Watts Amps Volts Calculator

By Giorgi Gaprindashvili · Updated Aug 2026

Solve watts, amps, or volts for DC, single-phase AC, and balanced three-phase AC with power factor when it matters.

Solve For

Circuit Type

Real Power

Current

Voltage

Power Factor

Power Conversion Result

Solved Value

Real Power

Current

Voltage

Apparent Power

Calculation Basis

What This Result Means

How to Use

Choose the unknown - Select watts, amps, or volts. The selected quantity is solved from the other two.
Choose the circuit - Use DC for batteries and DC systems, single-phase AC for one-phase loads, or balanced three-phase AC when the voltage entered is line-to-line.
Enter power factor for AC - Use the equipment or measured PF when known. A PF of 1.00 is appropriate for ideal resistive loads, but it should not be assumed for motors, drives, transformers, or many electronic loads.
Read watts and kVA separately - Watts are real power. kVA is apparent power. They are equal only when PF is 1.
Use a dedicated sizing tool next - This calculator converts electrical quantities. It does not select a breaker, conductor, generator, motor protection, or service size.

Quick answer

For DC, real power is volts × amps. For single-phase AC, multiply by power factor. For balanced three-phase AC using line-to-line voltage, multiply volts × amps × power factor × √3. Example: 480 V, 10 A, three-phase, PF 0.90 is about 7.48 kW and 8.31 kVA.

One Solver, Three Circuit Models

Circuit type changes the power equation. Power factor changes real power for AC loads.

Watts and VA Are Not the Same Thing

Watts measure real power doing useful work. Volt-amps measure apparent power, the product of RMS voltage and current with the phase multiplier included. Power factor is real power divided by apparent power.

At PF 1.00, 1,500 W equals 1,500 VA. At PF 0.80, a 1,500 W single-phase load requires 1,875 VA. That difference matters when converting watts to current or comparing a load with equipment rated in VA or kVA.

For balanced three-phase systems, this page treats the entered voltage as line-to-line voltage. If your data is phase-to-neutral, convert or use a tool built around the exact system configuration.

Worked Examples

Circuit	Inputs	Result
DC	120 V, 12.5 A	1,500 W
1-phase AC	120 V, 1,500 W, PF 0.80	15.625 A
3-phase AC	480 V, 10 A, PF 0.90	7.48 kW, 8.31 kVA
3-phase AC	10 kW, 480 V, PF 0.80	15.04 A

Examples assume balanced three-phase loads where applicable. Use actual equipment data for installed systems.

Formulas Used

The selected circuit model determines the phase multiplier and power-factor term:

DC = P = V × I
Single-phase AC = P = V × I × PF
Balanced three-phase AC = P = √3 × V × I × PF
Apparent power, single phase = S = V × I
Apparent power, three phase = S = √3 × V × I

The calculator algebraically rearranges the applicable equation when amps or volts is the unknown.

Technical Source

Fluke explains power factor as the ratio of real power to apparent power and distinguishes kW from kVA in AC systems.Fluke - Power Factor: What it is and How to Calculate it

Next Steps

Use the solved value in the tool that matches the next decision:

Combine several equipment loadsTotal multiple W or VA entries and convert the combined load to current.
Size a conductorCheck ampacity and optional voltage drop rather than treating current conversion as wire sizing.
Screen an OCPD planning sizeSplit continuous and noncontinuous current before selecting a standard rating.

Related Calculators

Power Factor CalculatorSolve PF, kVA, kVAR, phase angle, or correction when AC power relationships are the next question.kVA to Amps CalculatorConvert apparent power and voltage directly between kVA and line current.Ohm's Law CalculatorAdd resistance to the voltage-current-power relationship.Voltage Drop CalculatorApply the solved current to a conductor run over distance.

Need to move from power conversion to circuit sizing? Browse the electrical calculator collection.

FAQ

How do I calculate amps from watts?

For DC, amps = watts ÷ volts. For single-phase AC, amps = watts ÷ (volts × PF). For balanced three-phase AC using line-to-line voltage, amps = watts ÷ (√3 × volts × PF).

Why does three-phase use √3?

For a balanced three-phase system using line-to-line voltage, total apparent power is √3 × V × I. Real power adds the power-factor term.

What power factor should I enter?

Use the equipment nameplate, manufacturer data, or a measured value when available. Do not guess 1.00 for motors, drives, transformers, or other non-resistive AC loads.

Can I use this to size a breaker or wire?

Not by itself. The solved current is one input. Breaker and conductor sizing require load treatment, ampacity rules, installation conditions, voltage drop, equipment instructions, and the code adopted for the project.

Updated Aug 2026 · See our Methodology

Electrical power-conversion tool only. Three-phase results assume a balanced system and line-to-line voltage. Use actual power factor and equipment data where applicable. This calculator does not determine code compliance, conductor ampacity, overcurrent protection, motor protection, service size, or equipment suitability.