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Amps to Watts Calculator

Convert amps and volts into watts. Enter the voltage and current to see power in watts, kilowatts and the energy used over one hour.

Power
2,300 W
Kilowatts2.3 kW
Energy (1 hour)2.3 kWh
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How it works

Electrical power (watts) equals voltage (volts) multiplied by current (amps). Kilowatts are watts divided by 1,000.

Watts = Volts × Amps

Worked examples

  • A 230 V appliance drawing 10 A

    2,300 watts, or 2.3 kW: watts = amps x volts, and 230 V is the Tanzanian domestic supply.

  • The same current on a 240 V supply

    2,400 watts - 100 W more than at 230 V, which is why the voltage has to be the one actually supplied, not an assumed one.

  • Kilowatts are a rate, kilowatt-hours are an amount

    A 2,300 W appliance running for one hour uses 2.3 kWh, but running it for eight hours uses 18.4 kWh at the same 2,300 W. The wattage does not change with time; only the energy consumed does, which is why a bill is charged in kilowatt-hours rather than kilowatts.

What this assumes, and where it does not apply

What it assumes

  • Applies watts = amps x volts to the figures you enter.
  • 230 V is the Tanzanian domestic supply, so that is the figure to use for a household appliance here.
  • The appliance is assumed to draw the same current throughout, so a device that cycles on and off, such as a fridge or an iron, averages less than the figure here.

Where the result does not apply

  • Alternating-current loads with a poor power factor draw more current than the wattage suggests; this is a direct-current relationship.
  • Does not apply to three-phase equipment, where the voltage and the configuration both change the relationship.
  • It does not apply to a device with a motor or a compressor whose starting current is several times its running current, so a fuse sized on the running figure alone can still trip.

Frequently asked questions

How do I convert amps to watts?

Multiply amps by volts: watts = amps × volts.

What is a kilowatt-hour?

A kWh is the energy used by a 1,000-watt device running for one hour.

What voltage should I use?

Household mains is 230 V in Tanzania and most of the world, and 120 V in North America.

Why is my appliance labelled in watts but my bill in kilowatt-hours?

A watt is a rate at which energy is used and a kilowatt-hour is an amount of energy. A 1,000 W appliance left on for one hour uses 1 kWh, and the same appliance for two hours uses 2 kWh.

Sources: NIST Special Publication 811 — Guide for the Use of the International System of Units (SI)

Maintained by David M at Delta Tech Solutions · Figures last checked 10 October 2026 · Next check due 10 April 2027

Read the guide: What a Unit of Electricity Costs in Tanzania →

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