Created By : Vaibhavi Kumari

Reviewed By : Rajashekhar Valipishetty

Last Updated : May 15, 2023

One of the most useful tools for determining power, current, and resistance is our free Watt Calculator. Simply enter the information needed in the calculator's boxes, such as resistance and voltage, then press the compute button. Power and current are seen as quickly as possible in the output area.

Choose a Calculation:
Current (I):

Ohm's Law and Watt's Equation

The unit of power is Watt. When a current of one ampere passes through a conductor with an electrical potential difference of one volt, this is the rate of work.

1W = 1V x 1A

Watt Equation: A watt is defined as the product of volt and amp in an electrical circuit. P = V x I

Ohm's Law: According to Ohm's law, the voltage across a conductor is proportional to the current flowing through it. V = I x R

The terms volts, amps, ohms, and watts are all defined here and their formulae.

Power: The rate at which electrical energy is transferred per unit of time is called power. The watt is its measurement unit.

  • P = V x I
  • P = V²/R
  • P = I² x R


Voltage: The potential difference between two conductor points is known as voltage. The volt is its measurement unit.

  • V = I x R
  • V = P/I
  • V = √(P x R)


Current: The amount of electrons travelling through any location of a conductor per unit of time is called current. The measuring unit is amperes.

  • I = V/R
  • I = P/V
  • I = √(P/R)


Resistance: The resistance of a wire is its ability to resist the flow of electrons in the opposite direction. The ohm is its measurement unit.

  • R = V/I
  • R = V²/P
  • R = P/I²

Where, R = resistance, I = current, P = power, V = voltage.

How to Calculate Watts and Amps?

The steps to compute watts, amps, and ohms in a circuit are listed below. Check the power value by looking over all these rules and following them.

  • Step 1: Calculate the resistance and voltage.
  • Step 2: To calculate current, divide the voltage by resistance.
  • Step 3: To find the power value in Watt, multiply the voltage and current.

How to Use the Watt Calculator?

The following is the procedure how to use the watt calculator

  • Step 1: Enter the unknown values. For example, resistance and voltage and x are in the appropriate input fields.
  • Step 2: To receive the result, select "Calculate the Unknown" from the drop-down menu.
  • Step 3: In the output field, the power and current will be displayed.

For more concepts check out to get quick answers by using this free tool.

Watt Calculation Examples

Question 1: Find the current and resistance of a 160 Watt light bulb with 180 volts of electrical potential.


Given Voltage V = 180 V

Power P = 160 W

Current I = P/V

I = 160/180

= 0.88 A

Resistance R = V/I

R = 180/0.88

R = 204.54 Ω

Hence, the current and resistance are 0.88 A, 204.54 Ω.

FAQs on Watt Calculator

1. How do you calculate watts?

The number of watts is calculated by multiplying amps by volts. This formula is written as W=A x V on occasion.

2. How do I calculate current?

The ratio of the potential difference to the resistance is the current. It has the following representation: (I). I = V/R has to be the recent formula. The ampere is the SI unit of current.

3. What is the wattage of a microwave?

Microwaves typically range from 600 to 1,200 watts. Microwaves with a higher wattage tend to be larger and more expensive, thus this is a price and size concern that can have a significant impact on microwave cooking performance.

4. How can I find ohms and amps with the Watt Calculator?

Simply enter the known numbers, such as voltage and power, in the calculator fields and press the blue colour to calculate button to quickly see the resistance and current values in the output field.