Electricity cost calculator
Cost = watts × hours ÷ 1,000 × price per kWh. A 1,000 W heater running 4 hours a day uses 4 kWh a day. Enter the watts, the hours and your rate to get the cost per day, month and year.
Your bill's total ÷ kWh used. 0.18 is the US residential average.
- Per day
- $0.72
- Per year
- $263
- Energy per day
- 4 kWh
- Energy per month
- 121.7 kWh
How it is calculated
- kWh per day = 1,000 W × 4 h ÷ 1,000 = 4
- Per month = 4 kWh × 30.4 days × $0.18 = $22
How to calculate electricity cost
The cost is the energy used, in kilowatt-hours, times the price of one kWh. The worked numbers use the calculator's defaults: 1,000 W for 4 hours a day at $0.18 per kWh, the US residential average for August 2026.
Step 1: energy per day
kWh per day = watts × hours a day ÷ 1,000
Example 1,000 W × 4 h ÷ 1,000 = 4 kWh
Step 2: cost per day
Cost per day = kWh per day × price per kWh
Example 4 kWh × $0.18 = $0.72
Step 3: cost per month and per year
Cost per month = cost per day × 30.42 (365 days ÷ 12)
Cost per year = cost per day × 365
Example $0.72 × 30.42 = $22 a month; $0.72 × 365 = $263 a year
Cost to run an appliance per month
At $0.18 per kWh, the US residential average for August 2026, a 1,000 W load running 4 hours a day costs $22 a month and running all day costs $131. Your own rate is on your bill; the cost scales with it.
| Watts | 1 h a day | 4 h a day | 8 h a day | 24 h a day |
|---|---|---|---|---|
| 100 | $0.55 | $2.19 | $4.38 | $13 |
| 250 | $1.37 | $5.47 | $11 | $33 |
| 500 | $2.74 | $11 | $22 | $66 |
| 1,000 | $5.47 | $22 | $44 | $131 |
| 1,500 | $8.21 | $33 | $66 | $197 |
| 3,000 | $16 | $66 | $131 | $394 |
| 5,000 | $27 | $110 | $219 | $657 |
- 1 h a day
- 4 h a day
- 8 h a day
- 24 h a day
What do appliances cost to run per year?
A refrigerator that uses 305–799 kWh a year costs $55–$144 a year at $0.18 per kWh. For appliances that cycle on and off, the yearly energy use published for them gives a better cost than watts × hours. The table lists every appliance whose yearly kWh is published in the documents listed under Sources; each name links to the appliance's own page.
| Appliance | kWh per year | Cost per year | Cost per month |
|---|---|---|---|
| Dishwasher | 200–275 | $36–$50 | $3.00–$4.13 |
| Mini Fridge | 106–329 | $19–$59 | $1.59–$4.93 |
| Electric Dryer | 608–687 | $109–$124 | $9–$10 |
| Refrigerator | 305–799 | $55–$144 | $5–$12 |
| House | 10,356–10,791 | $1,864–$1,942 | $155–$162 |
Where to find the numbers
Watts are on the nameplate or in the manual. Devices that cycle, such as refrigerators and air conditioners, draw full power only part of the time; their yearly kWh figure, when the label gives one, is more accurate than watts × hours.
Your price per kWh is on your electricity bill: divide the energy charge by the kWh used. The default rate is the US residential average.
Why your bill can differ
The default price of $0.18 per kWh is the US residential average for August 2026. Prices differ by state and by utility, and some plans charge a different price by time of day or above a monthly amount of energy. On such a plan, enter the price for the hours the appliance actually runs.
The calculator counts the energy the appliance uses and nothing else. A bill may also carry fixed monthly charges and taxes that do not depend on kWh, so the whole bill divided by the kWh gives a higher price than the energy rate alone.
Hours of use are the largest unknown. Thermostats, compressors and power-saving modes run a device below its rated watts for part of the time, and many devices draw a little power when switched off. A plug-in energy meter, or the yearly kWh on the label, measures the actual use.