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Amps to watts calculator

Enter the current in amps and see the power in watts. Choose DC, single-phase AC or three-phase; if you leave the voltage empty we use 230 V, or 400 V for three-phase.

What do you want to know?
Type of current

In watts; 2.3 kW works too.

In amps.

In volts. Empty = 230 V (UK, Europe), or 400 V for three-phase. In the US it is 120 V.

Empty = 1 (heaters, lamps). Motors and power supplies: 0.8 to 0.95.

Fill in the fields; the answer appears here straight away.

How it works

  1. Enter the values

    Type the numbers or the formula. Decimals may use a point or a comma. No idea? Click Fill in an example.

  2. Instant answer

    The answer appears as you type, with the most important intermediate values.

  3. See the working

    Under "How it's worked out" you see the steps, handy for checking your own calculation.

How to convert amps to watts

Power is voltage times current:

  • DC: P = U × I
  • Single-phase AC: P = U × I × cos φ
  • Three-phase AC: P = √3 × U × I × cos φ, where U is the voltage between two phases (400 V)

A 16 A circuit on 230 V delivers 230 × 16 = 3680 W. On a 120 V supply the same 16 A is 1920 W: type 120 in the voltage field.

Amps and watts for a connection

| Breaker | Single phase, 230 V | Three phase, 400 V | |---|---|---| | 10 A | 2300 W | 6928 W | | 16 A | 3680 W | 11,085 W | | 25 A | 5750 W | 17,321 W | | 32 A | 7360 W | 22,170 W |

Values at cos φ = 1. This is why an electric car charges at about 3.7 kW from a single-phase 16 A supply, and at about 11 kW from a three-phase 16 A supply.

Working out the voltage

Choose Volt to find the voltage when you know the power and the current, for example for an adapter or a battery. For DC, such as a 12 V charger, choose DC: the power factor plays no part.

A word of caution

The result is the power that goes with this current. A circuit shouldn't simply be loaded to the full breaker rating all the time; leave changes to your installation to a qualified electrician.

Need the other direction? Use watts to amps. For batteries and power banks there is mAh to Wh.

Frequently asked questions

Is the amps to watts free?

Yes. The amps to watts is completely free, with no account, sign-up or usage limit.

How accurate is the result?

The tool calculates with your browser's number precision. For important calculations, always double-check what you entered.

Does it work on my phone?

Yes. The tool works in any modern browser on a phone, tablet or computer.