💡 Electricity Cost Calculator
Find out how much electricity any appliance uses and what it costs to run per day, month and year.
Quick answer: kWh = watts × hours ÷ 1,000, and cost = kWh × price. A 100 W TV used 5 hours a day uses 0.5 kWh daily – 15 kWh over 30 days, costing $2.55 a month at $0.17 per kWh ($30.60 a year).
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Electricity Cost Calculator inputs
Result
Cost per month
$2.55
100 W × 5 h/day × 30 days
| Per day (in use) | $0.09 · 0.5 kWh |
| Per month | $2.55 · 15 kWh |
| Per year | $30.60 · 180 kWh |
Monthly cost of common appliances at this price
| Appliance | kWh / month | Cost / month |
|---|---|---|
| LED bulb – 10 W | 1.5 | $0.26 |
| Laptop – 50 W | 7.5 | $1.28 |
| TV – 100 W | 15 | $2.55 |
| Fridge – 150 W | 22.5 | $3.83 |
| Air conditioner – 1,500 W | 225 | $38.25 |
| Space heater – 2,000 W | 300 | $51.00 |
Assumes 5 hours a day for 30 days.
How to calculate electricity cost
Appliances are rated in watts (W), but electricity is billed in kilowatt-hours (kWh) – the energy used by a 1,000 W device running for one hour. Convert usage to kWh, then multiply by your rate.
kWh = watts × hours ÷ 1,000 · Cost = kWh × price per kWh
Worked example
A 100 W television watched 5 hours a day uses 100 × 5 ÷ 1,000 = 0.5 kWh per day. Over a 30-day month that is 15 kWh; at $0.17 per kWh the cost is $2.55 a month, or $30.60 a year.
Typical appliance wattages
| Appliance | Typical power |
|---|---|
| LED bulb | 5–15 W |
| Laptop | 30–90 W |
| Television | 50–200 W |
| Refrigerator | 100–250 W (cycles on and off) |
| Window air conditioner | 500–1,500 W |
| Space heater | 1,500–2,000 W |
| Electric kettle | 2,000–3,000 W |
Finding an appliance's wattage
Look for a rating plate on the back or underneath, or on the power adapter. If only amps are shown, multiply by your mains voltage (120 V in North America, 230 V in most other countries). A plug-in energy monitor gives the most accurate real-world figure.
Tips to cut your bill
- Heating and cooling appliances dominate costs – lower the thermostat setting a degree or two.
- Replace old incandescent bulbs (60 W) with LEDs (about 9 W) for the same light.
- Switch off devices at the wall to eliminate standby power.
- Run washing machines and dishwashers on full loads and at off-peak times if you have a time-of-use tariff.
Running the numbers for your biggest appliances first usually shows where most of the bill goes, so you can focus your savings there.
Frequently asked questions
How do I calculate the cost of running an appliance?
Multiply the wattage by the hours used and divide by 1,000 to get kilowatt-hours, then multiply by your price per kWh. A 2,000 W heater running 3 hours uses 6 kWh – $1.02 at $0.17/kWh.
Where do I find my price per kWh?
It is printed on your electricity bill. If you pay a standing (daily) charge as well, use only the unit rate here. The US average is roughly 16–18 cents per kWh, but rates vary widely.
Why is my fridge cheaper than this estimate?
Fridges, freezers and air conditioners cycle their compressor on and off, so they rarely draw full power all day. A fridge rated at 150 W running 24 hours typically uses only a third to a half of that energy.
Do devices use power when switched off?
Many do. Standby or "vampire" power from TVs, consoles and chargers is usually 0.5–5 W each, which can add up to tens of dollars a year across a home.