electrical tool
Amps to Watts Calculator
Convert current into watts for DC, single-phase, or three-phase systems.
For three-phase AC, voltage is treated as line-to-line voltage. DC uses PF = 1; AC power factor is limited to 0.01–1.
Calculated power
1080 W
P = V × I × PF.
Amps to watts guide
How to convert amps to watts
Watts describe real electrical power. Amps describe current. To convert current into power, combine the current with voltage and, for AC systems, power factor and phase configuration.
Formulas by system type
DC
W = V × A
Single-phase AC
W = V × A × PF
Three-phase AC
W = √3 × V × A × PF
Worked examples
DC: 10 A × 120 V = 1,200 W.
Single-phase AC: 10 A × 120 V × 0.8 PF = 960 W.
Three-phase AC: √3 × 10 A × 240 V × 0.9 PF ≈ 3,741 W.
Quick reference at PF = 1
| Amps | 120 V single-phase | 240 V single-phase |
|---|---|---|
| 5 A | 600 W | 1200 W |
| 10 A | 1200 W | 2400 W |
| 15 A | 1800 W | 3600 W |
| 20 A | 2400 W | 4800 W |
Practical uses and limits
This conversion helps compare a current reading with a known voltage, estimate load power, and cross-check equipment documentation. It does not establish wiring, breaker, or connection requirements.
Frequently asked questions
How do I convert amps to watts?
Multiply amps by volts for DC. For single-phase AC, multiply amps by volts and power factor. For three-phase AC, multiply amps by √3, line-to-line volts, and power factor.
Why does power factor affect watts?
AC power factor represents how effectively current is converted into real power. A lower power factor means the same current and voltage produce fewer real watts.
What voltage does the three-phase formula use?
This page treats the three-phase input as line-to-line voltage.
Can I use this result as an equipment rating?
Use it as a calculation estimate. Confirm equipment nameplate data, system type, voltage, and manufacturer requirements before making an installation decision.
Important assumptions
This is a planning estimate, not a guarantee of performance. Real equipment varies with temperature, age, power quality, duty cycle, wiring, and manufacturer specifications.