, Fahrenheit, Kelvin, and Rankine.

How to Use Our Temperature Conversion Calculators?

Featuring 4 main scales of temperature, most online temperature converters are easy-to-use requiring little background knowledge about scientific formulas. Our temperature converter also facilitates these 4 main scales for conversion.

The Rankine scale is not very common as compared to the other three scales that we have discussed above. Some of the basic information about the Rankine scale is separately given below to let you understand it before you make your conversions.

Rankine Scale

The Rankine scale was proposed by the Glasgow University engineer Macqourn Rankine and was named after him in 1859. Similar to another Glasgow University engineer and physicist, William Thomson who was the developer of the kelvin scale in 1848, Rankine also used absolute zero as the starting point of his scale. The only difference is that 1 Rankine degree or 1°R or Ra is equal to 1°F instead of 1°C as is the case with kelvin. Upon conversion of kelvin to °R, 0 K = 0 °R whereas 1 °R = 5/9 K or 1 K = 1.8 °R.

Rankine Scale application is mostly in engineering communities where Fahrenheit is the metric for most heat or temperature-related computations. Some scientific authors use just Rankine regarding SI unit kelvin omitting degrees Rankine when mentioning temperature in Rankine.

To let you understand how our temperature conversion calculator works for different scales of temperature, we have simplified the formulas for conversion by discussing each combination separately in the sections below.

The details are just for your background understanding. However, you can easily enter one temperature value in a field for let's say degrees Celsius and press the “CONVERT” button to get the values in other targeted temperature scales.  For instance, consider the snapshot of the Fahrenheit to Celsius scale conversion below:

In the image above, the our online temperature converter tool is shown with fields for Fahrenheit value to be converted to Celsius. Buttons show the facility to "convert" the entered value or "reset" the previous calculations.

Another button titled "swap" facilitates switching between the scales by reciprocating the current chosen combination for conversion.

The box below shows the calculating formula being applied by the conversion tool to let you make sense of the automatic scientific conversions being calculated within a blink of an eye.

Celsius to Fahrenheit Conversion

Based on the boiling and freezing points of water Fahrenheit is mostly used in the United States. If you have data in the American context, it would have temperature values in degrees Fahrenheit. You will have to convert it to the Celsius scale for a more inclusive approach or to generalize your content for a wider audience.

Celsius is more common worldwide and you will require a standard formula to convert your temperature value from degrees Fahrenheit to degrees Celsius. However, for fast conversion and from a layman's perspective that will surely prove to be a difficult and tedious task. This is where an online temperature conversion calculator may come in handy.

To let you understand the workings of this conversion let us consider the following equation:

°C = (°F-32)×5/9

In the decimal form, the fraction 5/9's value is 0.555.

For instance, you have measured your body temperature with a Fahrenheit scales thermometer and the result is 98.6°F.

To convert this value into Celsius, follow the formula above:

°C = (°F-32)×5/9

°C = (98.6-32)×5/9

°C = (66.6)×0.555

°C = 37 (Answer)

So the body temperature of 98.6°F equates to 37°C which is the normal body temperature of a human being.

You can easily convert from degrees Celsius to degrees Fahrenheit using our online tool here.

Fahrenheit to Celsius Conversion

To calculate temperature values from degrees Fahrenheit to degrees Celsius, the formula should be reversed.

°F = (°C×9/5)+32

For example, you want to have to preheat your American oven and you know the preheating should be done at 180°C. How to know the corresponding value in Fahrenheit? Just apply the formula above for conversion.  

°F = (°C*9/5)+32

°F = (180*1.8)+32

°F = (324)+32

°F = 356°F

So the preheating temperature in an American oven having a Fahrenheit scale should be set at approximately 356°F corresponding to 180°C.

You can use our online temperature conversion calculator to convert your temperature value from degrees Fahrenheit to degrees Celsius here.

Kelvin to Celsius Conversion

To calculate kelvin to degrees Celsius, the following formula is used:

°C = K - 273.15

It is the simplest of all temperature conversions. Just take your temperature value in Kelvin and minus 273.15 from it to get your value in degrees Celsius. For example, convert 300 K temperature to °C.

