Convert Watts To Amps Calculator (What Is My Amp Draw?)

featured image convert watts to amps

The simple answer for how you convert watts to amps is to divide watts by volts to get amps.

Amps = Watts ÷ Volts

If you have 1000-watts and 120-volts, then amps is equal to 8.33.

In the world of home inspections, the most common reason to convert watts to amps is to determine the size of circuit breaker (and wire gauge) that is suitable for a home appliance.

If you hook up a water heater that is rated at 4000-watts and use a 15-amp breaker — it is going to overheat or constantly trip.

Watts To Amps Calculator



The Ohms Triangle

An easy way to look at converting watts to amps (or amps to watts etc.) is through a triangle.

You take one value (amps, volts, or watts) and if you divide it by the other value either above it or below it — it will convert it to the value on the side. The watts should always be on the top of the triangle as you can see from below.

the ohms triangle of converting watts to amps

Clothes Dryer 6500-Watts (Example 1)

Let’s say you have an electric clothes dryer that is rated at 6500-watts and it uses 240-volts.

So… 6500-watts ÷ 240-volts = 27.08-amps.

And if you round up from 27.08-amps then you would need a breaker of at least 30-amps.

The wiring (gauge) should also be able to handle it. A 30-amp breaker would need an 10-awg copper wire.

Read Also: What Are The Best Bathroom Fan Timer Switches?

Microwave 1800-Watts (Example 2)

Imagine you want to install a new microwave that pulls 1800-watts. It will need to be on a individual or dedicated circuit and say it uses 120-volts.

So… 1800-watts ÷ 120-volts = 15-amps

So at minimum you would need a 15-amp breaker. The wire needs to be at least 14-gauge for copper.

The Concept of Watts, Amps, And Volts

water metaphor for amps, watts, and volts

The easiest way to think of amps, watts, and volts is to think of it as water.

Imagine you are powering a water wheel with a hose. There are only two things that you can increase to make the wheel turn faster, the water pressure or the volume of water.

The water pressure is the voltage, and the volume of water (per second) is the amps. And when you multiply the pressure and the volume per second — you get the power (watts) of the water wheel or how fast it turns.

Wire Gauge Must Match Breaker

As stated earlier, if you plan on upgrading a circuit for an appliance, you can’t just swap out a breaker. The larger amp breaker needs to match the capacity of the wire.

In the U.S. and Canada, wire size is called A.W.G. or American wire gauge. The smaller the gauge, the larger the wire. The most common size for branch circuits, regular outlets and lights, is a 14 gauge wire coupled with 15-amp breakers.

Aluminum Wiring Is Only For Larger Amps

Most service conductors are copper and aluminum. Aluminum is usually reserved for higher amp circuits, and aluminum wiring that is used for 15-amp, 20-amp, and 30-amp breakers will go into my home inspection report as a possible defect.

But for 40-amp and above, aluminum single strand is totally fine.

Breaker SizeCopper WireAluminum WireCommon Uses
15-amp14-awg*12-awgOutlets/Lights, Fridge, Dishwasher
20-amp12-awg*10-awgKitchen GFCIs, Microwave, Fridge, Washer
30-amp10-awg*8-awgDryers, Generator
40-amp8-awg6-awgStove/range, Generator
50-amp8-awg6-awgStove/range, Generator
60-amp6-awg4-awgHigh Watt AC Units

*Aluminum for lower amp circuits is a possible defect

Read Also: What Are The Top Exhaust Fan Timer Switches?

Watts To Amps Conversion Table

Below is a simple conversion table for wattage to amps…

300-watts2.50-amps 120-volts
400-watts3.33-amps 120-volts
500-watts4.17-amps 120-volts
600-watts5.00-amps 120-volts
700-watts5.83-amps 120-volts
800-watts6.67-amps 120-volts
900-watts7.50-amps 120-volts
1000-watts8.33-amps 120-volts
1100-watts9.17-amps 120-volts
1200-watts10.00-amps 120-volts
1300-watts10.83-amps 120-volts
1400-watts11.67-amps 120-volts
1500-watts12.50-amps 120-volts
1600-watts13.33-amps 120-volts
1700-watts14.17-amps 120-volts
1800-watts15-amps 120-volts
1900-watts15.83-amps 120-volts
2000-watts16.67-amps 120-volts
2100-watts17.50-amps 120-volts
2200-watts18.33-amps 120-volts
2300-watts19.17-amps 120-volts
2400-watts20.00-amps 120-volts
2500-watts20.83-amps 120-volts
2600-watts21.68-amps 120-volts
2700-watts22.50-amps 120-volts
2800-watts23.33-amps 120-volts
2900-watts24.17-amps 120-volts
3000-watts25.00-amps 120-volts
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Arie Van Tuijl

Arie Van Tuijl

I am a licensed home inspector in two U.S. states and the founder of Home Inspector Secrets. After performing hundreds of inspections, and seeing thousands of house defects, I realized people would love to have an online resource dedicated to home maintenance. I write detailed home guides and product reviews sprinkled with inspection tips. You can read my bio here.

About Home Inspector Secrets

Home Inspector Secrets is an online resource for owners, buyers, and sellers to understand all aspects of home maintenance. We have detailed home guides, product reviews, inspection advice, and much more.

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Looking to learn more about home maintenance? Check out our other informative home product reviews and guides!