Knowing how many amps a device draws helps you avoid overloading a circuit or choosing the wrong breaker or extension cord.
How to Use This Calculator
Enter the device’s power rating in watts (found on its label) and the supply voltage (120V is standard for US household outlets), then click Calculate.
Formula
Amps = Watts ÷ Volts. This is a simplified version of Ohm’s Law used for basic AC power calculations at unity power factor.
For circuit and breaker sizing, always follow local electrical code and consult a licensed electrician — this calculator is for general estimation only.
Frequently Asked Questions
How many amps does a 1200W device draw at 120V?
1200W ÷ 120V = 10 amps.
Is this formula accurate for all appliances?
It’s accurate for purely resistive loads (heaters, incandescent bulbs). Motors and electronics may draw more due to power factor — check the nameplate rating when possible.
What voltage do US homes use?
Standard household outlets are 120V; larger appliances like dryers and ovens typically use 240V.