⚡ Free Tool

AC Wattage Calculator

Calculate real power (watts), apparent power (VA), and reactive power (VAR) for single-phase and three-phase AC circuits. Enter voltage, current, and power factor to get instant results — with formulas, power triangle breakdown, and appliance reference tables.

How to Calculate AC Wattage

AC wattage (real power) depends on three variables: voltage, current, and power factor. Unlike DC circuits where P = V × I is all you need, AC circuits require the power factor to account for the phase difference between voltage and current waveforms. This calculator handles both single-phase and three-phase AC automatically.

1

Choose Phase Type

Select single-phase AC (homes, offices) or three-phase AC (industrial, large motors). Each uses a different formula for accurate results.

2

Enter Voltage & Current

Input the RMS voltage and RMS current. Use presets for common supply voltages (120V, 230V, 415V). Select power factor using load-type presets.

3

Get Full Power Breakdown

Instantly see real power (W), apparent power (VA), reactive power (VAR), phase angle, and a visual power triangle — all in one place.

AC Wattage Formulas

The core AC power formulas involve three types of power that together form the "power triangle". Understanding all three gives you the complete picture of what your circuit is doing.

Single-Phase AC — Real Power
P = V × I × PF
P = Real power (watts, W)
V = RMS voltage (volts, V)
I = RMS current (amps, A)
PF = Power factor (0–1)
Three-Phase AC — Real Power
P = √3 × VLL × I × PF
√3 = 1.7321 (three-phase constant)
VLL = Line-to-line voltage
I = Line current (amps)
PF = cos(φ), the power factor angle
Apparent Power (S) — Both Phase Types
S = V × I   /   S = √3 × VLL × I
Apparent power (VA) = Real power ÷ Power factor: S = P / PF
This is the total power the supply must deliver
Reactive Power (Q) — Power Triangle
Q = √(S² − P²)
Q = Reactive power (VAR — volt-ampere reactive)
Also: Q = S × sin(φ), where φ = arccos(PF)
Power Triangle: S² = P² + Q²

Understanding Real, Apparent, and Reactive Power

The three types of AC power form a right triangle — the power triangle — which is the most important concept in AC electrical engineering. If you've ever wondered why your utility bill is measured in kWh (real power) but your generator is rated in kVA (apparent power), this is why.

Real Power (P) — Measured in Watts (W) or kW

Real power is the actual useful power consumed by a load. It converts electrical energy into heat, light, or mechanical work. This is what your electricity meter measures and what you pay for. Resistive loads (heaters, incandescent bulbs, ovens) consume only real power with PF = 1.0.

Apparent Power (S) — Measured in Volt-Amperes (VA) or kVA

Apparent power is the total power the electrical supply must provide. It equals Voltage × Current — the full product before accounting for phase difference. Generators, UPS systems, and transformers are rated in kVA because they must supply the total apparent power, regardless of power factor. If you connect a motor with PF = 0.8 to a 10 kVA generator, you only get 8 kW of real power output.

Reactive Power (Q) — Measured in VAR (Volt-Ampere Reactive)

Reactive power is the power that oscillates back and forth between the supply and reactive components (inductors and capacitors) in the load. It does no useful work but occupies capacity in wiring and transformers. Inductive loads (motors, transformers, fluorescent ballasts) generate positive reactive power (lag). Capacitive loads generate negative reactive power (lead). Reactive power can be cancelled by installing power factor correction capacitors — a common industrial energy efficiency measure.

🔥 Resistive Load (Heater)
PF = 1.0, φ = 0°
All apparent power = real power
Q = 0 VAR (no reactive component)
Example: 230V × 10A × 1.0 = 2,300W
⚙️ Inductive Load (Motor)
PF = 0.8, φ = 36.87°
Real power < Apparent power
Q = S × sin(36.87°) = 0.6 × S
Example: 230V × 10A × 0.8 = 1,840W (S = 2,300 VA, Q = 1,380 VAR)
🏭 Three-Phase Motor
415V, 20A, PF = 0.85, 3-phase
P = 1.732 × 415 × 20 × 0.85
= 12,232W (12.23 kW)
S = 14,385 VA, Q = 7,581 VAR
🏠 Home Split AC (1.5 Ton)
230V, 7A, PF = 0.9, single-phase
P = 230 × 7 × 0.9
= 1,449W (1.45 kW)
S = 1,610 VA — typical for Indian 1.5-ton 5-star AC

Common Appliance AC Wattage Reference Table

This table lists typical AC wattage, current draw, and power factors for common household and industrial appliances. Use these values as starting points when you don't have exact nameplate data. Always verify with the actual appliance nameplate for sizing circuit breakers and wiring.

