Electricity Cost Calculator
What an appliance costs to run, from its wattage, daily use and your electricity price.
- Energy used (kWh)15.0
- Electricity cost$3.75
Inputs used
- Appliance power100 W
- Hours used per day5
- Over a period of30 days
- Electricity price per kWh$0.25
About this calculator
An appliance's running cost is its power draw times the hours it runs times your electricity price. Power in watts divided by 1,000 gives kilowatts; multiplied by hours it gives kilowatt-hours (kWh) — the unit on your bill.
A 100 W device running 5 hours a day uses 0.5 kWh daily, 15 kWh over a month — at 0.25 per kWh, about 3.75 a month. The surprises are usually the always-on loads: a 2,000 W heater is expensive per hour, but a 15 W router running 24/7 quietly uses more than 10 kWh a month.
The wattage on a nameplate is the maximum draw; many appliances (fridges, washing machines) cycle and average far less. A cheap plug-in energy meter gives the real figure.
Quick reference
Monthly running cost by wattage and hours per day
Cost over 30 days at $0.25 per kWh, by appliance wattage (row) and hours used per day (column).
| Appliance power | 1 | 2 | 4 | 8 | 12 | 24 |
|---|---|---|---|---|---|---|
| 15 W | $0.11 | $0.22 | $0.45 | $0.90 | $1.35 | $2.70 |
| 50 W | $0.38 | $0.75 | $1.50 | $3.00 | $4.50 | $9.00 |
| 100 W | $0.75 | $1.50 | $3.00 | $6.00 | $9.00 | $18.00 |
| 500 W | $3.75 | $7.50 | $15.00 | $30.00 | $45.00 | $90.00 |
| 1,000 W | $7.50 | $15.00 | $30.00 | $60.00 | $90.00 | $180.00 |
| 1,500 W | $11.25 | $22.50 | $45.00 | $90.00 | $135.00 | $270.00 |
| 2,000 W | $15.00 | $30.00 | $60.00 | $120.00 | $180.00 | $360.00 |
| 3,000 W | $22.50 | $45.00 | $90.00 | $180.00 | $270.00 | $540.00 |
Frequently asked questions
How do I calculate the cost of running an appliance?
Divide the wattage by 1,000 to get kilowatts, multiply by the hours it runs to get kilowatt-hours, then multiply by your price per kWh. A 100 W device for 5 hours a day over 30 days uses 15 kWh, about $3.75 at $0.25 per kWh.
How much does it cost to run a 1500W heater?
At 4 hours a day for 30 days it uses 180 kWh, about $45 at $0.25 per kWh — roughly $1.50 an hour to run. Heaters are among the most expensive household loads because of their high wattage.
Why do always-on devices cost more than they seem?
Because they run every hour of every day. A 15 W router left on 24/7 uses about 10.8 kWh a month — around $2.70 — quietly outrunning a high-wattage appliance you switch on only briefly.
What is a kilowatt-hour?
A kilowatt-hour (kWh) is the energy of a 1,000 W device running for one hour — the unit your electricity bill charges by. A 2,000 W appliance uses 1 kWh in 30 minutes; a 100 W one takes 10 hours to use the same.
Embed this calculator on your site
Paste this HTML where you want the calculator to appear. It stays free, works on any site, and updates automatically. Adjust the height to taste.
Results are informational only — not financial, medical or legal advice.