About

Electrical safety and circuit design rely on understanding the relationship between Power, Voltage, and Current. Electricians, hobbyists, and engineers use this calculation to determine if a wire gauge is sufficient or if a power supply can handle a specific load. Overloading a circuit by drawing too much current (Amps) generates excess heat, leading to component failure or fire hazards.

This tool utilizes Ohm's Law to derive the current when power and voltage are known. Unlike fixed-voltage calculators, this interface permits custom voltage inputs, making it suitable for low-voltage DC microcontrollers, standard household AC mains, or high-voltage industrial machinery.

Formulas

The calculation derives from the fundamental power equation of Ohm's Law. For a resistive load, the relationship is linear:

I = PV

Where:

I = Current (Amperes)
P = Power (Watts)
V = Voltage (Volts)

Reference Data

Voltage Source	Power (W)	Current (A)	Application Context
5 V (USB)	10	2.0	Tablet Charging
12 V (Auto)	60	5.0	Car Headlight
110 V (US)	100	0.91	Old Incandescent Bulb
120 V (US)	1500	12.5	Space Heater
220 V (EU)	2000	9.09	Electric Kettle
240 V (UK)	3000	12.5	Heavy Duty Tool
400 V (Ind)	10000	25.0	Industrial Motor
3.3 V (Logic)	0.5	0.15	Microcontroller Pin

Frequently Asked Questions

Mathematically, division by zero is undefined. In electrical terms, having zero voltage implies no potential difference exists to push the electrons, meaning no current can flow regardless of the theoretical power. The tool will flag this as an invalid state rather than displaying an infinite result.

This formula applies directly to DC circuits and AC circuits with resistive loads (like heaters or incandescent bulbs). For AC circuits with motors or transformers (inductive loads), a Power Factor correction is technically required, though this general tool provides a baseline estimate.

Wires are rated by their thickness (gauge) to carry a maximum amount of current. Exceeding this limit causes the wire to heat up. Converting Watts to Amps allows you to select the correct fuse size and wire gauge for safety.

Yes. Precise electronics often operate at voltages like 3.3V or 1.8V. The tool supports decimal inputs for both power and voltage fields.