Electricity Cost Calculator
Find what an appliance costs to run per day, month and year from its watts or amps and volts, hours of use, standby draw and your price per kWh.
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About this toolWhat is the Electricity Cost Calculator?
Your bill charges for kilowatt-hours, and every appliance turns into kilowatt-hours the same way: power in kilowatts times hours of use. A 1,500 watt space heater running four hours a day uses 6 kWh a day, which is about 2,190 kWh over a year of daily use. At 17 cents a kWh that is over 370 a year for one heater. This electricity cost calculator does that arithmetic per day, month and year for anything you plug in.
Start from a typical appliance in the list or type the wattage from the label. If the label lists amps and volts instead, switch the input and the calculator multiplies them. Add hours of use per day, days per week, the number of identical devices and the standby power drawn when they are switched off but still plugged in.
Enter the price per kWh from your bill in any currency. A table below the result runs the same price across common household appliances at typical use, which is a quick way to see where the money actually goes.
- Watts or amps x volts input, with quantity and standby draw
- Cost and kWh per hour, day, month and year
- Days-per-week setting for weekday or weekend use
- Typical appliance presets labelled as typical, with a comparison table at your price
- Any currency symbol; copy and share results
How to use the Electricity Cost Calculator
- Pick an appliance to start from, or choose Custom and enter the running watts from the label or a meter.
- If the label shows amps and volts, switch to amps x volts and enter both.
- Enter hours used per day, days per week and how many identical devices you run.
- Add standby watts if it stays plugged in, and enter your price per kWh and currency.
- Read the cost per day, month and year, and compare against the typical appliances table.
Worked examples
Space heater, four hours a day
Input
1,500 W, 4 h/day, 7 days, 0.17 per kWh
Output
6 kWh and 1.02 per day; 182.5 kWh and 31.03 per month; 2,190 kWh and 372.30 per year
This is the default example. Running it every day all year is an upper bound; a heating season of five months is closer to 155.
Office desktop on weekdays
Input
200 W, 8 h/day, 5 days a week, 3 W standby, 0.17 per kWh
Output
1.65 kWh on a working day; 430 kWh and 73.04 per year, of which 12.5 kWh is standby
Weekday-only use cuts the year to 261 days. Standby is small here but matters across many devices.
Charging an electric car at home
Input
7,200 W Level 2 charger, 2 h/day, 0.12 per kWh
Output
14.4 kWh per day; 5,256 kWh and 630.72 per year
At about 3.5 miles per kWh that is roughly 50 miles a day. An off-peak rate lowers the cost directly.
Swapping a bulb
Input
60 W incandescent vs 10 W LED, 5 h/day, 0.17 per kWh
Output
18.62 vs 3.10 per year
Six times less energy for the same light. Over a house with 20 bulbs the gap is about 300 a year.
Background and insight
A watt is a rate of energy use; a kilowatt-hour is 1,000 watts used for one hour. Energy = watts x hours / 1,000, and cost = kWh x price. Standby power is the small draw from chargers, set-top boxes and appliances with clocks or remote controls; at a few watts around the clock it adds up to tens of kWh a year per device.
Nameplate wattage is the most an appliance draws. Thermostat-controlled devices such as fridges, freezers, heaters and air conditioners cycle on and off, so their average draw over a day is much lower than the label. For those, measure with a plug-in energy meter or use the yearly kWh on an EnergyGuide label, and enter the average watts. Amps times volts gives apparent power; for motors and compressors the real power in watts can be noticeably lower.
Many bills add fixed daily charges, taxes and tiered or time-of-use rates. Use the energy charge per kWh for the period when the appliance runs; the fixed charges do not change with use.
Common use cases
Understanding a high bill
Price the big loads (heaters, dryers, AC, EV charging) to see which one moved the bill.
Comparing appliances before buying
Compare the yearly running cost of two models with different wattages to see if the efficient one pays back.
Home office and crypto rigs
Work out the electricity cost of a PC, server or workshop machine running long hours.
Landlords and shared houses
Split the cost of a shared appliance fairly by measured use.
Tips and limitations
- Use a plug-in watt meter for a week to get real average draw, especially for fridges, freezers and dehumidifiers.
- Time-of-use tariffs make when you run something as important as how long. Run the calculation with the peak and off-peak rates.
- A device that heats (kettle, dryer, heater, oven) draws the most power. Small electronics rarely matter except in large numbers.
- Unplugging standby devices saves real money only when there are many of them or they draw more than a few watts.
- Bill rates are often quoted in cents; enter 17 cents as 0.17.
Frequently asked questions
How do I calculate the cost of running an appliance?
Multiply watts by hours used and divide by 1,000 to get kWh, then multiply by your price per kWh. A 100 W device used 5 hours a day uses 0.5 kWh a day, which costs 0.085 a day at 0.17 per kWh.
How much does it cost to run a 1,500 watt heater?
It uses 1.5 kWh every hour it runs. At 0.17 per kWh that is about 0.26 an hour, 1.02 for four hours, and around 31 a month at four hours every day.
How do I convert amps to watts for the cost calculation?
Multiply amps by volts. A 10 A appliance on 120 V draws about 1,200 W; on 230 V it is about 2,300 W. For motors the true wattage can be somewhat lower than this figure.
How much electricity does a refrigerator use per month?
A modern full-size fridge typically uses 350 to 600 kWh a year, so roughly 30 to 50 kWh a month, because the compressor runs only part of the time. Check the yellow EnergyGuide label for your model.
Does standby power really cost much?
One device drawing 3 W all day uses about 26 kWh a year, a few dollars. Twenty such devices around a house add up to hundreds of kWh, which is why standby is worth a look.
Where do I find my price per kWh?
Your bill lists an energy or usage charge per kWh, sometimes split into supply and delivery. Add those per-kWh parts together and leave out fixed monthly fees.
Is there an in-depth guide to the Electricity Cost Calculator?
Yes. “Roof Pitch, Stair Layout, AC Sizing and Running Costs Explained” covers the background, how it works, common pitfalls and worked examples. Read the full guide.
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