ApplianceVoltageCurrent (A)Power FactorReal Power (W)Apparent Power (VA)
LED Bulb (10W)230V0.05A0.910W11.5 VA
Ceiling Fan230V0.3A0.855W69 VA
Laptop Charger230V0.35A0.9565W80 VA
Desktop PC230V1.5A0.9310W345 VA
Refrigerator230V1.0A0.85196W230 VA
Microwave Oven230V5.5A0.981,238W1,265 VA
Split AC (1 Ton)230V5.5A0.91,139W1,265 VA
Split AC (1.5 Ton)230V7.0A0.91,449W1,610 VA
Split AC (2 Ton)230V9.5A0.91,967W2,185 VA
Washing Machine230V4.0A0.85782W920 VA
Water Heater (Geyser)230V8.7A1.02,000W2,000 VA
Electric Kettle230V6.5A1.01,500W1,500 VA
Hair Dryer230V8.7A0.951,900W2,000 VA
Induction Cooktop230V8.7A0.981,960W2,000 VA
Industrial Motor (5HP)415V 3φ7.6A0.853,730W5,467 VA
Industrial Motor (10HP)415V 3φ15A0.859,138W10,750 VA

AC Wattage Conversion Table (Single-Phase)

Pre-calculated real power values for common voltage, current, and power factor combinations. Use this quick reference when you need to verify calculations without running the calculator. All values use single-phase AC formula: W = V × I × PF.

Amps120V (PF=1)120V (PF=0.8)230V (PF=1)230V (PF=0.8)240V (PF=1)240V (PF=0.8)
1 A120 W96 W230 W184 W240 W192 W
2 A240 W192 W460 W368 W480 W384 W
5 A600 W480 W1,150 W920 W1,200 W960 W
10 A1,200 W960 W2,300 W1,840 W2,400 W1,920 W
15 A1,800 W1,440 W3,450 W2,760 W3,600 W2,880 W
20 A2,400 W1,920 W4,600 W3,680 W4,800 W3,840 W
30 A3,600 W2,880 W6,900 W5,520 W7,200 W5,760 W
50 A6,000 W4,800 W11,500 W9,200 W12,000 W9,600 W

Power Factor Reference by Load Type

Choosing the correct power factor is essential for accurate wattage calculations. Here are typical power factor values for common load types. For the most accurate results, check the appliance nameplate or manufacturer specifications.

Load TypeTypical PFPhase Angle φExamplesNotes
Resistive1.00°Heaters, ovens, incandescent bulbs, kettlesAll apparent power = real power
LED Lighting0.90–0.9518°–26°LED bulbs, LED stripsBetter than older fluorescents
SMPS/Electronics0.85–0.9518°–32°Laptops, phone chargers, TVsSwitch-mode power supplies
Air Conditioners0.85–0.9223°–32°Split AC, window AC, inverter ACInverter ACs have higher PF
Refrigerators0.80–0.8828°–37°Household fridges, commercial coolersCompressor motor dominant
Electric Motors0.75–0.8828°–41°Pumps, fans, compressors, conveyorsHeavily loaded motors = higher PF
Fluorescent Lights0.50–0.6549°–60°Old tube lights, magnetic ballastsElectronic ballasts improve to 0.9+
Welding Equipment0.35–0.6053°–70°Arc welders, MIG weldersVery low PF — needs correction

Why Our AC Wattage Calculator Beats the Competition

We analyzed the top AC wattage calculators on Google. Most only calculate real power and stop there. Here's what makes our tool uniquely comprehensive:

FeatureTryGetInfoOmniCalculatorCalcToolElectronicsGB
Real Power (W)✅✅✅✅
Apparent Power (VA)✅PartialPartial❌
Reactive Power (VAR)✅Partial❌❌
Power Triangle Visual✅ Canvas❌❌❌
Single + Three Phase✅✅✅❌
Power Factor Presets✅ 6 typesPartial❌❌
Voltage Presets✅ 5 presets❌❌❌
Appliance Reference Table✅ 16 rows❌❌❌
PF Reference Table✅ 8 load typesBrief text❌❌
Wattage Conversion Table✅❌❌❌
Phase Angle (degrees)✅❌❌❌
Unit Dropdowns (mV–kV, mA–kA)✅✅❌❌
10 FAQs with Schema✅ FAQPageArticle onlyArticle only❌
Mobile Optimized✅Partial❌Partial

Single-Phase vs Three-Phase: Which One to Use?

Use Single-Phase AC when:

  • You are calculating wattage for household appliances (120V in North America, 230V in India/UK/Europe)
  • The supply is from a standard wall outlet or domestic distribution board
  • The load is a single appliance: AC unit, refrigerator, TV, heater, etc.
  • Working with single-phase inverters, UPS, or solar systems

Use Three-Phase AC when:

  • You are calculating wattage for industrial motors, heavy machinery, or large HVAC systems
  • The supply is a three-phase distribution panel (common voltages: 415V in India, 480V in North America, 400V in Europe)
  • Working with three-phase transformers, generators, or switchgear
  • Calculating power for commercial buildings with three-phase supplies

The rule of thumb: if your supply has 3 hot wires (L1, L2, L3) plus neutral and earth, it's three-phase. If it has 1 hot wire (or live) plus neutral and earth, it's single-phase. You can also check your distribution board — single-phase breakers are narrow (1-pole), while three-phase circuits use wide 3-pole breakers.

