Electricity Cost Calculator
Calculate how much an appliance costs to run.
Enter watts, usage hours, and electricity rate to see daily, monthly, and yearly costs.
This calculator tells you how much it costs to run any electrical appliance — a fridge, TV, electric heater, or EV charger — based on wattage, daily usage, and your electricity rate.
kWh stands for kilowatt-hour. It’s the standard unit your power bill is measured in: how much energy a 1,000-watt appliance uses if you run it for one hour. Most utilities charge by the kWh.
The Formula
Daily kWh = (Watts × Hours per day) ÷ 1,000 Daily cost = Daily kWh × price per kWh Monthly cost = Daily cost × 30 Yearly cost = Daily cost × 365
Watts From Amps and Volts
If your appliance shows amps and volts but not watts, multiply them:
Watts = Amps × Volts
A typical North American outlet is 120 V, so a “10 amp” appliance pulls 10 × 120 = 1,200 watts. In the UK and most of Europe, outlets are 230 V, so the same 10 amps would be 2,300 watts.
Typical Appliance Wattages (Reference)
| Appliance | Watts | Notes |
|---|---|---|
| LED bulb | 10 | 85% less than old incandescent (60W) |
| Laptop | 50 | 80W during heavy use |
| Refrigerator | 150 | Always on but cycles, real use is ~30% of time |
| Gaming PC | 300 to 700 | Higher under load |
| Microwave | 1,000 | But used briefly |
| Dishwasher | 1,500 | Per cycle ~1.5 kWh |
| Toaster | 1,200 | |
| Electric kettle | 1,500 to 3,000 | Brief but high-wattage |
| Hair dryer | 1,800 | |
| Window AC unit | 1,000 to 1,500 | |
| Central AC | 3,500 | Big variable in summer power bills |
| Electric oven | 3,000 | |
| Tumble dryer | 3,000 | |
| Electric heater | 1,500 to 2,500 | |
| EV (Level 2 charger) | 7,000 | Adding ~25 miles per hour of charge |
These are approximate — check your appliance’s nameplate or manual for the exact figure.
Electricity Prices (Approximate, Vary by Region and Year)
- US average: ~$0.16/kWh (ranges $0.10 in low-cost states to $0.30+ in California/Hawaii)
- UK average: ~£0.25/kWh (price cap)
- Most of Europe: €0.15 to €0.35/kWh
These change yearly. Check your bill for the actual rate.
Worked Examples
Refrigerator (always on, but cycles ~30%): Effective: 150W × 24 × 0.3 = 1.08 kWh/day At $0.16/kWh: $0.17/day = $63/year
Electric kettle (used 6× a day for 2 min): 3,000W × 0.2 hours = 0.6 kWh/day At $0.16/kWh: $0.10/day = $35/year
Window AC (5 hours/day, 5 months/year): 1,500W × 5 × 150 days / 1,000 = 1,125 kWh per season At $0.16/kWh: $180 per season
Where to Save
- Heating and cooling are usually the biggest single line on the bill (40 to 60% in many homes)
- LED bulbs save 85% over incandescent — a typical home with 30 bulbs saves $100+/year
- Standby power (“vampire load”) from devices left plugged in: $50 to $100/year per household. Power strips with switches solve this.
- One degree lower on heating saves about 10% on the heating portion of your bill