How to Calculate Watts to Amps
What is Watts to Amps?
A watts to amps converter calculates electrical current from power and voltage using Ohm's law. It is used for sizing circuit breakers, fuses, and cables for electrical installations.
Formula
A (DC) = W / V; A (AC) = W / (V × PF)
- W
- Power (W) — Electrical power in watts
- V
- Voltage (V) — Electrical potential difference in volts
- A
- Current (A) — Electrical current in amperes
- PF
- Power factor ((dimensionless)) — AC circuits only; typically 0.8–1.0
Step-by-Step Guide
- 1Amps = Watts ÷ Volts (DC circuits)
- 2Amps = Watts ÷ (Volts × Power Factor) (AC circuits)
- 3Standard voltages: 120V (US), 230V (UK/EU), 240V (AU)
- 4Power factor for resistive loads = 1.0
Worked Examples
Input
2400W appliance at 240V
Result
10 amps
Input
1200W microwave at 120V
Result
10 amps
Input
3000W oven at 240V
Result
12.5 amps
Frequently Asked Questions
What is the difference between watts and amps?
Watts measure power (energy per unit time). Amps measure current flow. Relationship: Watts = Volts × Amps.
Why do I need to know this?
For sizing circuit breakers, fuses, and electrical cables. An undersized wire can overheat; an incorrectly rated breaker won't protect the circuit.
What is power factor?
In AC circuits, power factor accounts for reactive loads (motors, inductors). A pure resistive load has PF = 1.0. Motors typically have PF = 0.8–0.95.
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