Appliance Wattage Calculator
Find out exactly how many watts an appliance uses. Enter the grid voltage, the current drawn and the power factor from the nameplate to get real power, apparent power and daily/monthly energy consumption.
Region / grid voltage
V
A
True power the appliance actually consumes and converts to heat or work
- 1
Apparent power
230 × 6.5 = 1,495 - 2
Real power (watts)
1,495 × 1 = 1,495
How does this calculator work?
Real power (W) = Voltage × Current × Power Factor. For heaters and bulbs, PF = 1 and watts = volts × amps. For motors and electronics, PF is typically 0.7–0.95, making real power lower than apparent power (VA). Use real power for energy cost estimates; use apparent power for sizing cables and circuit breakers.
Formula
How this is calculated
Every electrical appliance draws current from the mains at a given voltage. For purely resistive loads — heaters, incandescent bulbs, electric kettles — the calculation is simply watts = volts × amps (power factor = 1). Most modern appliances, however, have motors, switching power supplies or inductive coils that shift the phase between voltage and current. This phase shift means the grid must supply more volt-amperes (VA) than the appliance actually uses in watts; the difference is reactive power (VAR), which cycles back to the grid and does no useful work.
Power factor (PF) is the ratio of real power to apparent power and ranges from 0 to 1. A power factor of 1 means all supplied VA converts to watts. Motors typically have a PF of 0.6–0.85 at partial load, while modern switched-mode power supplies are often 0.95–0.99. Energy-efficient appliances carry a PF correction circuit. The nameplate or manual usually lists PF; if not, 0.8 is a reasonable estimate for motors, 1.0 for heaters.
The calculator reports real power (what your bill is based on, in watt-hours), apparent power (what the wiring and circuit breaker must carry), and reactive power (the "wasted" circulation). Use the daily/monthly kWh figures with your tariff rate to estimate running costs.
Frequently asked questions
Check the nameplate or rating label on the appliance body (often on the back or bottom). It typically lists rated current in amps (A) or watts (W). If only watts and voltage are listed, current = watts ÷ voltage. For accurate figures under real load, use a plug-in energy monitor or clamp meter.
Use 1.0 for purely resistive loads such as electric heaters, traditional incandescent bulbs or electric kettles. Use 0.8–0.9 for motors (refrigerator compressors, washing-machine drums, fans). Modern electronics and LED lights typically have a PF of 0.95–0.99. When in doubt, 0.8 gives a conservative (slightly high) watt estimate.
Real power (watts) is the actual energy consumed per second — it does useful work and appears on your electricity bill. Apparent power (volt-amperes) is the product of voltage and current that the grid and wiring must handle. The difference is reactive power, which flows back and forth between source and load without being consumed. Your utility bills you for kWh (real power) but sizes infrastructure for VA.
Also known as
TG we-Calculate Editorial Team. (2026). Appliance Wattage Calculator [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/appliance-wattage-calculator
TG we-Calculate Editorial Team. "Appliance Wattage Calculator." TG we-Calculate. 2026. https://we-calculate.com/calculator/appliance-wattage-calculator.
TG we-Calculate Editorial Team, "Appliance Wattage Calculator," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/appliance-wattage-calculator
@misc{wecalculate_appliance_wattage_calculator, title = {Appliance Wattage Calculator}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/appliance-wattage-calculator}}, year = {2026}, note = {TG we-Calculate} }
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