瓦特、伏特、安培換算

How to use this calculator

1. Choose the current type: DC, AC single-phase or AC three-phase.
2. For AC, enter the power factor (use 1 for resistive loads).
3. Enter any two of watts, volts and amps; leave the third blank.
4. Click Convert to get the missing value.

Watts, volts and amps formulas

The three are linked by electrical power:

So to find current: A = W / (V × PF) (single-phase) or A = W / (√3 × V × PF) (three-phase). For DC, set PF = 1.

Example: watts to amps

A 1500 W heater on 120 V DC draws 1500 / 120 = 12.5 A. The same 1500 W on 230 V single-phase AC at PF 1.0 draws about 6.5 A.

Quick reference: watts to amps

Single-phase at power factor 1.0 (resistive). Divide by the power factor for inductive loads.

常見問題

How many amps is 1500 watts?

At 120 V it is about 12.5 A; at 230 V about 6.5 A (resistive load, PF 1.0).

How do I convert watts to amps?

Amps = watts ÷ (volts × power factor). For DC or resistive AC the power factor is 1.

Why does power factor matter?

For inductive AC loads (motors, transformers) the current is higher than watts ÷ volts alone, because part of the current is reactive.