Instant · Private · No sign-up
ElectricityCalculator
100% Free, Browser-Based Appliance Power Consumption & Bill Estimator.
- ⚡ Watts → kWh instantly
- 💰 Daily, monthly & yearly cost
- 🌙 Day/night tariffs
- 🏠 Household bill builder
- 🔒 100% private, client-side
Electricity usage and cost calculator
Appliance Quick-Presets
Tap to fillCheck the label on the appliance or its power adapter. Right field = number of identical units.
Household Bill Estimator
Add every appliance to build a full monthly electric bill estimate. Saved on this device only.
Monthly bill
$0.00
Yearly bill
$0.00
Monthly energy
0 kWh
Appliances
0
| Appliance | Power | Use / day | kWh / mo | Cost / mo | Share | Actions |
|---|
Household totals use the rate and tariff currently set in the calculator, so you can compare suppliers by changing the rate.
What is ElectricityCalculator?
ElectricityCalculator is a free online electricity usage calculator and electric bill estimator. Enter an appliance's wattage, how long it runs each day and your price per kWh, and it instantly shows the energy used and what it costs per hour, day, month and year. Everything runs 100% client-side in your browser — no account, no uploads, no server.
Precise power math
Watts or kilowatts, hours and minutes, quantity — recalculated live on every keystroke.
Any currency & tariff
$, €, £ or a custom symbol, with single-rate or day/night split pricing.
Household bill estimate
Add multiple appliances to see your total monthly kWh, bill and each device's share.
Copy & export
Copy a text summary or download the bill breakdown as CSV or TXT.
How to Calculate Electricity Usage & Cost
Every appliance draws a certain amount of power, measured in watts (W). Your utility bills you for energy, measured in kilowatt-hours (kWh) — the power used multiplied by the time it runs. Two simple formulas cover almost everything:
1. Watts to kWh
kWh = (W × hours) ÷ 1000
A 100 W LED TV on for 5 hours uses 0.5 kWh per day, or 15 kWh per month.
2. kWh to cost
Cost = kWh × rate per kWh
15 kWh × $0.15 = $2.25 per month to run that TV.
Typical appliance power consumption
| Appliance | Typical watts | Typical use | kWh / month |
|---|
Figures are typical estimates. Actual consumption varies by model, settings and climate.
Single rate vs day/night tariffs
Many suppliers offer a dual or time-of-use tariff, charging less for electricity used at night. Switch the calculator to Day / Night, enter both rates, and set what share of the appliance's runtime happens off-peak. Heavy loads such as electric boilers, EV chargers, washing machines and dishwashers are often cheaper when shifted to night hours.
Tips to lower your electric bill
- Target the biggest lines in your Household list first — heating, cooling and water heating usually dominate.
- Lower thermostat or AC set-points by 1–2 °C; each degree can cut heating or cooling energy noticeably.
- Kill standby power with smart plugs or switchable power strips for TVs, consoles and PCs.
- Swap remaining incandescent or halogen bulbs for LEDs, which use up to 80–90% less power.
- Run timers for boilers and heavy appliances during off-peak tariff hours.
Frequently Asked Questions
How to calculate appliance power cost per hour?
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Divide the appliance wattage by 1,000 to get kilowatts, then multiply by your electricity rate per kWh. Cost per hour = (Watts ÷ 1000) × rate. For example, a 1,500 W heater at $0.15/kWh costs 1.5 × 0.15 = $0.225 per hour.
How to convert Watts to kWh?
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Multiply the power in watts by the hours of use and divide by 1,000. kWh = (W × hours) ÷ 1000. A 100 W TV used for 5 hours uses (100 × 5) ÷ 1000 = 0.5 kWh.
How much does it cost to run a space heater daily?
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A typical 1,500 W space heater running 5 hours a day uses 7.5 kWh. At $0.15/kWh that is about $1.13 per day, roughly $34 per month. Multiply 1.5 kW × hours × your rate for your own figure — or tap the Space Heater preset above.
How much electricity does an AC use?
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A 1,500 W room air conditioner running 8 hours a day uses about 12 kWh per day or 360 kWh per month at full load. Real usage is often lower because the compressor cycles on and off once the room reaches the set temperature; inverter models are especially efficient at partial load.
How does a day/night split tariff change the cost?
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With a dual tariff, energy used during off-peak (night) hours is billed at a lower rate. The calculator splits each appliance's daily kWh by the night-usage percentage you set and applies the day and night rates separately.
Is my data sent to a server?
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No. ElectricityCalculator runs 100% in your browser. All calculations happen locally and your appliance list is only stored on your own device.