Power from Current and Resistance Calculator
Find the power dissipated in a resistor from the current through it and its resistance using P = I²R. Enter current and resistance to see power when…
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Find the power dissipated in a resistor from the current through it and its resistance using P = I²R. Enter current and resistance to see power when you calculate.
Worked example
Example calculated from the starting values. Enter your own values and press Calculate to get your result.
With the default inputs (current = 5 A, resistance = 20 ohms), the results are: power 500.0 W.
Quick reference: current vs result
Reference table based on the example values; it is not your calculation result.
| Current (A) | Power |
|---|---|
| 2.5 | 125.0 W |
| 5 | 500.0 W |
| 10 | 2,000.0 W |
| 25 | 12,500.0 W |
| 50 | 50,000.0 W |
| 100 | 200,000.0 W |
Frequently asked questions
What formula does this calculator use?
Power = i^2 × r. Variables: i = current in A, r = resistance in ohms.
What do I need to enter?
You need current (A), resistance (ohms). Results update as you type.
What is an example result?
With the default inputs (current = 5 A, resistance = 20 ohms), the results are: power 500.0 W.
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