Watts to Amps Calculator

Use this calculator to convert watts to amps and amps to watts. Options are available for both alternating current (AC) and direct current (DC). Conversion charts, are available further down the page.

How do you convert watts to amps?

The formula for converting watts to amps (at a fixed voltage) is:

• 1500 watts / 120 volts = 12.5 amps
• 3000 watts / 120 volts = 25 amps

How do you convert amps to watts?

The formula for converting amps to watts (at a fixed voltage) is:

• 15 amps × 120 volts = 1800 watts
• 20 amps × 120 volts = 2400 watts

• Watts & amps at 120V (AC)
• Watts & amps at 12V (DC)

Understanding watts, amps and volts

If trying to convert amps, watts and volts manually has got you feeling wired, then settle down and plug in to our handy guide to discover what’s watt. You’re sure to have a lightbulb moment in no time!

Amps

Amps are amperes, a unit which measures electrical current. It can be helpful to imagine electrical current as water in a hose. In this analogy, the quantity (volume) of water would be the amps.

Volts

Volts are a unit to measure force. They measure the force required to make the electrical current (amps) flow. In the hose analogy, the volts would be the water pressure. North American homes typically use 120V for their electrical supply, whilst 230V is common across many other countries.

Watts

Watts represent the amount of energy produced by the amps and volts working together. Multiplying amps (water volume) by volts (water pressure) gives you the wattage (the resulting power or energy). A water wheel would turn faster and longer, generating more energy if it uses increased water volume and higher water pressure; the same applies to the wattage if amps and volts are increased.

AC/DC

DC stands for direct current, when the current flows in one single direction. A flashlight with a battery uses a direct current.

AC stands for alternating current, when the current periodically changes direction. In Northern America and Western Japan, this usually happens 60 times per second, or 60Hz / hertz. In Europe, the UK, East Japan and most of Australia, South America, Africa and Asia, the current changes direction 50 times per second, which is 50Hz. Power supplied to homes and businesses uses AC supply.

How to convert amps to watts manually

The Watt’s Law formula is all that’s needed for these unit conversions. The wattage (power produced / P) is calculated by multiplying the amps (current / I) by the voltage (force / E):

Power (P) = Current (I) x Voltage (E)

So…

watts = amps × volts

How to convert watts to amps

To find the amps, you work backwards with Watt’s Law and divide the wattage by the volts:

Current (I) = Power (P) ÷ Voltage (E)

So…

amps = watts ÷ volts

And…

If you’re working with larger units, you need to remember that 1 kilowatt is equal to 1000 watts. The formula for Watt’s law stays the same, just as long as you express the wattage in watts (your sum will go wrong if you use ‘5W’ to mean ‘5KW’; you need to use 5000W instead).

It’s simple, really, but if you’re feeling short-circuited after all those numbers, just use our watts and amps conversion calculator above.

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