Ohm's Law Calculator (Residential)

V = IR. Pick which to solve for. Residential circuit framing.

Inputs

Result

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General calculation reads

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Scientific calculator (Casio fx-991EX)
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How to use this calculator

  • Pick which value to solve for.
  • Enter the two known values.

About this calculator

Ohm's law for residential / electrical-installation context. For a richer version with power formulas (P = IV = I²R = V²/R), see /calc/science/ohms-law-extended.

Frequently asked

Standard US voltages?+
120 V (most outlets/circuits). 240 V (large appliances: dryers, ranges, ACs).
How does this apply to home wiring?+
Each appliance has a current draw at its operating voltage. Use Ohm's law to verify circuit loading.
AC vs DC?+
For pure resistive loads, Ohm's law works for both. For motors and capacitive loads, impedance (Z) replaces R.
Why is this in construction not science?+
Both — different framings. Construction calculator focuses on residential wiring; science version is more theoretical.
How is this different from ohms-law-extended?+
Extended adds P = IV with all 4 wheel-formulas. This is the basic V = IR.

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Ohm's Law Calculator (Extended)
V = IR, P = IV = I²R = V²/R. Pick which two values you know and solve for the others.
Electrical Power Calculator
P = IV — compute power from voltage and current, or from voltage and resistance, or current and resistance.

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