Amps to Watts

Convert electrical current in amps to power in watts using voltage and power factor. Free, instant, no signup.

Formula: Watts = amps × volts × power factor

How to use the Amps to Watts

  1. Enter your values. Fill in the fields with your numbers.
  2. Calculate. Press Calculate to run the amps to watts.
  3. Use the result. Copy the result or try a related tool next.

Why use our Amps to Watts

Instant results. Enter your figures and the amps to watts returns an answer in seconds.
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About the Amps to Watts

The Amps to Watts converter turns a current reading in amperes into electrical power in watts, but only once you tell it the voltage. Amps measure how much current flows; watts measure how much work that current actually does. The two are linked by the voltage pushing the current along, which is why this tool always asks for volts alongside amps. Drop in a 5 A reading at 120 V and you get 600 W; the same 5 A at 240 V gives 1,200 W. That dependence on voltage is the single most important thing to understand, and it is exactly what this converter handles for you.

Reach for this tool whenever you need to know the real load a device places on a circuit. Electricians and DIYers use it to check whether appliances will overload a breaker: a 15 A breaker on a 120 V line tops out near 1,800 W, and a 20 A circuit at 120 V around 2,400 W. RV owners, van builders, and solar hobbyists use it to size inverters, wiring, and charge controllers from a battery's amp draw, since 12 V, 24 V, and 48 V systems all behave differently. It is also handy for reading equipment nameplates where current is listed but wattage is not.

Under the hood, the converter uses the standard power equation. For DC and for purely resistive AC loads like heaters or incandescent bulbs, watts = amps x volts. For other AC loads it multiplies in the power factor (watts = amps x volts x power factor), and for three-phase supplies it adds a factor of the square root of 3 for line-to-line voltage. Power factor reflects how much current does useful work: resistive loads sit at 1.0, while motors and pumps often run between 0.7 and 0.9. Choosing the correct circuit type and power factor is what keeps the result honest.

Results are only as accurate as the figures you enter, so use the actual measured or nameplate voltage and a realistic power factor rather than a guess; an assumed PF of 1.0 on a motor load will overstate the watts. Treat the output as a planning and sizing estimate, not a substitute for a clamp meter or a licensed electrician on safety-critical work. The whole calculation runs in your browser using simple arithmetic, so your voltage, current, and power numbers never leave your device or get stored on a server.

Frequently asked questions

Why does this converter need the voltage and not just the amps?

Watts measure power, which depends on both current and the voltage driving it, so amps alone cannot give you watts. The same current produces very different power at 12 V, 120 V, or 240 V, which is why voltage is a required input.

What is the formula to convert amps to watts?

For DC and resistive AC loads it is watts = amps x volts. For AC loads with a power factor, watts = amps x volts x power factor, and for three-phase line-to-line supplies you multiply by an additional square root of 3.

What power factor should I use?

Use 1.0 for purely resistive loads such as electric heaters, toasters, and incandescent bulbs. Motors, pumps, and many electronics run lower, typically 0.7 to 0.9, so check the device nameplate or use about 0.8 for a general motor estimate.

How many watts is 15 amps?

It depends on voltage. At 120 V, 15 A is 1,800 W; at 240 V the same 15 A is 3,600 W. This is why a 15 A breaker on a standard 120 V circuit is usually rated for roughly 1,800 W of load.

Should I use DC or single-phase for a car or solar battery?

Batteries supply direct current, so choose DC and enter the system voltage, such as 12 V for most cars or 24 V and 48 V for many solar setups. The converter then uses the simple watts = amps x volts formula with no power factor.

From our blog

Meters to Feet: The Exact Factor, Quick Mental Math, and Where People Get It Wrong

By the Super Simple Digital Tools Team · Updated June 2026

Most of the world measures length in metres, but feet refuse to disappear, especially in US real estate, aviation altitudes, construction, and everyday talk about height. That mismatch is why a meters-to-feet conversion is one of the most repeated calculations online. The good news is that, unlike many unit swaps, this one rests on a clean, legally defined number rather than a messy approximation, so once you know the factor you can convert confidently every time.

The single fact to remember is that one foot equals exactly 0.3048 metres, agreed internationally in 1959. Flip that relationship and one metre becomes 1 divided by 0.3048, which is 3.280839895 feet. So to go from metres to feet you always multiply, and to go from feet back to metres you divide by the same number (or multiply by 0.3048). Keeping the direction straight, multiply for metres-to-feet, divide for feet-to-metres, prevents the most common beginner error.

For everyday estimates you rarely need nine decimal places. Multiplying by 3.28 is accurate to within a centimetre for typical room and height values, and rounding to 3.3 is fine for a rough sense of scale: a 3 m ceiling is roughly 9.9 ft, close enough to picture. The catch is that small rounding errors grow with distance. Over a 100 m running track the difference between using 3.28 and the full factor is a few centimetres, but over kilometres it becomes metres, so use the precise factor whenever the length is large or the stakes are high.

Feet on their own can feel abstract, which is why feet-and-inches is often the more useful output. After converting to feet, the whole number is your feet and the leftover decimal, multiplied by twelve, gives inches. Take 1.75 m: it is 5.7415 ft, and 0.7415 x 12 is about 8.9 inches, so roughly 5 ft 9 in, the way a person's height is normally spoken. This two-step split is exactly what trips people up, because they forget that the decimal part is a fraction of a foot, not a fraction of an inch.

Where does precision actually matter? For hanging curtains, sizing furniture, or comparing apartment listings, two decimal places of feet is plenty. For surveying, engineering drawings, or legal property descriptions, carry more decimals and, where possible, state the exact 0.3048 m factor so nothing is lost in rounding. Note too that the old US survey foot, very slightly different from the international foot, was officially retired for new work at the start of 2023, so today you should treat one foot as exactly 0.3048 m in essentially all applications.

  • Multiply by 3.28 for quick everyday conversions, but switch to the full 3.280839895 factor for long distances or technical work where rounding error compounds.
  • To get inches, multiply only the decimal part of your feet result by 12, not the whole number, then read it as feet plus inches.
  • Remember the direction: multiply metres by 3.28 to get feet, and divide feet by 3.28 (or multiply by 0.3048) to go back.
  • For property comparisons, convert the metre dimensions first, then multiply length by width in feet, rather than converting a square-metre area with the linear 3.28 factor.

Read the full guide →

Tool by the Super Simple Digital Tools Team. Reviewed by our editorial team. Free to use, no signup required.

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