Ohm's Law: Voltage & Power

I know voltage and power. Solve for current and resistance.

I = P / V, R = V² / P

Common Voltage & Power Calculations

5V, 1AR=5Ω, P=5W9V, 2AR=4.5Ω, P=18W12V, 3AR=4Ω, P=36W24V, 5AR=4.8Ω, P=120W48V, 10AR=4.8Ω, P=480W120V, 5AR=24Ω, P=600W120V, 10AR=12Ω, P=1,200W120V, 20AR=6Ω, P=2,400W240V, 10AR=24Ω, P=2,400W240V, 30AR=8Ω, P=7,200W480V, 20AR=24Ω, P=9,600W480V, 50AR=9.6Ω, P=24,000W

Other Input Pairs

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person Written by Sean Day verified Reviewed by WireResult update Last updated Apr 11, 2026