Work out kWh and the cost per day, month and year for any appliance, with optional standby power. Runs on your device.
The cost of running an appliance is its energy in kilowatt-hours (kWh) times your price per kWh. Energy per day is watts ÷ 1,000 × hours used. A 1,500 W heater used 3 hours a day uses 1,500 ÷ 1,000 × 3 = 4.5 kWh a day. Over 30 days that is 135 kWh, and over 12 months 1,620 kWh. At a price of 0.20 per kWh the cost is 0.90 a day, 27.00 a month and 324.00 a year. The page shows no currency symbol because it does not know your currency or your tariff: type the rate as it appears on your bill.
Many devices draw a little power even when they are not in use. If you type a standby figure in watts, the page counts it for the hours the appliance is not in use, which is 24 minus the hours used. With 10 W of standby, the heater above adds 10 ÷ 1,000 × 21 = 0.21 kWh a day, so the day total is 4.71 kWh, the month is 141.3 kWh and the cost at 0.20 is 28.26 a month, or 339.12 a year. If the appliance runs 24 hours a day, no standby hours are left, so none are added. Leave the box empty to ignore standby.
Use the watts on the appliance's label or manual, or better, an average read from a plug-in energy meter. A label gives the power at full output. A heater with a thermostat, a fridge or a washing machine uses that power only part of the time, so the label figure can overstate its real use. Kilowatts are 1,000 watts, so 1.5 kW and 1,500 W give the same answer. If a meter shows the energy used over a week, divide the kWh by 7 to get kWh a day, or enter its average watts instead. Hours per day may be a fraction: 30 minutes is 0.5. Days per month can be up to 31, and the year is worked out as 12 months of that pattern.
A real bill may add a daily fixed charge, different prices by time of day or by amount used, taxes and fees. This calculator multiplies kWh by one flat price, so it shows the energy part only. It also does not add the cost of any heat or cooling that an appliance changes elsewhere in the home. It is an estimate, not financial advice, and it does not list typical wattages for appliances, because they vary widely by model: read the label on yours.
Multiply watts ÷ 1,000 by the hours used for kWh, then by the price per kWh. For 1,500 W, 3 hours a day, 30 days at 0.20 per kWh: 4.5 kWh a day, 135 kWh a month, 27.00 a month.
kWh = watts ÷ 1,000 × hours. A 60 W lamp on for 5 hours uses 60 ÷ 1,000 × 5 = 0.3 kWh. Over 30 days that is 9 kWh. A 100 W device left on 24 hours uses 2.4 kWh a day.
Standby kWh = standby watts ÷ 1,000 × the hours not in use. 10 W for 21 hours a day is 0.21 kWh a day, 6.3 kWh over 30 days, and 1.26 a month at 0.20 per kWh.
The page multiplies kWh by one flat price. A bill may add a fixed daily charge, tiered or time-of-day prices and taxes. And an appliance such as a 1,500 W heater with a thermostat may run at full power for only part of the hours.
The rate printed on your bill, in your own currency, such as 0.20 or 0.145. If your bill shows prices per unit in cents or pence, convert: 25 cents is 0.25. The page adds no currency symbol and sets no default rate.
No. The numbers stay in this tab and are not stored on your device or sent anywhere. Reloading the page puts the example back. The page only counts that a result was shown, without any of your numbers.