Electricity Cost Calculator
Your estimate
- Cost per year
- $389
- Cost per day
- $1.08
- Energy per month
- 180 kWh
- Energy per year
- 2,160 kWh
What a heater, AC, TV, fridge or PC costs to run — per day, month and year.
Updated 2026-10-20 · Based on: Ohm’s law, NEC Chapter 9 Table 8, 210.20 and 310.16; DIN VDE 0100-520 for metric.
How to use the Electricity Cost Calculator
- Enter the power in watts from the label (or measure it with a plug-in meter).
- Enter how many hours a day it runs and on how many days a month.
- Enter your electricity rate per kWh from your bill (the US average is about 18 ¢).
- Read the cost per month and year and the kWh used.
Formula
kWh per day = watts × hours ÷ 1,000 (× the number of devices).
Cost = kWh × rate. Per month = daily kWh × days used; per year = 12 months.
Worked example
With the values preset in the calculator above:
- Power
- 1,500 W
- Hours per day
- 4 hours per day
- Days per month
- 30 days per month
- Number of devices
- 1
- Cost per month
- $32.40
- Cost per year
- $389
- Cost per day
- $1.08
- Energy per month
- 180 kWh
- Energy per year
- 2,160 kWh
How much does it cost to run…
- A 1,500 W space heater, 4 h a day: $32.40 a month at 18 ¢/kWh.
- A 100 W TV or game console, 5 h a day: $2.70 a month.
- A 400 W gaming PC, 6 h a day: $12.96 a month.
- A 1,000 W window AC, 8 h a day: $43.20 a month.
- A 10 W LED bulb, 6 h a day: $3.89 a year.
How to lower an appliance’s running cost
Cost grows with both watts and hours, so the biggest savings come from heating and cooling: a thermostat or timer that cuts 2 hours a day off a 1,500 W heater saves $16.20 a month.
Labels show the maximum power. Fridges, ACs and heaters with thermostats cycle on and off, so a plug-in watt meter gives the real kWh — enter it in the kWh calculator.
Monthly cost by wattage (4 h a day, 18 ¢/kWh)
| Power | Energy per month | Cost per month |
|---|---|---|
| 10 | 1.2 kWh | $0.22 |
| 60 | 7.2 kWh | $1.30 |
| 100 | 12 kWh | $2.16 |
| 150 | 18 kWh | $3.24 |
| 500 | 60 kWh | $10.80 |
| 1,000 | 120 kWh | $21.60 |
| 1,500 | 180 kWh | $32.40 |
Frequently asked questions
How do I calculate the cost of electricity?
Watts × hours ÷ 1,000 = kWh, then kWh × your rate. 1,500 W for 4 hours is 6 kWh, or about $1.08 at 18 ¢.
How much does it cost to run a space heater?
A 1,500 W heater costs about $0.27 an hour at 18 ¢/kWh, or $32.40 a month at 4 hours a day.
What is the average electricity rate in the US?
About 17–18 ¢ per kWh for homes in 2026, from about 11 ¢ in some central states to over 30 ¢ in California and Hawaii. Your bill shows your exact rate.
Does standby power matter?
A device drawing 5 W all day uses 3.6 kWh a month — about 65 ¢. Ten such devices add up to $78 a year.
More calculators
Estimates only — check quantities with your supplier and local building code before you order.