Electricity Cost Calculator
Estimates the running cost of an appliance from its power in watts, hours of use and your electricity tariff in cost per kWh.
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How to use this calculator
- Enter the appliance's power in watts, how many hours a day it runs, and your electricity rate in $/kWh.
- Press Calculate to see the running cost per day, week, month and year.
How it works
Energy in kWh per day = power (watts) ÷ 1000 × hours. The cost is that energy times your rate, then scaled to week (×7), month (×30.44) and year (×365.25).
Worked example
A 1000 W heater, 5 h/day at $0.30/kWh. 5 kWh/day = $1.50/day ≈ $10.50/week, ≈ $547/year.
Common mistakes
- Using watts where the figure is kilowatts (or vice versa) — a 2 kW heater is 2000 W.
- Forgetting the daily supply charge — this tool counts usage only, not fixed daily fees.
- Assuming the appliance draws full power the whole time — many cycle on and off (e.g. fridges, thermostats).
Frequently asked questions
Where do I find the power in watts?
On the appliance's rating label or manual. For something rated in amps, watts ≈ volts × amps (e.g. 240 V × 4 A = 960 W).
What rate should I use?
Your usage (per-kWh) rate from your electricity bill. Many bills also have a daily supply charge that this tool doesn't include.
Related tools
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- Battery Life Calculator
- Watts to kWh Calculator
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- Watts to Amps Calculator
- Energy Cost Calculator
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Cite this tool
Zerdly. (2026). Electricity Cost Calculator. Retrieved from https://www.zerdly.com/tools/electricity-cost-calculator/
Tip: Enter any known values to calculate the remaining results.
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