Electricity Cost Calculator — kWh & Bill Estimator
Calculate the electricity cost of any appliance or device. Enter the power consumption in watts, how many hours per day you use it, the number of days, and your electricity rate per kWh. Get instant daily, monthly, and annual cost breakdowns.
- Total Electricity Cost
- 36.00
- Per Day
- 1.20
- 8 kWh
- Per Month (30 days)
- 36.00
- 240 kWh
- Per Year (365 days)
- 438.00
- 2,920 kWh
240 kWh
How it works
How electricity cost is calculated
Electricity is billed in kilowatt-hours (kWh). One kilowatt-hour is the energy used by a 1000-watt appliance running for one hour. To find your kWh usage: divide the appliance wattage by 1000 to get kilowatts, then multiply by hours used. A 1500-watt space heater running 6 hours uses 1.5 kW × 6 h = 9 kWh. Multiply that by your electricity rate (say $0.15/kWh) to get the cost: 9 × $0.15 = $1.35 for that session.
Most electricity bills show a rate in cents or dollars per kWh. In the United States, the average residential rate is around $0.13–$0.17/kWh, but it varies significantly by state and utility. In Europe, rates typically range from €0.10 to €0.40/kWh. Japan averages around ¥25–35/kWh. Always check your latest bill for the exact rate — it may include tiered pricing, taxes, and distribution fees.
Common appliance power consumption
Knowing typical wattages helps you estimate costs without measuring. Space heaters: 1500 W. Central air conditioner: 3500 W. Window AC unit: 900–1500 W. Electric oven: 2000–5000 W. Microwave: 600–1200 W. Refrigerator: 100–200 W (runs ~8 hours equivalent per day). Washing machine: 500 W. Clothes dryer: 4000 W. Dishwasher: 1200 W. Desktop computer: 100–300 W. Laptop: 30–70 W. 65-inch LED TV: 80–130 W. LED bulb: 8–15 W (vs. 60 W incandescent equivalent).
The wattage printed on a device label is the maximum draw. Many appliances cycle on and off or vary power based on load — a refrigerator compressor doesn't run constantly, and a computer draws less power at idle than under load. For more accurate cost tracking, a smart plug with energy monitoring (such as TP-Link Kasa or similar) measures actual consumption rather than rated wattage.
Reducing your electricity bill
Heating and cooling account for roughly 40–50% of the typical household electricity bill in temperate climates. Upgrading to a programmable or smart thermostat can reduce HVAC costs by 10–15%. Setting the temperature 7–10°F lower for 8 hours per day (while sleeping or away) saves about 10% annually. Proper insulation and weather stripping keep conditioned air inside, reducing how often heating and cooling systems cycle on.
Switching from incandescent to LED lighting saves 75–80% on lighting energy. LED bulbs also last 15–25 times longer. Unplugging devices in standby mode eliminates 'vampire' or 'phantom' loads that account for 5–10% of household electricity use. High-efficiency appliances (Energy Star rated) use 10–50% less energy than standard models — the upfront cost is usually recovered in 2–5 years through bill savings.
Frequently asked questions
›How do I find my electricity rate?
Check your monthly electricity bill — it lists the rate in cents or dollars per kWh. In the US, look for 'energy charge' or 'consumption charge.' Many utilities also post rates on their website. Note that your effective rate may include fixed fees, tiered pricing above a threshold, and taxes — the total bill divided by total kWh gives your all-in effective rate.
›What is a kilowatt-hour (kWh)?
A kilowatt-hour is a unit of energy equal to using 1000 watts for 1 hour. It is the standard billing unit for electricity. One kWh will run: a 100-watt light bulb for 10 hours, a laptop (50 W) for 20 hours, a microwave (1000 W) for 1 hour, or a 1500-watt heater for 40 minutes.
›How much does it cost to run a TV all day?
A modern 55-inch LED TV uses about 80–130 watts. At 8 hours per day and $0.15/kWh: 100 W × 8 h = 0.8 kWh × $0.15 = $0.12/day, about $3.60/month, $43.80/year. Older plasma TVs used 300–400 W and cost 3–4 times more to run.
›How much does it cost to charge an electric vehicle?
A typical EV uses about 25–40 kWh per 100 miles (or 15–25 kWh/100 km). At $0.15/kWh and 30 kWh/100 miles, charging costs $4.50 per 100 miles. A full charge of a 75 kWh battery pack costs 75 × $0.15 = $11.25. Charging at home overnight is cheaper than public DC fast chargers.
›Why does my bill vary month to month?
Electricity bills vary with seasonal usage (heating in winter, AC in summer), changes in behavior (working from home, guests), rate changes by your utility, and tiered pricing that kicks in above a usage threshold. Many utilities charge a higher rate once you exceed a base allocation of kWh per month.
›What appliances use the most electricity?
In most homes, the biggest consumers are: HVAC (heating/cooling) at 40–50% of total usage, water heater at 15–20%, washer and dryer at 10–15%, refrigerator at 5–10%, and lighting and electronics making up the rest. Reducing HVAC usage has the highest impact on your bill.
›What is the difference between watts and kilowatts?
1 kilowatt (kW) = 1000 watts (W). Watts measure instantaneous power — how fast energy is consumed. Kilowatt-hours (kWh) measure energy over time. A 2000-watt (2 kW) oven running for 30 minutes uses 2 kW × 0.5 h = 1 kWh of energy.
›Can I use this calculator for solar panel output?
Yes. If your solar panels produce 5000 watts (5 kW) and your location gets an average of 4.5 peak sun hours per day, your daily production is 5 kW × 4.5 h = 22.5 kWh/day. Enter 5000 W, 4.5 hours/day, and your net metering rate or the retail electricity rate to calculate the value of your solar output.
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