Watts to Amps Calculator
Watts to Amps Calculator
Converting watts to amps is essential for sizing circuit breakers, wiring, and fuses. The formula depends on whether your circuit is DC, single phase AC, or three phase AC.
Conversion Formula
For DC: A = W/V. For AC single phase: A = W/(V × PF). For three phase: A = W/(V × PF × √3). Power factor accounts for reactive power in AC circuits.
Step-by-Step Examples
1200W, 120V, DC = 10 A
1200 / 120 = 10 amps
1200W, 120V, AC 1ph, PF=0.9 = 11.11 A
1200 / (120 × 0.9) = 11.11 amps
Frequently Asked Questions
How do I convert watts to amps?
Divide the wattage by voltage for DC circuits: A = W / V. For AC single phase, also divide by power factor: A = W / (V × PF). For three phase, divide by V × PF × √3.
What is power factor and why does it matter?
Power factor (PF) is a number between 0 and 1 that describes how efficiently a load converts electrical power. A PF of 1.0 means all power is used; lower values mean some power is returned to the source unused. Motors and fluorescent lights typically have PF of 0.8-0.95.
What is the difference between DC and AC current conversion?
DC conversions use a simple ratio (A = W/V). AC circuits have a reactive component that reduces efficiency, so you must account for power factor. Three phase systems also divide by √3 because power is shared across three conductors.