Ohm’s law calculator: voltage, current, resistance, power
Fill in only two boxes and leave the others empty: Ohm’s law gives the missing values.
Result
2 ACurrent I
- Power P
- 24 W
Inputs
- Voltage V
- 12
- Current I
- 0
- Resistance R
- 6
- Power P
- 0
How it is calculated
Ohm’s law: V = R × I.
Result
Current I
- Power P
- 24 W
How it is calculated
- Ohm’s law: V = R × I.
- Power: P = V × I = R × I² = V² ÷ R.
- With two known values, solve for the other two.
Example
12 V across 6 Ω: I = 12 ÷ 6 = 2 A and P = 12 × 2 = 24 W.
Good to know
- Valid for a simple resistor in DC or purely resistive AC.
- Leave unknown values empty (or 0); negative values are not accepted.
- Mains voltage is dangerous: do not take measurements without training.
Frequently asked questions
What is this tool used for?
Fill in only two boxes and leave the others empty: Ohm’s law gives the missing values.
How is the result calculated?
Ohm’s law: V = R × I.
What should I check before using the result?
Valid for a simple resistor in DC or purely resistive AC.