Electricity Cost Calculator
Estimate energy use and electricity cost after clicking Calculate
Results
Step-by-step derivation
References
- Energy in kWh: E = (P in W ÷ 1000) × t (hours).
- Period cost: Cost = E × price per kWh.
- Annualization: multiply period cost by 365.25 (day), 52 (week), 12 (month), or 1 (year).
Use this Electricity Cost Calculator to estimate how much electricity a device uses and how much it may cost to run based on its power rating, usage time, and electricity price per kilowatt-hour.
Electricity Cost Formula
If power is entered in watts:
Power in kW = watts ÷ 1,000
Energy use is:
Energy (kWh) = power (kW) × usage time (hours)
Electricity cost is:
Cost = energy used (kWh) × price per kWh
For annual estimates, the calculator scales the selected daily, weekly, or monthly usage pattern across a year.
Example
Suppose a 1,500 W electric heater runs for 4 hours per day and electricity costs $0.16 per kWh.
Power = 1,500 ÷ 1,000 = 1.5 kW
Energy use = 1.5 × 4 = 6 kWh per day
Daily cost = 6 × $0.16 = $0.96
If the same usage continues every day:
Annual cost ≈ $0.96 × 365.25 = $350.64
Important Notes
- Use the electricity rate shown on your utility tariff or bill.
- Rated wattage may differ from actual average power use because many appliances cycle on and off or change power during operation.
- Refrigerators, air conditioners, heat pumps, computers, and similar devices may be estimated more accurately using measured or manufacturer-provided energy-use data.
- Some devices continue using electricity in standby mode.
- The calculator estimates energy cost only. Actual bills may also include fixed charges, taxes, tiered rates, time-of-use pricing, delivery charges, demand charges, or credits.
- The selected currency symbol only changes how the result is displayed; it does not perform currency conversion.