Amps to Ohms Calculator
Calculate resistance in ohms from current and voltage (R = V / I) or current and power (R = P / I²).
Enter Values
Calculate using
Enter current and voltage or power, then click Calculate.
Resistance
0
Ω
Formula Applied
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Summary
Calculate resistance in ohms from current and voltage (R = V / I) or current and power (R = P / I²).
How it works
- Enter the current in amperes (A).
- Enter either the voltage in volts (V) or the power in watts (W).
- Read the resistance in ohms — the tool uses R = V / I, or R = P / I² when you supply power.
Use cases
- Determine the resistance of a circuit element given its supply voltage and operating current.
- Size a resistor to limit current in an LED or other low-power component.
- Verify that a heating element's resistance matches its rated wattage and current draw.
- Troubleshoot electrical faults by comparing calculated resistance to measured values.
Frequently Asked Questions
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Last updated: 2026-05-23 ·
Reviewed by Nham Vu