Electricity Cost Calculator
Daily kWh
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Daily Cost
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Monthly Cost
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Yearly Cost
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How to Use
Enter the wattage of your appliance, the number of hours you use it per day, and your electricity rate per kWh. The calculator instantly shows your daily energy consumption in kWh and the estimated daily, monthly (30 days), and yearly (365 days) electricity costs.
Understanding Electricity Costs
Electricity is measured in kilowatt-hours (kWh). One kWh is the energy consumed by a 1,000-watt appliance running for one hour. Your electricity bill is calculated by multiplying the total kWh consumed by your rate per kWh. The formula is: Cost = (Watts x Hours) / 1000 x Rate per kWh. For example, a 100W light bulb running 10 hours a day at $0.12/kWh costs about $0.12 per day or $3.60 per month.
Calculation Formula
Daily kWh = Watts x Hours per Day / 1000. Daily Cost = Daily kWh x Rate per kWh. Monthly Cost = Daily Cost x 30 days. Yearly Cost = Daily Cost x 365 days. These are estimates based on consistent daily usage. Actual bills may vary due to tiered pricing, seasonal rates, taxes, and fees.
Common Use Cases
- Estimating the running cost of appliances like air conditioners, heaters, or refrigerators.
- Comparing energy costs between old and new appliances before purchasing.
- Calculating whether solar panels or energy-efficient upgrades are worth the investment.
- Budgeting monthly electricity expenses for a household or office.
- Understanding which devices consume the most electricity to reduce your bill.
Tips
- Check the wattage label on your appliance or its manual — it's usually listed on a sticker near the power cord.
- Many appliances don't run at full power all the time — a refrigerator cycles on and off, so estimate lower hours.
- Electricity rates vary by region and time of day — check your latest bill for your actual rate.
- LED bulbs use about 10W compared to 60W for incandescent bulbs — a simple swap saves significant money yearly.
- Standby power ('phantom load') from devices like TVs and chargers can add 5-10% to your bill.
Privacy
All calculations happen in your browser. No data is sent to any server.
FAQ
What is the difference between watts (W) and kilowatt-hours (kWh)?
Watts measure the instantaneous power a device draws, while kilowatt-hours measure the energy consumed over time. Bills are charged per kWh, so a 1,000 W device running for one hour uses 1 kWh.
Are the rate and usage values I enter sent to a server?
No. The kWh and the daily, monthly, and yearly cost calculations all happen entirely in your browser. The values you enter are never sent to a server or stored anywhere.
Will the cost shown match my actual electricity bill?
It is an estimate only. It assumes constant usage with 30 days per month and 365 days per year, so your real bill can differ due to tiered pricing, seasonal rates, fixed charges, and taxes.
How should I enter appliances that don't run continuously, like a refrigerator?
Refrigerators and air conditioners cycle on and off, so entering their rated wattage for 24 hours overestimates the cost. Estimate the hours the compressor is actually running and enter a lower usage figure for a more realistic result.
Can I calculate several appliances together?
This tool calculates one device at a time. To get a combined total, calculate each appliance separately and add up their daily, monthly, or yearly costs.