Calculate watts from amps or amps from watts for DC, single-phase AC, and three-phase AC circuits with voltage and power factor.
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| Calculator Operations | Required Inputs |
|---|---|
| Convert Amps to Watts (AC) | Current, voltage, power factor and phase basis |
| Convert Watts and Volts to Amps | Watts, Volts |
| Convert Volts and Amps to Watts | Volts, Amps |
Amps to Watts Formula
The equation below applies to DC and single-phase AC with power factor 1. For single-phase AC use P = V × I × PF. For balanced three-phase loads use P = √3 × VLL × I × PF, or P = 3 × VLN × I × PF for balanced Wye line-to-neutral values. Use RMS AC voltage/current and true power factor; this does not size wiring or protection.
- Where P is power in watts
- I is the current in amps
- V is the voltage in volts
For DC, multiply amps by volts. For AC, also apply the true power factor and the correct phase factor.
| Amps (A) | Watts (W) at 5 V | Watts (W) at 12 V | Watts (W) at 24 V | Watts (W) at 120 V | Watts (W) at 230 V |
|---|---|---|---|---|---|
| 0.1 | 0.5 | 1.2 | 2.4 | 12 | 23 |
| 0.2 | 1 | 2.4 | 4.8 | 24 | 46 |
| 0.5 | 2.5 | 6 | 12 | 60 | 115 |
| 0.75 | 3.75 | 9 | 18 | 90 | 172.5 |
| 1 | 5 | 12 | 24 | 120 | 230 |
| 1.5 | 7.5 | 18 | 36 | 180 | 345 |
| 2 | 10 | 24 | 48 | 240 | 460 |
| 2.5 | 12.5 | 30 | 60 | 300 | 575 |
| 3 | 15 | 36 | 72 | 360 | 690 |
| 5 | 25 | 60 | 120 | 600 | 1150 |
| 7.5 | 37.5 | 90 | 180 | 900 | 1725 |
| 10 | 50 | 120 | 240 | 1200 | 2300 |
| 12 | 60 | 144 | 288 | 1440 | 2760 |
| 15 | 75 | 180 | 360 | 1800 | 3450 |
| 20 | 100 | 240 | 480 | 2400 | 4600 |
| 25 | 125 | 300 | 600 | 3000 | 5750 |
| 30 | 150 | 360 | 720 | 3600 | 6900 |
| 40 | 200 | 480 | 960 | 4800 | 9200 |
| 50 | 250 | 600 | 1200 | 6000 | 11500 |
| 60 | 300 | 720 | 1440 | 7200 | 13800 |
| Assumes power factor (pf) = 1 (DC or purely resistive load). Formula: P (W) = V (V) × I (A). Common voltages shown: 5 V (USB), 12 V (automotive), 24 V (industrial/PoE), 120 V (NA mains), 230 V (EU mains). | |||||
Amps to Watts Definition
Converting amps to watts requires voltage and the circuit basis. DC uses P = VI; AC additionally requires true power factor and, for balanced three-phase loads, the selected line-to-line or line-to-neutral factor.
Amps to Watts Example
How to calculate watts from amps
- First, determine the total current
Measure or calculate the total current of the circuit in amps.
- Next, determine the total voltage
Using a voltmeter or equation, calculate the total volts of the circuit.
- Finally, calculate the power
Calculate the power, also known as the total number of watts.
FAQ
Watts are a measure used in physics to represent total electric power. This value is derived from the current and electric potential of the system.
