Electricity Cost Calculator
See what a device really costs to run. Enter its wattage, how long it runs, and your electricity rate to get daily, monthly, and yearly cost.
Example: with Power 1000 watts · Power unit Watts (W) · Hours per day 5 hrs · Capacity / duty cycle 100% → Cost for the period: $25.50.
- Cost per day$0.85
- Cost per year$310
- Energy per day5.00 kWh
Computed by the calculator below using its default values. Change any input to see your own numbers.
Cost: day / month / year
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Check it outReading your usage
Electricity is billed per kilowatt-hour (kWh) — 1,000 watts running for one hour. Find the wattage on the appliance label or nameplate, and your rate on your utility bill. Heaters, dryers, and AC units dominate bills because they pull thousands of watts; small electronics cost little even running all day. If your device is rated in kilowatts, BTU/hour, or tons (common for AC and heat-pump units), switch the power unit selector instead of converting by hand — and if it cycles on and off rather than running at full draw the whole time, lower the capacity / duty cycle percentage for a more realistic estimate.
How it’s calculated
kWh per day = watts × hours ÷ 1000. Cost = kWh × rate; period and annual scale by days and 365.
Power unit conversions to watts: 1 kW = 1,000 W; 1 BTU/hour = 0.2931 W; 1 ton (refrigeration) = 3,517 W. The capacity / duty cycle percentage scales the effective wattage before the kWh calculation (100% = full rated wattage, unchanged from the base formula).
Results update as you type and are estimates, not professional advice — verify important decisions with a qualified professional.
Common mistakes
- Using amps as watts (multiply amps by volts).
- Forgetting always-on standby power.
Frequently asked questions
Where do I find the wattage?
On the appliance's label or manual. If only amps are listed, multiply amps by volts (usually 120) to get watts.
What's a typical rate?
U.S. residential rates vary widely by state. Use the price per kWh printed on your latest bill for accuracy.
Does standby power count?
Yes — many devices draw a few watts even when off. For always-on devices, set hours to 24.