FigureDesk

Amps to Watts Calculator

Convert current in amps to power in watts for DC, single-phase AC, or three-phase AC.

Your numbers

A
V

Result

Real power

1,200 W

Apparent power
1,200 VA
Power factor used
1

P = V × I = 120 × 10 = 1200

How it works

DC and purely resistive AC use P = V × I. For AC, that product is apparent power in volt-amperes (VA) — the actual real power in watts is lower whenever power factor is below 1, because part of the current does no real work. Single-phase uses P = V × I × PF and three-phase uses P = √3 × V × I × PF.

Important assumptions

  • Power factor defaults to 1.0 (purely resistive) if left blank — most real AC loads run lower.
  • Three-phase assumes a balanced load and line-to-line voltage.
  • VA and W are the same value only when power factor is exactly 1.

FAQ

My breaker or panel is rated in amps — how do I know the wattage?

Multiply amps by voltage (and by power factor for AC loads). A 15 A, 120 V DC or purely resistive circuit is 1,800 W; the same current on a 0.9 power factor AC load delivers only 1,620 W of real power.

Why is real power lower than apparent power (VA)?

Apparent power (VA) is just voltage times current. Real power (W) is the portion actually doing work. The gap between them is the reactive power consumed by motors, transformers, and other inductive loads — accounted for by power factor.

Is this the same for DC?

For DC there is no power factor to consider — watts equals volts times amps directly. Select DC and the power factor field disappears.

FigureDesk results are advisory and do not replace a licensed electrician, a qualified engineer, or the applicable local electrical code. Verify any electrical work against your local code and with a qualified professional before relying on it.