Electrical Calculator
Amps to Watts Calculator
Convert amps to watts using voltage and current type for DC, single-phase, and three-phase electrical loads.
What this calculator does
This amps to watts calculator helps you estimate power in watts from current and voltage. It supports DC, single-phase AC, and three-phase AC calculations.
It is useful when checking circuits, comparing equipment ratings, estimating load power, or turning nameplate current values into watt and kilowatt figures.
Inputs
Result
How amps to watts works
In a DC circuit, watts are simply amps multiplied by volts. In AC circuits, power factor matters, and three-phase systems also include the √3 factor.
That means the same current can produce different watt values depending on voltage, power factor, and whether the system is single-phase or three-phase.
Formulas
DC watts = amps × volts
Single-phase watts = amps × volts × power factor
Three-phase watts = √3 × amps × volts × power factor
Common amps to watts examples
15 amps to watts at 120V
15A × 120V = 1800W in a simple DC-style or resistive estimate.
20 amps to watts at 240V
20A × 240V = 4800W before any AC power factor adjustment.
10 amps to watts in 3 phase at 400V, PF 0.9
√3 × 10 × 400 × 0.9 = about 6235.38W, or about 6.2354kW.
30 amps to watts at 230V, single-phase, PF 0.95
30 × 230 × 0.95 = 6555W, or about 6.555kW.
When this calculator is useful
Equipment nameplate checks
If a device lists current but not watts, this tool helps you estimate the load power more quickly.
Generator and inverter planning
Converting amps to watts can help with rough capacity checks before sizing backup equipment.
Budgeting and energy estimates
Once you have watts, you can use the Electricity Cost Calculator for simple usage cost estimates.
FAQ
Can amps be converted directly to watts?
Not by amps alone. You also need voltage, and for AC loads you usually need power factor as well.
Why does AC use power factor?
In AC systems, real power depends on how effectively current is converted into usable work, which is what power factor represents.
Can I use this for three-phase current?
Yes. Choose the three-phase option and enter line voltage, current, and power factor for a balanced system estimate.
What is the next step after watts?
After estimating watts, you can compare power in kilowatts, estimate energy cost, or convert between related units such as kW and HP.