Case 1
- Power
- 100W
- Hours per day
- 5h
- Price per kWh
- 0.3
0.15
Open with these valuesElectricity Cost Calculator
0.15per day
Result: 0.15 per dayWatts times hours divided by 1000 gives kilowatt-hours; multiply by your price per kWh for the cost. A 100 W device run 5 hours a day uses 0.5 kWh and costs 0.15 at a price of 0.30. Multiply by 30 for a month, by 365 for a year.
The numbers at a glance
Held fixed: Power 100 W, Hours per day 5.0 h.
| Price per kWh | Result |
|---|---|
| 0.0000 | 0.00 |
| 0.1000 | 0.05 |
| 0.2000 | 0.10 |
| 0.3000Your value | 0.15 |
| 0.4000 | 0.20 |
| 0.5000 | 0.25 |
| 0.6000 | 0.30 |
Worked examples
Case 2
- Power
- 2000W
- Hours per day
- 1h
- Price per kWh
- 0.3
0.60
Open with these valuesCase 3
- Power
- 60W
- Hours per day
- 24h
- Price per kWh
- 0.25
0.36
Open with these valuesHow it's calculated
Cost = watts × hours ÷ 1000 × price per kWh
- StepEnter the wattage from the appliance label or nameplate.
- StepEnter how many hours a day it actually runs.
- StepEnter your own price per kWh, from your bill or tariff.
- ResultRead the daily cost; times 30 is a month, times 365 a year.
Reference table
| Watts, hours, price | Per year | Cost per day |
|---|---|---|
| 5, 24, 0.30 | 13.14 | 0.04 |
| 100, 5, 0.30 | 54.75 | 0.15 |
| 60, 24, 0.25 | 131.40 | 0.36 |
| 2000, 1, 0.30 | 219.00 | 0.60 |
| 100, 24, 0.30 | 262.80 | 0.72 |
Questions
How do I work out what an appliance costs to run?
Multiply the watts by the hours it runs each day, divide by 1000 for kilowatt-hours, then multiply by your price per kWh. A 100 W device run 5 hours a day at a price of 0.30 uses 0.5 kWh and costs 0.15 a day.
Where do I find an appliance's wattage?
On its label, nameplate or power supply, printed as a number followed by W or watts. If only volts and amps are given, multiply them together. For devices whose draw varies, the rating is usually the maximum.
What is a kilowatt-hour?
It is the energy a 1000-watt device uses in one hour, and it is the unit your electricity is billed in. That is why the price you enter is a price per kWh. A 100 W device running 10 hours also uses exactly 1 kWh.
Which currency and which price should I use?
Whichever you like — the result carries no currency symbol, so it comes back in the same one you typed. Take the price from your own bill; the preset is only a starting point and electricity prices differ widely between countries and years.
Does standby power really add up?
Yes. A device drawing a few watts while switched off still runs 24 hours a day. Enter its standby wattage with 24 hours to see the yearly figure — 5 W at a price of 0.30 is about 13 a year.
Sources and last check
Information, not professional advice.