Enter the power and voltage into the calculator to determine the electrical resistance. This calculator can also evaluate any of the variables given the others are known.

Watts To Ohms Calculator

Enter any 2 values to calculate the missing variable

Watts To Ohms Formula

The following formula is used to calculate the electrical resistance in Ohms given power in Watts and voltage.

R = V^2 / P

Variables:

  • R is the electrical resistance (Ohms)
  • V is the voltage (Volts)
  • P is the power (Watts)

To calculate the electrical resistance, square the voltage and then divide by the power. This will give you the resistance in Ohms.

Watts to Ohms Conversion Table (V = 12 V DC)
Power (W) Resistance (Ω)
0.25576.000
0.5288.000
1144.000
272.000
348.000
528.800
7.519.200
1014.400
1212.000
159.600
207.200
255.760
304.800
403.600
502.880
602.400
751.920
1001.440
1500.960
2000.720
* Rounded to 3 decimals. Ohm's law: R = V² / P. Assumes constant voltage V = 12 V DC.

What is Watts To Ohms?

Watts and Ohms are units of measurement used in electrical systems. Watts measure the rate of energy conversion or transfer and is often used to quantify the output power of a system. Ohms, on the other hand, measure electrical resistance, indicating how much a device or material resists the flow of electric current. The relationship between these two units is defined by Ohm's Law and the Power Law in electrical engineering, which states that power (in watts) equals voltage squared divided by resistance (in ohms). Therefore, "Watts to Ohms" typically refers to the process of calculating electrical resistance given power and voltage.

How to Calculate Watts To Ohms?

The following steps outline how to calculate the Watts To Ohms using the formula: R = V^2 / P.


  1. First, determine the voltage (V) in Volts.
  2. Next, determine the power (P) in Watts.
  3. Next, use the formula R = V^2 / P to calculate the electrical resistance (R) in Ohms.
  4. Finally, calculate the Watts To Ohms.
  5. After inserting the variables and calculating the result, check your answer with the calculator above.

Example Problem : 

Use the following variables as an example problem to test your knowledge.

voltage (V) = 12 Volts

power (P) = 36 Watts