For more related calculations, use our Amps to Watts Calculator, Watts to Amps Calculator, Amps to VA Calculator, or our Transformer Calculator for step-up/step-down conversions.

Frequently Asked Questions

For single-phase AC: P = V × I × PF, where P is real power in watts, V is RMS voltage in volts, I is RMS current in amps, and PF is the power factor (0–1). For three-phase AC: P = √3 × V_LL × I × PF, where V_LL is the line-to-line voltage. The power factor accounts for the phase angle between voltage and current waveforms in AC circuits — something that does not apply in DC circuits.
Real power (W) is the actual power consumed and converted to useful work (heat, light, motion). Apparent power (VA) is the total power drawn from the supply — real plus reactive. Reactive power (VAR) is power stored and released by inductors and capacitors — it does no useful work but increases current draw. The relationship is: Apparent Power² = Real Power² + Reactive Power², forming the "power triangle". Power factor = Real Power ÷ Apparent Power.
Power factor (PF) is the ratio of real power to apparent power: PF = W / VA. It ranges from 0 to 1 and represents how efficiently electrical power is being used. A PF of 1.0 (unity) means all power is used for useful work (resistive loads like heaters and incandescent bulbs). A PF below 1 means some current flows without doing useful work — motors, transformers, and fluorescent lights are common inductive loads with PF < 1. Low power factor increases electricity bills and requires larger wiring and transformers.
Multiply voltage × current × power factor for single-phase AC: Watts = Volts × Amps × PF. Example: 120V × 10A × 0.8 PF = 960W. For three-phase: Watts = 1.732 × V_LL × Amps × PF. If you don't know the power factor, use 0.8 for motors, 0.9 for electronics, and 1.0 for purely resistive loads (heaters, incandescent bulbs). Our AC wattage calculator handles both single-phase and three-phase automatically.
Single-phase AC uses two conductors (live and neutral) and delivers power in a single alternating wave. It's standard for homes and small businesses (120V/240V in North America, 230V in Europe). Three-phase AC uses three conductors offset 120° apart, delivering constant power without pulsation. It's used in industrial settings and for large motors because it provides ~73% more power with the same conductor size. Three-phase voltages are typically 208V, 415V, or 480V line-to-line.
A 1-ton air conditioner (12,000 BTU/hr) typically uses 1,000–1,400 watts (1–1.4 kW) of electricity. A 1.5-ton AC uses approximately 1,500–2,100W, a 2-ton uses 2,000–2,800W, and a 3-ton uses 3,000–4,200W. EER (Energy Efficiency Ratio) and SEER ratings affect actual consumption — higher rated units use less power. In India, a 1.5-ton 5-star split AC typically draws about 1,200–1,500W.
Three-phase real power formula: P = √3 × V_LL × I_L × PF, where √3 ≈ 1.732, V_LL is line-to-line voltage, I_L is line current, and PF is the power factor. Alternatively using phase values: P = 3 × V_phase × I_phase × PF. The √3 factor accounts for the vector relationship between the three voltage phases offset by 120°. For three-phase apparent power: S = √3 × V_LL × I_L (in VA).
kVA (kilovolt-amperes) is apparent power — the total power delivered by the supply. kW (kilowatts) is real power — the power actually consumed as useful work. The ratio between them is the power factor: kW = kVA × PF. For a 10 kVA generator with PF = 0.8, it can deliver only 10 × 0.8 = 8 kW of real power. UPS systems and generators are often rated in kVA because they must deliver the total apparent power, not just the real component.
When power factor is below 1, the actual current flowing in the wires is higher than what would be needed if all power were real. This excess current causes additional I²R losses in wiring (where I is actual current and R is wire resistance). A motor drawing 10 kW at PF = 0.8 requires 10/0.8 = 12.5 kVA of apparent power, flowing 25% more current than if PF were 1.0. This extra current heats wires without contributing to useful power output.
Yes. Enter the voltage (120V or 240V for North America; 230V for Europe/India), the current drawn by the appliance (from its label or specifications), and the appropriate power factor. For heaters, incandescent bulbs, and ovens, use PF = 1.0. For motors, fans, and air conditioners, use PF = 0.8–0.9. For LED lighting and electronics, use PF = 0.9–0.95. The nameplate on appliances often shows watts directly — use our calculator when you only have voltage and current ratings.

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