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Electrical calculator

Watts to Amps Calculator

Convert watts to amps (and reverse) for DC, single-phase, and three-phase circuits. Power factor and voltage inputs included for AC loads. Try it free.

Instant result
Result
—

Enter values to calculate.

Inputs—
Mode—
Formula—
Trust summary CVP VERIFIED · CVP protocol 1.0.0-proposed · Engineering assurance
Input interpretation
Enter values to calculate.
Result
—
Assurance
Engineering
Declared partition coverage
PASS · 2/2 declared partitions (watts-amps, invalid-domain) · Matrix
Known limitations
  • DC / 1φ / 3φ LL
  • Core CVP does not include live graph, viewport, or pointer interaction.
Model
Current from real power and voltage (or power from current) for DC, single-phase AC, and three-phase L-L.
Scope
Balanced three-phase when 3φ (L-L) is selected.
Verification
Engine tested · Source checked · v1.4.1 · CVP VERIFIED · CVP protocol 1.0.0-proposed · Engineering assurance· View Manifest · CVP overview · Specification
Versions
Calculation 1.4.1 · CVP protocol 1.0.0-proposed
CVP identity
8/8 property · digest 8b431c133176
Legacy regression
24/24 tests · Production surface contract 4/4
Reference
O1 model · O2 expected_values · O2 numerical_behavior
Interfaces
PASS · UI (SSR) / REST / MCP — ui-ssr is query-result HTML, not a live browser session.
Supplemental domain review
Not performed
Named expert review
Not performed
CVP suite
1/1 golden · 4/4 CVP boundary · 2/2 invalid · 8/8 property · 1/1 cross-interface · 1/1 CVP contract · Manifest
Sources
Sources
Evidence
12 legacy golden · 4 legacy boundary · legacy regression suite · 1/1 oracle-backed golden · 2/2 invalid · Artifact integrity PASS
This calculator CURRENT · Public schema 1.4.1 matches · Semantic contract ✓ · Production attested · Public/cache ✓ · Origin ✓
Semantic contract
PASS
Full verification

Manifest identity, reference classes, interfaces, suite, and production records.

Formulas

Core equations used by this calculator.

DCI = P ÷ V
AC single-phaseI = P ÷ (V × PF)
AC three-phase (L-L)I = P ÷ (√3 × V × PF)
AC three-phase (L-N)I = P ÷ (3 × V × PF)
Amps → watts (DC)P = I × V
Amps → watts (3φ L-L)P = √3 × I × V × PF
iEnter real power in watts (kW × 1000). For three-phase use line-to-line RMS voltage. Resistive loads: PF = 1. Motors and many AC loads: use nameplate PF (often 0.8–0.9).

How to use

1

Choose direction and circuit

Watts → Amps or Amps → Watts, then DC, AC 1φ, or AC 3φ.

2

Enter power (or current) and voltage

For AC, enter power factor. For 3φ use line-to-line volts.

3

Read amps or watts

Use the result to check breakers, cords, and generator headroom — leave margin for safety.

Example calculations

Common configurations with formula and result.

ϟ

1000 W heater · 120 V

DC / resistive AC · PF 1

1000 ÷ 120
8.333 A
ϟ

2400 W · 240 V

Resistive

2400 ÷ 240
10 A
ϟ

AC 1φ with PF

2000 W · 110 V · PF 0.8

2000 ÷ (110 × 0.8)
22.727 A
ϟ

3φ motor

10000 W · 400 V · PF 0.9

10000 ÷ (√3 × 400 × 0.9)
16.04 A
ϟ

DC solar panel

60 W · 12 V

60 ÷ 12
5 A
ϟ

Amps → watts

12.5 A · 120 V · DC/resistive

12.5 × 120
1500 W

Watts → amps at 120 V (PF = 1)

Common values at a glance.

Power120 V240 V
100 W0.833 A0.417 A
500 W4.17 A2.08 A
1000 W8.33 A4.17 A
1500 W12.5 A6.25 A
2000 W16.67 A8.33 A
5000 W41.67 A20.83 A
i Resistive loads only (PF = 1). For motors, divide by PF as well — current rises when PF < 1.

