Amps to Watts Conversion Calculator
Enter the current and voltage to convert amps to watts for DC and AC single and three-phase circuits.
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How to Convert Amps to Watts
Converting amps to watts can be done using the Watt’s Law power formula, which states that I = P ÷ V, where P is power measured in watts, I is current measured in amps, and V is voltage measured in volts.
Multiplying each side of the equation by the voltage V, it is possible to express the amps to watts formula as:[1]
P(W) = I(A) × V(V)
Thus, the power P in watts is equal to the current I in amps multiplied by the voltage V in volts.
For example, find the wattage of 8 amps at 120 volts
P(W) = 8 A × 120 V
P(W) = 960 W
So, the power at this current and voltage is to 960 watts.
Single-Phase AC Circuit Amps to Watts Conversion
Converting amps to watts for a single-phase AC circuit with power factor requires a slight variation of the formula.
P(W) = I(A) × V(V) × PF
The power P in watts is equal to the current I in amps multiplied by the voltage V in volts multiplied by the power factor PF.
AC electrical power is composed of a real part expressed in watts, and a reactive part expressed in volt-amps. The magnitude of both real and reactive together is called the apparent power, and the PF gives the ratio of real power to apparent power.[2]
The power factor is determined by the alternating current frequency and the inductive or capacitive elements in the circuit.
If you’re trying to calculate PF from power, current, and voltage, we suggest using a power factor calculator to find the PF value.
Three-Phase AC Circuit Amps to Watts Conversion
Using Line to Line Voltage
For three-phase AC circuits where the current, line to line RMS voltage, and power factor are known, the formula to convert amps to watts is:
P(W) = I(A) × VL-L(V) × PF × √3
The power P in watts is equal to the current I in amps multiplied by the voltage V in volts multiplied by the power factor PF multiplied by the square root of 3.
This equation calculates the power for one pair of wires in a three-phase system, but you’ll need to multiply it by three when considering all three pairs of wires in a three-phase system.
Using Line to Neutral Voltage
For three-phase AC circuits where the current, line to neutral RMS voltage, and power factor are known, the formula to convert amps to watts is:
P(W) = I(A) × VL-N(V) × PF × 3
The power P in watts is equal to the current I in amps multiplied by the voltage V in volts multiplied by the power factor PF multiplied by 3.
This formula calculates the power delivered by all three wires in a three-phase system, but you’ll need to divide by three if you’re considering a single wire in the three-phase system.
How to Convert Amps and Ohms to Watts
You can also convert amps to watts using circuit resistance with this formula:[1]
P(W) = I(A)2 × R(Ω)
The power P in watts is equal to the current I in amps squared multiplied by the resistance R in ohms.
Since 1 kilowatt is equal to 1,000 watts, it is possible to use the formulas above to also convert amps to kW, but the result will need to be divided by 1,000. You can also use our amps to kW calculator to solve for kilowatts.
Equivalent Amps and Watts at 120V
| Current (Amps) | Power (Watts) | RMS Voltage |
|---|---|---|
| 1 amps | 120 watts | 120 volts |
| 2 amps | 240 watts | 120 volts |
| 3 amps | 360 watts | 120 volts |
| 4 amps | 480 watts | 120 volts |
| 5 amps | 600 watts | 120 volts |
| 6 amps | 720 watts | 120 volts |
| 7 amps | 840 watts | 120 volts |
| 8 amps | 960 watts | 120 volts |
| 9 amps | 1,080 watts | 120 volts |
| 10 amps | 1,200 watts | 120 volts |
| 11 amps | 1,320 watts | 120 volts |
| 12 amps | 1,440 watts | 120 volts |
| 13 amps | 1,560 watts | 120 volts |
| 14 amps | 1,680 watts | 120 volts |
| 15 amps | 1,800 watts | 120 volts |
| 20 amps | 2,400 watts | 120 volts |
| 25 amps | 3,000 watts | 120 volts |
| 30 amps | 3,600 watts | 120 volts |
| 35 amps | 4,200 watts | 120 volts |
| 40 amps | 4,800 watts | 120 volts |
| 45 amps | 5,400 watts | 120 volts |
| 50 amps | 6,000 watts | 120 volts |
| 60 amps | 7,200 watts | 120 volts |
| 70 amps | 8,400 watts | 120 volts |
| 80 amps | 9,600 watts | 120 volts |
| 90 amps | 10,800 watts | 120 volts |
| 100 amps | 12,000 watts | 120 volts |
Equivalent Amps and Watts at 12V
| Current (Amps) | Power (Watts) | RMS Voltage |
|---|---|---|
| 1 amps | 12 watts | 12 volts |
| 2 amps | 24 watts | 12 volts |
| 3 amps | 36 watts | 12 volts |
| 4 amps | 48 watts | 12 volts |
| 5 amps | 60 watts | 12 volts |
| 6 amps | 72 watts | 12 volts |
| 7 amps | 84 watts | 12 volts |
| 8 amps | 96 watts | 12 volts |
| 9 amps | 108 watts | 12 volts |
| 10 amps | 120 watts | 12 volts |
| 11 amps | 132 watts | 12 volts |
| 12 amps | 144 watts | 12 volts |
| 13 amps | 156 watts | 12 volts |
| 14 amps | 168 watts | 12 volts |
| 15 amps | 180 watts | 12 volts |
| 20 amps | 240 watts | 12 volts |
| 25 amps | 300 watts | 12 volts |
| 30 amps | 360 watts | 12 volts |
| 35 amps | 420 watts | 12 volts |
| 40 amps | 480 watts | 12 volts |
| 45 amps | 540 watts | 12 volts |
| 50 amps | 600 watts | 12 volts |
| 60 amps | 720 watts | 12 volts |
| 70 amps | 840 watts | 12 volts |
| 80 amps | 960 watts | 12 volts |
| 90 amps | 1,080 watts | 12 volts |
| 100 amps | 1,200 watts | 12 volts |
You might also be interest in our watts to amps calculator.
References
- Miller, C., NFPA's Electrical References, National Fire Protection Association, 2004, Jones & Bartlett Learning, 67-75. https://www.google.com/books/edition/NFPA_s_Electrical_References/raUyIi7i-asC
- Fiore, J., AC Electrical Circuit Analysis - A Practical Approach, 2022, 274. http://www.dissidents.com/resources/ACElectricalCircuitAnalysis.pdf