Skip to content
M2TOOLKIT

Popular tools

Menu

Ohm's Law Calculator

Know two of volts, amps, ohms and watts? Get the other two.

  • Free
  • No sign-up
  • Nothing is sent or stored
V
A

Result

Voltage · Current · Resistance · Power
12 V · 2 A · 6 Ω · 24 W
Voltage (V)
12 V
Current (I)
2 A
Resistance (R)
6 Ω
Power (P)
24 W
How it was calculated
  1. V = I × R
  2. P = V × I = I²R = V² ÷ R

The calculation happens instantly in your browser. The numbers you enter are not sent to our servers or saved.

How to use the Ohm's Law Calculator

  1. Choose which two values you know.
  2. Enter them.
  3. Read voltage, current, resistance and power.

What does this tool do?

Ohm's law says voltage equals current times resistance: V = IR. Combined with P = VI, any two of the four quantities determine the other two.

For example, a 12 V supply across a 6 Ω resistor drives 2 A and dissipates 24 W.

Why use it?

  • All six combinations of two inputs.
  • Power included.
  • Formula reference.

The formula

V = I × R
P = V × I = I²R = V² ÷ R

Privacy

The calculation happens instantly in your browser. The numbers you enter are not sent to our servers or saved. There's no account to create and nothing to install.

Last reviewed by the M2Toolkit team.

Other tools people use alongside the ohm's law calculator.