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Ohm’s law calculator

Calculate current and power from a DC voltage and an ideal ohmic resistance.

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01

Your inputs

The starting values are an example.

Decimals: 12.5 · Thousands: 1,234.56. Follow the field instructions for lists.

02

Your result

Enter your values and select Calculate.

Your calculation will appear here.

Your result will include the relevant values and units.

Understand the calculation

Formula and example

How it is calculated

I = U/R; P = U × I = U²/R

Worked example

12 V across 100 Ω gives 0.12 A and 1.44 W.

Things to check

  • The calculation assumes a constant resistance. Component heating can change it.
  • This is a physical calculation model. It does not select component ratings or permissible loads.