How this electricity cost calculator works
Your electricity bill is based on energy, measured in kilowatt-hours (kWh). One kilowatt-hour is the energy a 1,000-watt appliance uses in one hour. To find what something costs to run, you only need three things: how much power it draws, how long you use it, and the price you pay per kWh.
The calculation has two simple steps. First convert the appliance's power to kilowatts by dividing watts by 1,000. Then multiply kilowatts by the hours of use to get energy in kWh, and multiply that by your rate. We scale a typical day up to a week using your days-per-week figure, and approximate a month as 52 ÷ 12 weeks so the monthly and yearly totals stay consistent.
Typical appliances and yearly running cost
Estimates at $0.16/kWh and typical use. Your real cost depends on the exact wattage, how long you run it, and your local rate.
| Appliance | Power | Typical use | Approx. yearly cost |
|---|---|---|---|
| LED light bulb | 10 W | 5 h/day | $3 |
| Laptop | 50 W | 8 h/day | $23 |
| Refrigerator | 150 W | 24 h/day* | $210 |
| Desktop PC | 200 W | 6 h/day | $70 |
| Window AC unit | 1,200 W | 8 h/day | $560 |
| Space heater | 1,500 W | 5 h/day | $438 |
| Electric kettle | 2,000 W | 0.2 h/day | $23 |
*A fridge cycles its compressor on and off, so it does not draw its full rated power continuously; the figure shown is a typical effective estimate.
Frequently asked questions
- How much does it cost to run an appliance?
- Multiply the appliance's power in kilowatts by the hours you use it to get kilowatt-hours, then multiply by your rate. A 1,000 W appliance used 3 hours a day at $0.16/kWh costs about $0.48 a day, roughly $175 a year.
- How do I calculate electricity cost from watts?
- Divide watts by 1,000 to get kilowatts, multiply by hours used for kilowatt-hours, then multiply by your price per kWh. So 1,500 W is 1.5 kW; run 2 hours it uses 3 kWh, which at $0.16/kWh costs $0.48.
- How many kWh does a 1000W device use?
- A 1,000-watt device is 1 kilowatt, so it uses 1 kWh per hour of running. Over 3 hours that's 3 kWh; over a full day it would be 24 kWh.
- How much does it cost to run a space heater or AC?
- A 1,500 W space heater run 5 hours a day at $0.16/kWh costs about $1.20 a day, roughly $438 a year. A 1,200 W window AC run 8 hours a day costs about $1.54 a day, near $560 a year.
- What is a kilowatt-hour (kWh)?
- It's the energy used by a 1,000-watt appliance running for one hour — the unit your utility bills you in. Cost equals kWh used multiplied by your rate per kWh.
- How can I lower my electricity bill?
- Target the biggest, longest-running loads: heating, cooling, water heating and old appliances. Run them fewer hours, switch to efficient models, cut standby drain, and shift use to off-peak times if your tariff varies.