Appliance Wattage Calculator

Inputs

System Type Three-phase uses √3 × V × I × PF.

Power Factor (0-1) Resistive loads ≈ 1. Motors often 0.7–0.95.

Known Value

Voltage (V)

Current (A)

Usage Hours / day

Days / month

Electricity Rate (per kWh)

Results update instantly on change.

Results

Single-phase

Electrical

Watts (W): —

Kilowatts (kW): —

Amps (A): —

Energy & Cost

kWh / day: —

kWh / month: —

Cost / day: —

Cost / month: —

Example Appliances

Appliance	Typical Watts	Hours / day	kWh / day	Cost / day
LED Bulb 9–10W	10	5	0.05	0.01
Ceiling Fan	70	8	0.56	0.14
Refrigerator	150	12	1.80	0.45
Microwave	1100	0.5	0.55	0.14
Air Conditioner 1.5 Ton	1500	5	7.50	1.88
Laptop	65	6	0.39	0.10
TV 42"	100	4	0.40	0.10

Edit watts and hours directly. Costs use the current rate above.

Formula Used

Single‑phase: P(W) = V × I × PF

Three‑phase: P(W) = √3 × V × I × PF

Energy: kWh = (P(W) ÷ 1000) × hours

Cost: Cost = kWh × rate

Power factor (PF) accounts for phase difference of voltage and current in AC systems. Resistive devices like heaters have PF≈1, motor-driven devices often have PF<1.

How to Use

Select System Type and set Power Factor (1 for purely resistive loads).
Choose whether you know Amps or Watts.
Enter Voltage and the known quantity.
Provide usage hours per day, days per month, and your electricity rate.
Press Calculate. Results show watts, amps, kWh, and costs.
Use the example table to estimate typical usage across devices; edit values inline.
Export your results as CSV or PDF for reporting.

FAQs

1) What power factor should I use?

If unknown, start with 1 for heaters and incandescent lamps. For motors or compressors, typical values range 0.7–0.95. Nameplates or manuals often include PF.

2) What is the difference between Watts and Volt‑Amperes?

Watts represent real power, while volt‑amperes represent apparent power. With PF<1, Watts = VA × PF. This tool estimates real power and energy cost.

3) Can I use this for both 120 V and 230 V regions?

Yes. Enter your local voltage. The formulas are independent of region provided the correct voltage and power factor are used.

4) How do I handle three‑phase equipment?

Select three‑phase. Provide line‑to‑line voltage and per‑phase current. The calculator applies the √3 factor automatically.

5) Do typical wattages vary?

Yes. Nameplate ratings and modes vary widely. Always prefer the device nameplate or measured values for best accuracy.

6) Does starting surge affect cost?

Starting surges raise instantaneous power briefly but have little effect on overall energy cost compared to steady‑state consumption.

7) How accurate are these estimates?

Accuracy depends on correct inputs and realistic usage assumptions. For the most precise results, measure with a plug‑in energy meter and use its readings here.

Quick Tips

Lower PF increases current for the same watts.
Reducing daily hours lowers both kWh and cost linearly.
Modern inverter ACs often consume less energy per hour than fixed‑speed units.
Standby loads add up—unplug or use smart switches.