Free electricity cost calculator. Enter wattage, hours per day, days per month and your rate to get kWh used and cost per day, month and year.
Your results will appear here.
Enter your values and press Calculate.
Enter the appliance wattage, hours used per day, days used per month, and your electricity rate per kWh. The calculator estimates energy consumption and cost for one appliance: it converts watts to kilowatts, multiplies by hours for daily kWh, scales to month and year, then multiplies by your rate for cost.
Start with watts divided by 1,000 to get kilowatts (kW). Multiply by hours per day for daily kilowatt-hours (kWh). Multiply by days per month for monthly kWh, or by 365 for yearly kWh. Multiply any kWh figure by your rate per kWh for the cost. That is the whole calculation: watts to kW, kW to kWh, kWh to cost.
Find the wattage on the appliance label, manual, or product page. Enter hours per day and days per month honestly: a heater on a thermostat does not run at full power all day (see the cycling note below). Enter your rate from your bill, then read daily, monthly, and yearly kWh and cost in one panel.
1,500 / 1,000 = 1.5 kW. Daily: 1.5 × 8 = 12 kWh, costing $1.92. Monthly: 12 × 30 = 360 kWh, costing $57.60. Yearly: 12 × 365 = 4,380 kWh, costing $700.80. The same steps work for any appliance: a 100 W bulb for 10 hours at $0.12 costs $0.12 a day and $3.60 a month.
kW is power (how fast energy is used, like speed). kWh is energy (how much is used, like distance). A 1,500 W heater uses 1.5 kW while running, but only 12 kWh if it runs 8 hours. Your electric bill charges kWh, not kW, which is why hours matter as much as wattage.
This appliance wattage chart uses $0.16 per kWh and typical use: a 1500 watt heater, a central air conditioner at 3,500 W, and a Level 2 EV charger at 7,200 W are the big loads. LED bulb 10 W, about $0.38 a month; WiFi router 12 W running 24 hours, about $1.38 a month; laptop 50 W, about $2 to $4 a month; LED TV 80 W for 5 hours, about $1.92 a month; refrigerator cycling at about 1.5 kWh a day, about $7.20 a month; washing machine about 1 kWh per cycle; microwave 1,000 W, about $0.16 an hour; space heater 1,500 W, about $1.92 per 8-hour day; central AC 3,500 W, about $4.48 per 8-hour day.
Wattage is on the rating label, in the manual, or on the product page. If you only have volts and amps, watts = volts × amps (times power factor for motors and some electronics). Your rate is the energy or usage charge on your bill, in cents or pence per kWh divided by 100. For an all-in rate, divide your total bill by kWh used, but then do not add fixed charges again.
Fridges, freezers, and thermostat heaters cycle on and off, so they do not draw nameplate watts all day: a 150 W fridge may average only 1.2 to 2 kWh a day. For those, enter the average running hours, not 24. Standby loads are the opposite trap: a constant 10 W load uses 87.6 kWh a year, about $13 at $0.15 per kWh, so switch off or use a smart strip.
Bills add fixed or standing charges, taxes, delivery charges, tiered rates, and time-of-use rates that this energy-only estimate excludes. If your rate is a tiered or time-of-use rate, the estimate will differ. Other household loads also share the bill, so one appliance never explains the whole total.
Cut hours on the highest-cost appliance first, switch to LED lighting, use smart power strips for standby loads, adjust the thermostat, run large appliances off-peak where your tariff rewards it, keep dryer filters clean, and compare tariffs when your contract ends. A 60 W bulb swapped for a 9 W LED, 4 hours a day, saves about 74.5 kWh a year, about $11 at $0.15 per kWh per bulb.
One kWh equals 3.6 megajoules or about 3,412 BTU. Solar and battery sizes are quoted in kWh, EV charging in kWh, and generator output in kW: the same kW versus kWh distinction decides whether a number is a rate or an amount.
A kilowatt-hour is 1,000 watts used for one hour. It is the unit your electricity bill charges.
kW is power, the rate of use. kWh is energy, the total used. A 1.5 kW heater running 8 hours uses 12 kWh.
Divide watts by 1,000 for kW, multiply by hours for kWh, then multiply by your rate per kWh.
Find daily kWh (kW × hours), multiply by days per month, then multiply by your rate per kWh.
It varies by country and tariff. The average electricity price per kWh in the US is often cited near $0.16 to $0.18, and the average electricity price per kWh in the UK near 26p. Check your own bill for your rate.
One kWh, so exactly your rate: $0.15 at $0.15 per kWh, $0.16 at $0.16 per kWh.
Multiply watts by 8,760 hours and divide by 1,000 for yearly kWh, then by your rate. A 12 W router costs about $17 a year at $0.16 per kWh.
Heating, cooling, and water heating usually dominate, followed by laundry, cooking, and entertainment. A single space heater can out-cost a whole shelf of small electronics.
Roughly 25 to 30 kWh per day for a US home, but small efficient homes use far less. This calculator totals one appliance; add appliances for a whole-home figure.
Cut hours on the biggest loads, switch to LED, kill standby loads with smart strips, use off-peak hours where rewarded, and compare tariffs.
On your bill as the energy or usage charge per kWh. If it is quoted in cents, divide by 100 to get dollars per kWh.
It is plugged in all day but cycles on and off, so it draws power only part of the time. Use average running hours, not 24, or about 1.2 to 2 kWh a day for a typical fridge.
Standby is the power devices draw when off but plugged in. One 10 W standby load costs about $13 a year at $0.15 per kWh; several add up.
For AC motors and some electronics, real power is volts × amps × power factor. For most household resistance loads (heaters, kettles, bulbs) the factor is 1, so watts = volts × amps.
Yes: watts = volts × amps (times power factor if known), then kWh = watts / 1,000 × hours.
Bills add fixed charges, taxes, delivery fees, tiered or time-of-use rates, and every other load in the home. This tool estimates energy cost for one appliance only.
No. Enter an all-in rate (total bill divided by kWh) if you want taxes and fixed charges reflected, but then do not add them again.
Run each appliance separately and add the kWh and costs. Shared fixed charges stay separate.
At $0.17 per kWh, $51.00. At 26p per kWh, about 78 pounds. Multiply your kWh by your own rate for your figure.