Watts to Amps calculator specification

Version 1.4.1 · Engine tested

Calculation status

Review policy · Evidence

Definition
Watts measure real power; amps measure current. To convert watts to amps you need voltage — and for AC, power factor. DC: I = P/V. Single-phase AC: I = P/(V×PF). Three-phase (line-to-line): I = P/(√3×V×PF). Reverse with P = I×V (×PF and √3 for AC). Essential for breaker, wire, and generator sizing.
What it calculates
Current from real power and voltage (or power from current) for DC, single-phase AC, and three-phase L-L.
Inputs
  • Power P (W) or current I (A)
  • Voltage V (V); line-to-line for 3φ
  • Power factor PF for AC (hidden for DC)
  • Circuit: DC, AC 1φ, or AC 3φ
Outputs
  • Current in amperes (Watts → Amps)
  • Power in watts (Amps → Watts)
Formula
DC I=P/V; 1φ I=P/(V·PF); 3φ I=P/(√3·V·PF)
Assumptions
  • Balanced three-phase when 3φ (L-L) is selected.
  • Voltage and current are RMS for AC.
  • DC forces PF = 1; AC uses total power factor λ on real power.
Units
  • W, V, PF → A
Boundary conditions
  • Zero voltage yields 0 A (or 0 W in reverse) in the shared engine — soft boundary, not a hard error code
  • AC power_factor ≤ 0 is treated as 1 in the shared engine; UI may clamp display differently
  • Published API schema expects volts > 0 and power_factor in (0, 1]; legacy alias pf is accepted
Example
1000 W, 120 V, DC → 8.333 A
Validation cases

14 published on this page · 24/24 tests · Production surface contract 4/4 · View evidence

  • 1000 W, 120 V, DC → 8.333 A
  • 2400 W, 240 V, DC → 10 A
  • 2000 W, 110 V, PF 0.8, 1φ → 22.727 A
  • 10000 W, 400 V, PF 0.9, 3φ → 16.04 A
  • 60 W, 12 V, DC → 5 A
  • 8.333 A, 120 V, DC → W → 1000 W
  • 12.5 A, 120 V, DC → W → 1500 W
  • 2000 W, 230 V, PF 0.8, 1φ → 10.870 A
  • 2000 W, 120 V, DC (2× power vs 1000 W) → 16.667 A (linear in P at fixed V)
  • 1000 W, 240 V, DC (2× voltage) → 4.167 A (I halves when V doubles)
  • 1000 W, 0 V, DC → 0 A (soft: zero voltage → zero current)
  • 0 W, 120 V, DC → 0 A
  • 2000 W, 110 V, PF 0, 1φ → 18.182 A (engine treats PF ≤ 0 as 1)
  • 16.04 A, 400 V, PF 0.9, 3φ → W → ≈10000 W (round-trip)
Sources
Calculation version
1.4.1

Background

Interpretation and common distinctions.

Convert watts (W) to amps (A) — or the reverse — for DC, single-phase AC, and three-phase AC.

You always need voltage. For AC you also need power factor (PF).

Default check: 1000 W ÷ 120 V = 8.333 A (resistive / DC).

Quick charts (PF = 1)

AC household

Power @ 120 V @ 240 V
100 W 0.83 A 0.42 A
1000 W 8.33 A 4.17 A
1500 W 12.5 A 6.25 A
2000 W 16.7 A 8.33 A

DC / battery

Power @ 12 V @ 24 V @ 48 V
100 W 8.33 A 4.17 A 2.08 A
500 W 41.7 A 20.8 A 10.4 A
1000 W 83.3 A 41.7 A 20.8 A

Typical power factor (illustrative)

Device Typical PF
Resistive heater / oven 1.00
Incandescent lamp 1.00
Fluorescent lamp 0.95
Induction motor (full load) 0.85
Induction motor (no load) 0.35
Synchronous motor 0.90

Do not rely on typical PF for precise design — use measured or nameplate values.

Safety note

Circuits and extension leads have maximum amp ratings. Overloading causes heat and fire risk. If you are unsure about household wiring, consult a qualified electrician.

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Frequently asked questions

Key distinctions behind the calculation.

How do I convert watts to amps?

Divide power by voltage (and by power factor for AC). DC: I = P/V. Single-phase AC: I = P/(V×PF). Three-phase line-to-line: I = P/(√3×V×PF).

What is the difference between watts, amps, and volts?

Volts are electrical pressure. Amps are current flow. Watts are real power — for DC, P = V×I. Higher wattage at the same voltage means higher current.

Do I need power factor?

For DC or purely resistive AC (heaters, many lamps), PF = 1 and I = P/V. Motors, compressors, and many AC loads need PF < 1, which increases current for the same watts.

What voltage should I use for three-phase?

Enter line-to-line RMS voltage with the AC 3φ option. If you only have line-to-neutral, use I = P/(3×VL-N×PF) instead.

Why convert watts to amps?

Circuits, breakers, extension cords, and generators are rated in amps. Knowing current helps avoid overloads, tripped breakers, and overheating.

Can I convert amps back to watts?

Yes — use Amps → Watts. DC: P = I×V. AC 1φ: P = I×V×PF. AC 3φ: P = √3×I×V×PF.

What if my load is in kilowatts?

Multiply kW by 1000 to get watts before entering (e.g. 1.5 kW → 1500 W), or use the amps to kW calculator.

Typical power factor values?

Resistive ≈ 1; fluorescent ≈ 0.95; induction motor full load ≈ 0.85; no-load motor can be much lower. Prefer nameplate values for design.