buncha/engineering/ohmslaw

Ohm's Law Calculator

What do you know?

Pick the two values you have. We'll compute the other two.

Voltage (V)

unit: V

Current (I)

unit: A

Solved

Resistance (R)

24 Ω

Power (P)

600 W

V (in)

120 V

I (in)

5 A

R (out)

24 Ω

P (out)

600 W

The four formulas

V = I × R
P = V × I
P = I² × R
P = V² ÷ R

DC math. These formulas assume direct current or purely resistive AC loads. For AC with motors, transformers, or other reactive loads, real power is P = V · I · cos(φ) where φ is the phase angle. Power factor 1.0 → these formulas are exact; power factor 0.85 (typical motor) → real power is 15% lower than V·I.

Read the guide

Ohm's Law in Practice — The Four Formulas That Run Every Circuit

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About Ohm's Law Calculator

Voltage, current, resistance, power — give us any two, we compute the other two. The wheel chart in calculator form.

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