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 Formula

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

R = V^2 / P


  • 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.

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