By applying the formula we will get:

°C = K - 273.15

°C = 300 - 273.15

°C = 26.85 rounded to 27°C

So upon converting 300 K to degrees Celsius we will get approx 27°C of temperature value. For ease of calculation, you can use our online kelvin to Celsius temperature converter.

Celsius to Kelvin Conversion

To convert Celsius into Kelvin, just reciprocate the above formula by adding the 273.15 instead of subtracting it. The formula will read as:

K = °C+273.15

For example, convert the freezing point of water that is 0°C into kelvins. By applying the formula we will get:

K = °C+273.15

K = 0°C+273.15

K = 273.15 kelvins

So upon converting 0° C (at which the water starts freezing) to kelvin, we will get approx 273 kelvin temperature value. For fast Celsius to kelvin conversion, you can use our temperature conversion calculator.

Kelvin to Fahrenheit Conversion

To convert temperature values from kelvin to Fahrenheit, the following working formula is programmed in the temperature conversion online tools:

°F = 9/5 (K - 273.15) + 32

To apply the formula, consider the BODMAS rule and solve the bracket first. Take a kelvin value and subtract 273.15 from it first, then multiply it by 1.8 or 5/9. Whatever the result is, just add 32 to it. You will get your value in degrees Fahrenheit.

For example, you have to convert 400 kelvins to degrees Fahrenheit.

°F = 9/5 (K - 273.15) + 32

°F = 1.8 (400 - 273.15) + 32

°F = 1.8×(126.85) + 32

°F = 228.33 + 32

°F = 260.33 °F

So the value of 400 kelvin is converted to degrees Fahrenheit as 260.33 °F. For easier, automatic calculation just uses our online temperature conversion tool for kelvin to Fahrenheit scale conversion.

Fahrenheit to Kelvin Conversion

To convert the Fahrenheit scale temperature value to kelvin, you can apply the following formula for manual conversion:

K = (°F - 32) × 5/9 + 273.15

For example, upon converting the body temperature of 98.6 degrees Fahrenheit to kelvin you will get the following value of kelvin.

K = (°F - 32) × 5/9 + 273.15

K = (98.6 - 32) ÷ 1.8 + 273.15

K = 66.6 ÷ 1.8 + 273.15

K = 37 + 273.15

K = 310.15 kelvins

So after putting the value in degrees Fahrenheit in the equation, first follow the BODMAS law and subtract 32 from this value. Then after the multiplication is changed to division and the denominator is reciprocated, the subtracted value will be divided by 1.8 or 9/5. Then 273.15 will be added to the result to get the correct converted value in kelvin.

For quick, automatic conversion try our temperature conversion calculator for Fahrenheit to kelvin conversion. 

How Our Tool Can Work for You?

Our online temperature converter can help you run fast calculations and temperature scale conversions easily and efficiently. The quick access to our tool will let you handle a multitude of conversions at a single time and perform a faster job as compared to manual, cumbersome conversions.

It is not only time-saving but also a practical way of doing scientific calculations these days. No matter which field or subfield of science, math, or physics you belong to, you can find it useful for your day-to-day calculations and solving work equations.

Even if your area of study is different from science yet you are a passionate pastry chef, you would come in contact with temperature conversions very frequently. It may be during your sophisticated recipe measurements or meticulous baking sessions, quick access to an online temperature converter will save you a lot of trouble.

Our tool will help scientists, research students, engineers, kitchen assistants, and lab workers alike. Whether there is research analysis or statistical report for thermodynamics or a user manual data for a kitchen appliance company or it is a clinical diagnosis being made by a lab assistant. Everyone can benefit from it one way or the other. This tool can be a go-to source for carrying out automatic temperature conversion online through a smooth, single click.  


Science has no longer remained a hypothetical field of arbitrary values and abstract ideas. Today it has become a practical way of living. Implementing scientific formulas, however, requires knowledge and effort. Life is busier every day and people need quick solutions to everyday problems. Our online free temperature converter calculator is an attempt to contribute to the advanced, automated world of science and technology.

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