Amp to W calculator
Convert current to watts and see where the result sits between a phone charger and a whole house.
Inputs
Watts on a scale of everyday devices
How amp to W calculator works
The amp to W calculator converts current in amperes (A) into power in watts (W) with 3 inputs: current, voltage and current type, plus power factor for alternating current (AC). The log scale places the result between a 5 W phone charger and a 100 kW workshop.
W = k × I × V × PF5 A at 230 V gives 1,150 W (1.15 kW), the power of a hair dryer on low.
Amp to W formula
The amp to W formula is W = A × V for direct current (DC). There are 3 amp to W formulas: DC, single-phase AC and three-phase AC.
Direct current (DC)
W = I × V2.1 A × 5 V = 10.5 W
Single-phase AC
W = I × V × PF5 A × 230 V × 1 = 1,150 W
Three-phase AC
W = √3 × I × V × PF1.732 × 10 A × 400 V × 0.9 = 6,235 W
The watt is named after James Watt. 1 W equals 1 joule per second (J/s), and 1,000 W equals 1 kilowatt (kW).
Amp to W conversion chart
The amp to W conversion chart lists 12 currents from 0.1 A to 50 A at 6 voltages: 5 V, 12 V and 24 V DC and 120 V, 230 V and 240 V AC.
| Amps | 5 VDC | 12 VDC | 24 VDC | 120 VAC | 230 VAC | 240 VAC |
|---|---|---|---|---|---|---|
| 0.1 A | 0.5 | 1.2 | 2.4 | 12 | 23 | 24 |
| 0.5 A | 2.5 | 6 | 12 | 60 | 115 | 120 |
| 1 A | 5 | 12 | 24 | 120 | 230 | 240 |
| 2 A | 10 | 24 | 48 | 240 | 460 | 480 |
| 3 A | 15 | 36 | 72 | 360 | 690 | 720 |
| 5 A | 25 | 60 | 120 | 600 | 1,150 | 1,200 |
| 10 A | 50 | 120 | 240 | 1,200 | 2,300 | 2,400 |
| 13 A | 65 | 156 | 312 | 1,560 | 2,990 | 3,120 |
| 15 A | 75 | 180 | 360 | 1,800 | 3,450 | 3,600 |
| 16 A | 80 | 192 | 384 | 1,920 | 3,680 | 3,840 |
| 20 A | 100 | 240 | 480 | 2,400 | 4,600 | 4,800 |
| 50 A | 250 | 600 | 1,200 | 6,000 | 11,500 | 12,000 |
15 A at 120 V is 1,800 W, the limit of a standard North American 15 A circuit, with 1,440 W allowed for continuous loads.
Amp to W Excel formula
The amp to W Excel formula is =A2*B2*C2 with amps in A2, volts in B2 and power factor in C2. Use =A2*B2 for DC.
| A | B | C | D | E | |
|---|---|---|---|---|---|
| 1 | Amps | Volts | PF | Watts | Formula in D |
| 2 | 5 | 230 | 1 | 1,150 | =A2*B2*C2 |
| 3 | 2.1 | 5 | 1 | 10.5 | =A3*B3*C3 |
| 4 | 10 | 400 | 0.9 | 6,235.38 | =ROUND(SQRT(3)*A4*B4*C4,0) |
Divide column D by 1,000 in column E to get kilowatts.
Amp to W equation
The amp to W equation is P = I × V × PF, where P is power in watts.
- W
- Power in watts
- I
- Current in amperes (A)
- V
- Voltage in volts (V)
- PF
- Power factor, 1 for DC
Watts equal amps × volts for DC and for resistive AC loads at power factor 1.
Amp to W FAQ
How many watts is 1 amp?
1 amp is 230 W at 230 V, 120 W at 120 V and 12 W at 12 V, at a power factor of 1.
How many watts is 2.1 amps at 5 V?
2.1 amps at 5 V is 10.5 W, the output of a standard USB charger.
How many watts is 15 amps at 120V?
15 amps at 120V is 1,800 W, with 1,440 W allowed for continuous loads at 80%.
Is watts amps times volts?
Yes, watts equal amps times volts for DC and resistive AC loads. Other AC loads multiply by the power factor: 5 A × 230 V × 0.8 = 920 W.