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Electrical Calculators

Resistance from Power Calculator

Verified formula Updated Jun 2026 Private — runs on your device

Enter details
V
W
Verified formula Private

Resistance

529.0000

Current
0.4348

For general information only — not financial, tax, legal or medical advice. Verify before you rely on it.

How to use the Resistance from Power Calculator

The Resistance from Power Calculator works out your resistance, along with 1 related figure in an instant. Enter voltage and power and the result updates as you type — it is free, needs no sign-up, and runs entirely in your browser so your figures stay private.

  1. Enter the voltage.
  2. Enter the power.
  3. Read off your resistance, together with current — the calculator updates automatically, with no button to press.

Formula

The Resistance from Power Calculator uses the formula:

Resistance = Voltage ^ 2 ÷ Power

Worked example

For example, with voltage of 230 V and power of 100 W, the resistance is 529.0000.

Inputs used
Voltage 230 V
Power 100 W
Results
Resistance 529.0000
Current 0.4348

Results are estimates for educational use, not professional advice.

Frequently asked questions

Use R = V² ÷ P. A 100 W device on 230 V has a resistance of about 529 ohms.

Divide power by voltage: I = P ÷ V. The calculator shows this too.

Yes. The simple relationship holds for resistive loads with a power factor of 1.

Combining P = VI with V = IR gives R = V² ÷ P, linking power, voltage and resistance.

The Resistance from Power Calculator uses the formula: Resistance = Voltage ^ 2 ÷ Power. For example, with voltage of 230 V and power of 100 W, the resistance is 529.0000.

Enter the voltage. Enter the power. Read off your resistance, together with current — the calculator updates automatically, with no button to press.

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