How to convert volts to ohms

How to convert electrical voltage in volts (V) to electric resistance in ohms (Ω).

You can calculate ohms from volts and amps or watts, but you can't convert volts to ohms since volt and ohm units do not measure the same quantity.

Volts to ohms calculation with amps

According to ohm's law, the resistance R in ohms (Ω) is equal to the voltage V in volts (V) divided by the current I in amps (A):

R(Ω) = V(V) /I(A)

So ohms are equal to volts divided by amps:

ohms = volts / amps


Ω = V / A


Calculate the resistance in ohms of a resistor when the voltage is 5 volts and the current is 0.2 amps.

The resistance R is equal to 5 volts divided by 0.2 amps, which is equal to 25 ohms:

R = 5V / 0.2A = 25Ω

Volts to ohms calculation with watts

The power P is equal to the voltage V times the currentI:

P = V × I

The current I is equal to the voltage V divided by the resistance R (ohm's law):

I = V / R

So the power P is equal to

P = V × V / R = V 2 / R

So the resistance R in ohms (Ω) is equal to the square value of voltage V in volts (V) divided by the power P in watts (W):

R(Ω) = V 2(V) /P(W)

So ohms are equal to the square value of volts divided by watts:

ohms = volts2 / watts


Ω = V2 / W


Calculate the resistance in ohms of a resistor when the voltage is 5 volts and the power is 2 watts.

The resistance R is equal to square of 5 volts divided by 2 watts, which is equal to 12.5 ohms.

R = (5V)2 / 2W = 12.5Ω

How to convert ohms to volts »

What is Ohm's law?

Ohm's Law is a formula used to calculate the relationship between voltage, current and resistance in an electrical circuit.

To students of electronics, Ohm's Law (E = IR) is as fundamentally important as Einstein's Relativity equation (E = mc²) is to physicists.

E = I x R

When spelled out, it means voltage = current x resistance, or volts = amps x ohms, or V = A x Ω.

Named for German physicist Georg Ohm (1789-1854), Ohm's Law addresses the key quantities at work in circuits:

QuantityOhm's Law
Unit of measure
Role in circuitsIn case you're wondering:
VoltageEVolt (V)Pressure that triggers electron flowE = electromotive force (old-school term)
CurrentIAmpere, amp (A)Rate of electron flowI = intensity
ResistanceROhm (Ω)Flow inhibitorΩ = Greek letter omega

If two of these values are known, technicians can reconfigure Ohm's Law to calculate the third. Just modify the pyramid as follows:

If you know voltage (E) and current (I) and want to know resistance (R), X-out the R in the pyramid and calculate the remaining equation (see the first, or far left, pyramid above).

Note: Resistance cannot be measured in an operating circuit, so Ohm's Law is especially useful when it needs to be calculated. Rather than shutting off the circuit to measure resistance, a technician can determine R using the above variation of Ohm's Law.

Now, if you know voltage (E) and resistance (R) and want to know current (I), X-out the I and calculate the remaining two symbols (see the middle pyramid above).

And if you know current (I) and resistance (R) and want to know voltage (E), multiply the bottom halves of the pyramid (see the third, or far right, pyramid above).

Try a few sample calculations based on a simple series circuit, which includes just one source of voltage (battery) and resistance (light). Two values are known in each example. Use Ohm's Law to calculate the third.

Currently, we have around 5659 calculators, conversion tables and usefull online tools and software features for students, teaching and teachers, designers and simply for everyone.

You can find at this page financial calculators, mortgage calculators, calculators for loans, calculators for auto loan and lease calculators, interest calculators, payment calculators, retirement calculators, amortization calculators, investment calculators, inflation calculators, finance calculators, income tax calculators, compound interest calculators, salary calculator, interest rate calculator, sales tax calculator, fitness & health calculators, bmi calculator, calorie calculators, body fat calculator, bmr calculator, ideal weight calculator, pace calculator, pregnancy calculator, pregnancy conception calculator, due date calculator, math calculators, scientific calculator, fraction calculator, percentage calculators, random number generator, triangle calculator, standard deviation calculator, other calculators, age calculator, date calculator, time calculator, hours calculator, gpa calculator, grade calculator, concrete calculator, subnet calculator, password generator conversion calculator and many other tools and for text editing and formating, downloading videos from Facebok (we built one of the most famous Facebook video downloader online tools). We also provide you online downloanders for YouTube, Linkedin, Instagram, Twitter, Snapchat, TikTok and other social media sites (please note we does not host any videos on its servers. All videos that you download are downloaded from Facebook's, YouTube's, Linkedin's, Instagram's, Twitter's, Snapchat's, TikTok's CDNs. We also specialise on keyboard shortcuts, ALT codes for Mac, Windows and Linux and other usefull hints and tools (how to write emoji online etc.)

There are many very usefull online free tools and we would be happy if you share our page to others or send us any suggestions for other tools which will come on your mind. Also in case you find any of our tools that it does not work properly or need a better translation - please let us know. Our tools will make your life easier or simply help you to do your work or duties faster and in more effective way.

These below are the most commonly used by many users all over the world.

And we are still developing more. Our goal is to become the one-stop, go-to site for people who need to make quick calculations or who need to find quick answer for basic conversions.

Additionally, we believe the internet should be a source of free information. Therefore, all of our tools and services are completely free, with no registration required. We coded and developed each calculator individually and put each one through strict, comprehensive testing. However, please inform us if you notice even the slightest error – your input is extremely valuable to us. While most calculators on are designed to be universally applicable for worldwide usage, some are for specific countries only.

Page Id: 1420

This website uses cookies to improve your experience, analyze traffic and display ads. Learn more