Electricity cost tools
Electricity cost calculator
How much does a 1,500 W appliance cost to run for 8 hours a day?
A 1,500 W appliance running 8 hours per day uses 12.0 kWh of electricity. At $0.180/kWh that costs $2.16 per day, about $65.74 per average month and $788.92 per year — 365.2 kWh per average month and 4,383 kWh a year. All inputs below are editable, including the rate. This headline scenario assumes no standby draw.
Your inputs
The share of switched-on time the appliance actually draws rated power.
Applies only to the 16 h a day the appliance is switched off, not to the idle part of the duty cycle.
Use the total variable rate from your bill, including delivery charges per kWh.
$65.74
per month (30.44-day average month)
12.0 kWh per day at 1,500 W
- Per day
- $2.16
- kWh / month
- 365
- kWh / year
- 4,383
- Per year
- $788.92
Average power across 24 hours
500 W
Daily energy spread evenly over 24 hours. Includes standby draw during switched-off hours when entered.
Cost per running hour
$0.270
While the appliance is actually drawing power.
Effective duty cycle
100%
Share of switched-on time at rated power.
Method
- 1,500 W = 1.5 kW
- 1.5 kW × 8 h/day = 12 kWh/day active
- 12 kWh × 0.18 USD/kWh = 2.16 USD/day
- 2.16 × 30.436875 days = 65.744 USD/month
- 12 kWh × 365.2425 days = 4382.91 kWh/year
- 4382.91 kWh × 0.18 USD/kWh = 788.924 USD/year
Monthly figures use a 30.44-day average month, 365.24-day average year.
Assumptions
- Electricity rate of 0.18 USD/kWh (editable).
- Calculations use a year of 365.2425 days and an average month of 365.2425 ÷ 12 = 30.436875 days, so twelve average months equal one year exactly. Displayed values are rounded to 365.24 and 30.44 days, and the rounded figures do not multiply out exactly.
- Rated power is treated as real power in watts, not volt-amps.
What can change the result?
- The real power draw, which can differ from the label rating
- Duty cycle — thermostatic and cycling appliances rarely run at full power the whole time
- Hours of use, which usually vary by season
- Your electricity tariff, including per-kWh delivery charges and any time-of-use pricing
- Standing charges, which are fixed and unaffected by how much you use
$65.74/mo · 365 kWh/mo
Reading a rate off your bill
The number you want is the total variable cost per kilowatt-hour, not the supply rate alone. On most bills that means adding the energy charge and any per-kWh delivery, transmission or distribution charges together. Fixed monthly standing charges should be left out — they do not change when an appliance runs longer, so including them would distort every comparison on this site.
If you are on a time-of-use tariff, run the calculation twice with the peak and off-peak rates. The gap between those two results is exactly what shifting the load is worth.
Common appliances at typical usage
Each row is generated by the same engine, using that appliance’s own duty-cycle behaviour rather than a flat nameplate assumption. Standby means the draw during the hours the appliance is switched off — it is not applied to the idle part of a duty cycle. Appliances powered around the clock therefore have no standby hours (shown as “—”), and any continuous idle load, such as a hot tub’s circulation pump, is folded into the duty cycle instead. Every column needed to reproduce the result is shown: kWh/day = power × hours × duty + standby × off-hours, where off-hours = 24 − hours switched on.
| Appliance | Typical power | Hours · duty | Standby (off-hours) | kWh per day | Per month |
|---|---|---|---|---|---|
| Space heater | 1,500 W | 8 h · 100% | 1 W × 16 h | 12.0 kWh | $65.83 |
| Air conditioner | 1,200 W | 8 h · 60% | 2 W × 16 h | 5.79 kWh | $31.73 |
| Refrigerator | 150 W | 24 h · 35% | — | 1.26 kWh | $6.90 |
| Freezer | 120 W | 24 h · 40% | — | 1.15 kWh | $6.31 |
| Hot tub | 3,000 W | 24 h · 27% | — | 19.4 kWh | $106.50 |
| Pool pump | 1,100 W | 8 h · 100% | — | 8.80 kWh | $48.21 |
| Dehumidifier | 500 W | 24 h · 50% | — | 6.00 kWh | $32.87 |
| Gaming PC | 400 W | 4 h · 100% | 5 W × 20 h | 1.70 kWh | $9.31 |
Your next decision
- Work out which cost per kWh belongs in this calculatorUnit rate, fixed charges and effective bill rate are three different numbers.
- Compare heat pump and resistance heating costThe same delivered heat for a fraction of the electricity.
- Work out which of these loads a battery could carryTurn a consumption figure into backup runtime.
- Model how much of this a solar array could coverAnnual production against annual consumption.
- Understand the difference between watts and kilowatt-hoursPower is a rate; only energy appears on the bill.
- Check this estimate against your own meterTwo readings give a figure no appliance estimate can argue with.
- See why the bill exceeds unit rate × kWhStanding charges, taxes and time-of-use pricing.
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