Electricity Cost Calculator
Electricity cost = watts × hours ÷ 1,000 × price per kWh. A 1,500 W space heater running 8 hours a day uses 12 kWh a day, which costs $2.16 a day and $65.70 a month at 18 cents per kWh.
By the Calculators With Steps team · Updated November 10, 2026 · How we check our math
- Cost per hour
- $0.270
- Cost per day of use
- $2.16
- Cost per year
- $788.40
- kWh per day
- 12 kWh
- kWh per month
- 365 kWh
- kWh per year
- 4,380 kWh
Step-by-step working
- Power in kilowatts = 1,500 W ÷ 1,000 = 1.5 kW
- Energy per day = 1.5 kW × 8 h = 12 kWh
- Cost per day = 12 kWh × $0.180 = $2.16
- Energy per year = 12 kWh × 365 days of use = 4,380 kWh
- Cost per month = 4,380 kWh ÷ 12 × $0.180 = $65.70
Typical wattage of common appliances
| Appliance | Typical power | Typical range | Cost per hour at $0.180/kWh |
|---|---|---|---|
| LED bulb (60 W equivalent) | 9 W | 8–12 W | $0.002 |
| Wi-Fi router | 10 W | 5–20 W | $0.002 |
| Laptop | 50 W | 30–100 W | $0.009 |
| Ceiling fan | 60 W | 15–90 W | $0.011 |
| 55-inch LED TV | 100 W | 60–150 W | $0.018 |
| Refrigerator (while the compressor runs) | 150 W | 100–250 W | $0.027 |
| Desktop computer | 200 W | 100–450 W | $0.036 |
| Window air conditioner | 1,000 W | 500–1,500 W | $0.180 |
| Microwave oven | 1,100 W | 600–1,500 W | $0.198 |
| Space heater | 1,500 W | 750–1,500 W | $0.270 |
| Hair dryer | 1,500 W | 1,000–1,875 W | $0.270 |
| Electric kettle | 1,500 W | 1,200–3,000 W | $0.270 |
| Electric oven | 2,400 W | 2,000–5,000 W | $0.432 |
| Central air conditioner (3 ton) | 3,500 W | 3,000–4,000 W | $0.630 |
| Electric clothes dryer | 4,000 W | 1,800–5,000 W | $0.720 |
| Electric water heater | 4,500 W | 3,000–5,500 W | $0.810 |
| EV charger (Level 2) | 7,200 W | 3,300–11,500 W | $1.296 |
Devices with thermostats or compressors (fridges, AC, heaters, water heaters) cycle on and off, so they draw full power for only part of the time. A plug-in energy monitor gives the most accurate kWh figure.
How to use the electricity cost calculator
- Enter the power rating in watts or kilowatts. It is printed on the appliance label, the power adapter or in the manual.
- Enter how many hours a day it runs and how many days a week.
- Enter the number of devices if you have several of the same kind.
- Enter your electricity rate per kWh. It is on your bill, sometimes called the energy charge or price per unit.
You get the cost per hour, per day of use, per month and per year, the kWh used, and a table of typical wattages with the hourly cost at your rate.
Electricity cost formula
kWh = watts × hours ÷ 1,000
Cost = kWh × price per kWh
A kilowatt-hour is 1,000 watts used for one hour, or 3.6 megajoules of energy. The calculator spreads your weekly pattern over a 365-day year and shows a month as one-twelfth of that year, so the monthly figure is an average.
Worked example: a space heater
A 1,500 W space heater runs 8 hours a day, every day, at an electricity rate of $0.18 per kWh.
| Step | Working | Result |
|---|---|---|
| Power in kW | 1,500 ÷ 1,000 | 1.5 kW |
| Energy per day | 1.5 kW × 8 h | 12 kWh |
| Cost per day | 12 × $0.18 | $2.16 |
| Energy per year | 12 × 365 | 4,380 kWh |
| Cost per month | 4,380 ÷ 12 × $0.18 | $65.70 |
| Cost per year | 4,380 × $0.18 | $788.40 |
Running costs scale directly with hours. A 1,000 W window air conditioner used 8 hours a day uses about 243 kWh a month, or $43.80 at the same rate.
What electricity costs in the U.S.
