What does it cost to run per kWh?
Enter the appliance's power in watts, how many hours a day it runs, and your price per kWh. See the energy it uses and what it costs a day, a month and a year.
- Cost per month
- $25.06
Using 4.5 kWh a day costs $25.06 a month.
- Cost per day
- $0.82
- Cost per year
- $300.74
- Energy per day
- 4.5 kWh
- Energy per year
- 1,642.5 kWh
Cost per month: $25.06. Using 4.5 kWh a day costs $25.06 a month.
How to calculate
Computes the electricity an appliance uses in kilowatt-hours from its power and hours of use a day, and what that costs per day, month and year at a price per kWh.
Example with the default inputs (Power 1,500 W, Hours a day 3, How many 1, Price (¢/kWh) 18.31): Using 4.5 kWh a day costs $25.06 a month.
Method: kWh a day = power (kW) × hours a day × how many; cost a day = kWh × price; a month = 365 ÷ 12 days; a year = 365 days
- The power is the average the appliance draws while on. Appliances that cycle, such as refrigerators, draw less on average than their label.
- The price is a flat rate per kWh. Bills with tiers, time-of-use rates, fixed charges or taxes cost more or less.
- The default price is the US average residential price for July 2026, 18.31¢ per kWh, from the EIA.
Worked examples
Each example is checked against the calculator on every build.
- Power 1,500 W, Hours a day 3, How many 1, Price (¢/kWh) 18.31 gives Energy per day 4.5 kWh, Cost per day $0.82, Cost per month $25.06, Cost per year $300.74.Source: hand calculation in content.mdx: 1.5 kW × 3 h = 4.5 kWh × $0.1831 = $0.824 a day; × 30.42 = $25.06 a month; × 365 = $300.74 a year
- Power 10 W, Hours a day 5, How many 8, Price (¢/kWh) 15 gives Energy per day 0.4 kWh, Cost per year $21.90.Source: hand calculation in content.mdx: 8 × 10 W × 5 h = 400 Wh = 0.4 kWh; × 365 = 146 kWh × $0.15 = $21.90 a year
- Power 200 W, Hours a day 24, How many 1, Price (¢/kWh) 20 gives Energy per year 1,752 kWh, Cost per year $350.40.Source: hand calculation in content.mdx: 0.2 kW × 24 h = 4.8 kWh a day; × 365 = 1,752 kWh × $0.20 = $350.40
How it works
- Energy per day (kWh) = power (kW) × hours a day × how many. Power in watts is divided by 1,000 to get kW.
- Cost per day = energy per day × price per kWh. The price is in cents, so divide by 100 for dollars.
- Cost per month = cost per day × 365 ÷ 12 (an average month of 30.42 days).
- Cost per year = cost per day × 365. Energy per year = energy per day × 365.
The starting price is the EIA's US average residential price for July 2026: 18.31¢ per kWh. Type the price from your own bill for a better answer.
The power is the average draw while the appliance is on. The price is a flat rate, with no fixed charges or tiers.
Worked examples by hand
A 1,500 W space heater, 3 hours a day, at 18.31¢. 1.5 kW × 3 h = 4.5 kWh a day. 4.5 × $0.1831 = $0.824 a day. × 365 ÷ 12 = $25.06 a month. × 365 = $300.74 a year.
Eight 10 W LED bulbs, 5 hours a day, at 15¢. 8 × 10 W × 5 h = 400 Wh = 0.4 kWh a day, or 146 kWh a year. 146 × $0.15 = $21.90 a year.
A refrigerator averaging 200 W, all day, at 20¢. 0.2 kW × 24 h = 4.8 kWh a day. × 365 = 1,752 kWh a year. 1,752 × $0.20 = $350.40 a year.
Other questions people ask
How do I calculate the cost of running an appliance?
Multiply the power in kilowatts by the hours of use to get kilowatt-hours (kWh), then multiply by your price per kWh. A 1,500 W heater used 3 hours a day uses 1.5 × 3 = 4.5 kWh; at 18.31¢ per kWh that is $0.82 a day, or about $25 a month.
How do I convert watts to kWh?
kWh = watts × hours ÷ 1,000. A 100 W bulb on for 10 hours uses 100 × 10 ÷ 1,000 = 1 kWh.
What is the average price of electricity?
The U.S. Energy Information Administration reports a US average residential price of 18.31¢ per kWh for July 2026, the default here. Prices differ a lot by state and by utility, so use the price on your own bill: divide the energy charge by the kWh used.
Where do I find an appliance’s wattage?
On the label or nameplate, often on the back or bottom, or in the manual. If the label only gives amps, multiply by the voltage (120 V in most US homes) for an estimate of the watts. A plug-in energy meter measures the real use.
Why is my refrigerator’s cost lower than the label suggests?
A refrigerator’s compressor cycles on and off, so over a day it draws less than its rated power. Enter its average power, or use the yearly kWh on its EnergyGuide label with 24 hours a day.
Why does my bill not match?
Bills add fixed monthly charges, taxes and delivery fees, and many utilities use tiered or time-of-use prices. The calculator uses one flat price per kWh.