Alternating current

AC Amps to Watts Calculator

W = A × V × PF

AC Amps to Watts Calculator

Select Single-Phase or Three-Phase to calculate AC electrical power.

Live Result
Formula-backed — instant professional result
System Type
CALCULATED POWER
0 W
Also equals 0 kW
Formula used W = A × V × PF The primary result is shown in W using the formula displayed above. 10A × 120V × 1.0 = 1200W

This calculator is an educational planning estimate. Verify safety-critical work with equipment nameplate data, local electrical code, and a qualified professional.

Convert AC amps to watts with voltage and power factor. Single-phase: W = A × V × PF. Three-phase: W = 1.732 × A × V × PF. Free tool.

AC amps to watts

Single-phase AC load path

Convert AC amps to watts with voltage and power factor. Single-phase: W = A × V × PF. Three-phase: W = 1.732 × A × V × PF. Free tool.

120V single-phase formula-first page-specific visual

AC Amps to Watts Calculator — Single & 3 Phase | Ampstowatt Guide

Single-phase AC path

Current, voltage, and power factor feeding a real watt result

AC pages need power factor context, so the visual connects outlet voltage, current draw, PF, and breaker planning.

Formula Single phase: W = A x V x PF. Three phase: W = 1.732 x A x V x PF
AC Amps to Watts Calculator — Single & 3 Phase | Ampstowatt technical circuit diagram A premium electrical diagram showing the main values and conversion flow for AC Amps to Watts Calculator — Single & 3 Phase | Ampstowatt. AC source 120 V 10 A PF 0.90 Load 1,080 W
AC Amps to Watts Calculator — Single & 3 Phase | Ampstowatt Single-phase AC path with real formula values and planning checkpoints.

Quick answer

Use this calculator to convert AC current into real watts with voltage and power factor.

Single-phase AC loads can be resistive or inductive. Resistive loads may be near PF 1.00, while motors, compressors, and HVAC equipment often need a lower power factor.

Single phase: W = A x V x PF. Three phase: W = 1.732 x A x V x PF

Inputs to check before calculating

  • Use the correct nominal voltage for the circuit.
  • Enter measured current or nameplate running current.
  • Use realistic PF for motors, compressors, and transformer loads.
  • Compare the result with breaker and continuous-load limits.

Example: 10 amps at 120 volts

At 120 volts, 10 amps equals 1,200 watts before AC power-factor adjustments. Formula: 10 A x 120 V = 1,200 W.

Best use cases

  • Single and three-phase
  • Power factor correction
  • RMS voltage workflow
  • single-phase AC load planning with clear unit labels.

Common mistake to avoid

Do not use DC-style amps x volts for every AC load when the equipment has a lower power factor.

How to use the result

Use the watt result for appliance planning, branch-circuit checks, and comparison with the main amps to watts formula.

Accuracy and safety note

Calculator output is a planning estimate. Final breaker sizing, wire gauge, derating, voltage-drop limits, equipment protection, and code compliance should be verified with manufacturer documentation and a qualified electrician or engineer.

For the broad formula, reference table, and breaker planning context, start with the main Amps to Watts Calculator.

Related Amps to Watts Calculators

Start with the main conversion tool

Move between AC, DC, phase-specific, formula, chart, and reverse conversion pages without using redirected URLs.Amps to Watts Calculator

Methodology, Review Notes, and Sources

How this calculator works

The calculator applies Watt's law for DC and resistive loads, then adds power factor for AC loads and the 1.732 multiplier for balanced three-phase line-to-line calculations.

  • DC and resistive loads: W = A x V
  • Single-phase AC: W = A x V x PF
  • Three-phase AC: W = 1.732 x A x V x PF

Editorial review

Last reviewed: June 26, 2026. Ampstowatt.com is built around the amps to watts conversion — our core specialty. Content is maintained by the Ampstowatt editorial team and checked for formula consistency, unit labels, calculator behavior, and safety wording.

The page is an educational planning reference, not a licensed electrical design or inspection service.

Reference sources

FAQ

AC Calculator FAQ

Fast answers before you use the calculator or compare formulas.

W How do I convert AC amps to watts at 120V?

For single-phase AC: Watts = Amps × 120 × Power Factor. For pure resistive loads (PF = 1.0), it simplifies to Watts = Amps × 120. Example: 10A at 120V with PF 0.90 = 1080 watts real power.

VA What is the difference between real watts and apparent power (VA)?

Real watts (W) represent usable power that does actual work — heat, light, motion. Apparent power (VA) is the total current × voltage drawn from the supply, including reactive current that does no useful work. The ratio is power factor: Watts = VA × PF. A 1,000 VA UPS at PF 0.80 delivers only 800W of real power.

PF Why are my AC watts lower than amps × volts?

Because inductive loads (motors, compressors, transformers) draw reactive current that oscillates between the source and load without doing useful work. This lowers the power factor below 1.00, so real watts are less than the simple amps × volts product. Only resistive loads (heaters, incandescent lamps) give watts equal to amps × volts.

MTR How do I measure power factor?

You can measure PF with a power quality meter or clamp meter that reads both watts and VA simultaneously. PF = Watts ÷ VA. Alternatively, check the equipment nameplate — most motors, compressors, and industrial equipment list PF at rated load. If unknown, 0.85 is a conservative estimate for motor loads.

HOME Can I just ignore power factor for household circuits?

For most residential calculations, yes. Household resistive loads (lights, heaters, toasters) have PF very close to 1.00. But for whole-house load calculations that include HVAC compressors, well pumps, and refrigerators, ignoring PF will overestimate real power by 10–20%. For generator sizing, always account for PF.

CAL Does this calculator work for both 120V and other voltages?

Yes — you can change the voltage field to any value. The calculator applies the correct formula for DC, AC single-phase, or AC three-phase regardless of voltage. This page defaults to 120V for convenience, but the formula works for 12V, 24V, 48V, 208V, 480V, or any other voltage.