OneFreePlace · Tool #150

Solve watts, volts and amps with the AC details included.

Handle DC, single-phase AC and balanced three-phase AC without pretending power factor does not exist. Solve for real power, voltage or current, inspect kVA/kVAR and phase angle, compare power-factor scenarios, estimate motor input current from efficiency, and check mathematical current headroom.

✓ DC + 1φ + balanced 3φ✓ Solve W / V / A✓ kVA + kVAR + phase angle✓ PF impact lab✓ Motor efficiency mode

Watts / Volts / Amps Calculator

DC · single-phase · three-phase · PF · motor

Calculation engine

Choose what you want to solve.

Electrical systemThree-phase formulas assume a balanced system. Line-to-neutral mode is a balanced-wye calculation.

System

Power factor

Reactive direction

Single-phase AC: P = V × I × PF using RMS voltage/current.

Core solverThe selected target is calculated from the other two quantities.

Solve for

Current limit · optional

Current-limit unit

Real power

Power unit

Real power consumed or delivered.

Voltage

Voltage unit

Current

Current unit

Electrical result

Calculating

—

calculated current

Enter valid electrical quantities.

Real power P—watts / kW

Voltage V—RMS for AC

Current I—RMS for AC

Apparent power S—VA / kVA

Reactive power Q—VAR / kVAR

Power factor / angle—cos φ and phase angle

Calculation noteCalculated current is not a conductor or breaker recommendation.

Formula audit

Every result states the formula, phase multiplier and unit-normalized inputs.

System diagnostics

Three-phase results include per-phase context. Optional current limits show mathematical utilization only—not code compliance.

Power-factor sensitivity

For AC solver/motor results, see the current required for the same real power and voltage at several PF values.

PF	Current	Apparent kVA	Reactive kVAR	Current vs PF=1

Power triangle

Real power P, reactive power Q and apparent power S are related by S² = P² + Q². Leading and lagging use the same magnitudes but opposite Q direction here.

Three-phase context

Balanced three-phase line-to-line real power uses √3 × V_LL × I × PF. Balanced-wye line-to-neutral uses 3 × V_LN × I × PF.

Important limits

Balanced three-phase assumptionThe shortcut formulas used here assume equal phase magnitudes. Unbalanced systems require per-phase measurements and summation.

Model limit

RMS quantities for ACVoltage/current entries are RMS values. Harmonics and non-sinusoidal loads can require true-RMS instruments and more detailed power measurements.

Measurement matters

Not a wire or breaker sizing toolStarting current, continuous-load rules, conductor temperature, protection curves and local electrical codes are outside this calculator.

Safety boundary

Power factor changes current and apparent power for the same real kW.Improving PF can reduce current and kVA demand, but it does not automatically reduce the real watts required by the load. Do not use this calculator alone to design power-factor correction equipment.