Electricity Cost Calculator
Enter an appliance's wattage, how many hours per day you use it, and your electricity rate per kWh to see what it costs to run per day, month and year.
Electricity Cost Calculator
Calculate the cost to run an appliance
Daily kWh = watts × hours ÷ 1000. Daily cost = daily kWh × rate. Monthly = daily × 30. Yearly = daily × 365.
⚠️ Double-check important results. This is an educational estimate, not professional advice — and where it uses a rate, bracket or fee, those change over time. Verify anything you'll rely on, especially in legal, financial, tax or medical matters, and read our full disclaimer. Think a result is wrong? Tell us so we can fix it.
How Electricity Cost Is Calculated
Electricity is billed per kilowatt-hour (kWh). One kWh = 1,000 watts running for one hour.
Daily energy (kWh) = watts × hours per day ÷ 1,000 Daily cost = daily kWh × rate per kWh Monthly cost = daily cost × 30 Yearly cost = daily cost × 365
**Common wattages**: LED bulb 10W, refrigerator 150W, microwave 1,000W, space heater 1,500W, air conditioner 3,500W.
- kWh = watts × hours ÷ 1,000
- Cost = kWh × rate per kWh
- Monthly = daily × 30; yearly = daily × 365
Worked Example
Example: 1,500W space heater, 4 hours/day, $0.16/kWh.
- Daily energy = 1,500 × 4 ÷ 1,000 = 6 kWh - Daily cost = 6 × $0.16 = $0.96 - Monthly cost = $0.96 × 30 = $28.80 - Yearly cost = $0.96 × 365 = $350.40
📊 Source & data. Formula and default values reference U.S. Energy Information Administration (EIA). Last verified 2026-10-29. Rates, brackets and fees change over time — all editable fields accept your own current values.
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Open calculator →Frequently Asked Questions
Where do I find my electricity rate?
Check your utility bill — look for 'price per kWh' or 'supply charge'. Rates typically range from $0.10 to $0.40 per kWh depending on location and provider.
Do appliances use power when off?
Many draw small 'standby' or 'vampire' power (1–10W). This calculator only counts active running time; add standby separately if you want total cost.
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