Electricity Cost Calculator
The energy an appliance uses and what it costs per day, month and year at the price per kWh you pay.
Result…
How it's calculated
kWh per day = watts × hours a day ÷ 1000 Cost = kWh × price per kWh Per month = per day × 365 ÷ 12 · Per year = per day × 365
A kilowatt-hour (kWh) is 1000 watts running for one hour, and it is the "unit" on an electricity bill. Multiply an appliance's power by the hours it runs to get its energy, then by your price per kWh. The rated power is the most a device draws: fridges and freezers cycle on and off, and many devices use less at low settings, so a plug-in energy meter gives a truer figure. Tariffs vary by country and supplier: tiers, time-of-use prices and standing charges are not included.
Your numbers, step by step
About the Electricity Cost calculator
This electricity cost calculator shows how much energy an appliance uses and what it costs to run per day, per month and per year, at the price per kWh you enter. Give it the power in watts or kilowatts and the hours a day it runs, type the kWh a day straight from a plug-in meter, or list several appliances, one per line, to see their total and each one's share. It is useful for checking what a heater, kettle, computer or air conditioner adds to a bill, or for comparing two appliances before you buy. The steps show each multiplication with your numbers. The price is yours to enter, because tariffs differ between countries and suppliers, and the result covers the energy charge at one flat price: standing charges, taxes, tiers and time-of-use prices are not included. To find the power from volts and amps, use the electrical power calculator.
How to use it
- Under “I know”, choose “Power and hours”, “kWh per day” or “Several appliances”.
- For one appliance, enter the “Power”, pick W or kW, and enter the “Hours used per day”.
- For several, type each on its own line under “Appliances: name, watts, hours a day”, such as “Heater 2000 3”.
- Enter the number of “Days” to total and the “Price per kWh” from your bill.
- Read the cost for the period, the kWh used, and the cost per day, month and year.
Worked example
A 2000 W heater used 2 hours a day uses 2000 ÷ 1000 × 2 = 4 kWh a day. At 0.25 per kWh that is 1.00 a day, 30.00 for 30 days, about 30.42 for an average month and 365 a year. For a list of a 100 W television for 4 hours, a 60 W laptop for 8 hours, a 2000 W kettle for 0.25 hours and 40 W of lights for 6 hours, the total is 1.62 kWh a day, or 12.15 for 30 days at 0.25 per kWh.
Updated
Questions people ask
How do I calculate the cost of running an appliance?
Multiply the power in kilowatts by the hours it runs to get kWh, then multiply by your price per kWh. A 1500 W appliance for 3 hours uses 1.5 × 3 = 4.5 kWh.
What is a kWh?
A kilowatt-hour is 1000 watts used for one hour, and it is the unit on an electricity bill. A 100 W bulb takes 10 hours to use 1 kWh. The energy converter turns kWh into joules or other units.
Why is my bill higher than the calculator says?
Bills often add a daily standing or fixed charge, taxes, and prices that change by time of day or by how much you use. The calculator gives the energy charge at one flat price, so check your own tariff for the rest.
Does the watt rating show what an appliance really uses?
Not always. The rating is usually the most it draws. Fridges and freezers switch on and off, and many devices use less on low settings, so a plug-in energy meter gives a truer kWh a day to enter.
How is the monthly cost worked out?
The cost per day is multiplied by 365 ÷ 12, about 30.42 days, the length of an average month. The yearly cost uses 365 days. Use the “Days” field for an exact billing period.