Watts to Amps Calculator

Find how much current an appliance draws from its wattage and supply voltage.

How the Math Works

The Watts to Amps Calculator uses the formula I = P ÷ V to determine electrical current (amps) from power (watts) and voltage (volts). This relationship stems from the fundamental equation for electrical power: P = V × I. By rearranging this formula to solve for current, we isolate I on one side, resulting in I = P/V. For example, a 1200W device operating at 120V draws 10 amps of current. The calculation assumes a direct proportionality between power and current, with voltage acting as the scaling factor.

Practical Applications

This calculation is essential for electrical system design and safety. Electricians use it to size circuits, select appropriate wire gauges, and ensure breakers can handle connected loads. Homeowners might apply it when installing appliances to verify their circuits won't overload. For instance, a 2400W space heater at 240V requires 10 amps, so it should be plugged into a dedicated 15A circuit. It also helps compare device efficiency—two devices with identical power ratings but different voltages will draw different currents.

Day-to-Day Use

Understanding current draw helps prevent common household electrical issues. By calculating amps, you can avoid overloading outlets or extension cords, reducing fire risks. It also informs decisions about energy usage, such as determining if a device can safely run continuously. For renters or homeowners, knowing these values aids in troubleshooting flickering lights, tripped breakers, or choosing compatible smart plugs. Additionally, it supports budgeting for energy costs, as higher current devices consume more electricity over time.

Worked example

1200 W at 120 V → 10 A.

FAQ