The U.S. Energy Information Administration reports that the average residential price was 18.19 cents per kWh from January to August 2026, up from 17.03 cents over the same months of 2025. The calculator’s default of $0.18 is close to that average. Rates differ a great deal by state and by plan, and some utilities charge more at peak times, so use the rate from your own bill. Your bill also includes fixed monthly charges, delivery fees and taxes that do not change with how much you use, so the total per kWh you pay can be higher than the energy rate alone.
Electricity units and cost in India
In India, electricity bills count consumption in units, and one unit is one kWh. Tariffs are set by each state’s electricity regulatory commission and usually rise in slabs as monthly use increases, with fixed charges and duties added on top. Use your bill’s per-unit rate for the slab you are in and choose INR in the currency menu. For example, a 1.5 kW air conditioner run for 8 hours a day uses 12 units a day, or 365 units a month. At ₹8 a unit that is about ₹2,920 a month. Inverter ACs and star-rated models draw less than their full rating once the room is cool, so measured use is often lower.
Typical appliance wattage
The table in the calculator lists typical power draws, such as about 9 W for an LED bulb, 100 W for a 55-inch LED TV, 1,500 W for a space heater and 7,200 W for a Level 2 EV charger. These are typical figures, not exact ones. Your appliance’s label is the better source, and a plug-in energy monitor gives the most accurate reading of what it actually uses.
Some devices do not run at full power all the time:
- Refrigerators and freezers cycle on and off, so the compressor runs only part of each hour.
- Air conditioners, heaters and water heaters switch off once they reach the set temperature.
- Computers and TVs draw less when idle and a few watts on standby.
For these, the annual kWh figure on the EnergyGuide label (U.S.) or the star label (India) is a better starting point than the wattage.
Ways to cut the cost
- Replace incandescent bulbs with LEDs, which use about 85% less power for the same light (9 W instead of 60 W).
- Use timers and smart plugs for things that do not need to run all day.
- If your utility offers time-of-use pricing, run dishwashers, laundry and EV charging during off-peak hours.
- Turn off devices at the wall to stop standby draw.
To compare the running cost of an electric car with a gasoline one, pair this tool with the fuel cost calculator. To convert between kWh, BTU, joules and calories, use the unit converter.
Electricity Cost Calculator: frequently asked questions
How do I calculate electricity cost from watts?
Multiply watts by hours of use and divide by 1,000 to get kWh, then multiply by your price per kWh. A 100 W TV used 5 hours a day uses 0.5 kWh a day, which costs 9 cents a day or about $2.74 a month at $0.18 per kWh.
What is the average electricity cost per kWh in the U.S.?
The average U.S. residential price was 18.19 cents per kWh for January to August 2026 and 18.16 cents in August 2026, according to preliminary EIA data. Rates vary widely by state and by utility plan.
How much does it cost to run a 1,500 W space heater?
A 1,500 W heater uses 1.5 kWh each hour it runs at full power. At $0.18 per kWh that is $0.27 an hour, $2.16 for 8 hours and about $65.70 a month if used 8 hours every day.
What is a unit of electricity?
One unit on an electricity bill is one kilowatt-hour (kWh): 1,000 watts used for one hour. A 1.5 kW air conditioner running 8 hours uses 12 units.
How do I calculate electricity cost for an EV?
Multiply the energy added (kWh) by your rate. A 7.2 kW Level 2 charger running for 4 hours adds about 28.8 kWh, which costs $5.18 at $0.18 per kWh. Some energy is lost as heat while charging, so the meter reading is a little higher.
How do I calculate electricity cost from a meter reading?
Subtract the earlier meter reading from the later one to get the kWh used, then multiply by your rate. If the meter went from 12,400 to 12,700 kWh, you used 300 kWh, which costs $54 at $0.18 per kWh before fixed charges and taxes.
How do I find the watts if the label only shows amps?
Multiply volts by amps. A device rated at 10 amps on a 120-volt U.S. circuit draws up to 1,200 watts. Many devices draw less than their maximum rating most of the time.
How we checked this page: every figure in the examples and FAQs above is produced by this calculator and verified by automated tests against known answers, and the rules and rates come from the sources below. Last updated . Spotted a problem? Tell us.