Wattage calculator

Electrical power = voltage × current.

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Voltage (V)

Current (A)

Answer

…

Electrical power = voltage × current.

More results

Precision and calculation record

Decimal places in numeric results and text downloads

Rounding changes displayed numbers, not the calculation. Text, fractions, matrices and CSV schedules keep their own formatting. Automatic keeps up to 12 significant digits, with money shown to cents where applicable.

Step-by-step calculation

Inputs are substituted below. Each line evaluates the next operation; intermediate values are displayed to 12 significant digits while the calculation uses full precision.

Saved scenario

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Formula and assumptions

Applies to DC or unity-power-factor AC using RMS quantities. For other AC loads, account for power factor separately.

Automatic precision shows numbers to 12 significant digits. Thousands separators such as 1,000 are accepted; use a dot for decimals.

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Updated 2026-09-26

Using Wattage calculator

Electrical power = voltage × current.

Applies to DC or unity-power-factor AC using RMS quantities. For other AC loads, account for power factor separately.

Next: Resistance calculator

A worked example

With voltage (v) = 12, current (a) = 3, the power (w) is 36.

Next: Capacitance to charge calculator

Before you use the result

Applies to DC or unity-power-factor AC using RMS quantities. For other AC loads, account for power factor separately.

Example results for voltage (v)

These examples use Current (A): 3. They are reference calculations, not recommended settings.

Voltage (V)	Power (W)
6	18
12	36
24	72

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