Appliance running costs
Cost to run a space heater
How much does a 1,500 W space heater cost to run?
A 1,500 W space heater switched on 8 hours per day at 100% duty cycle uses 12.0 kWh of electricity per day. At $0.180/kWh that is $2.16 per day, about $65.83 per average month and $789.98 per year — 4,389 kWh over the year. Those figures assume a typical wattage and a typical usage pattern; change any input below to match your own appliance and tariff.
Your inputs
Typical example — replace this 1,500 W default with your appliance’s actual rating for a better estimate.
A thermostat cuts this appliance out once at temperature — typical range around 100%.
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.
$65.83
per month (30.44-day average month)
12.0 kWh per day at 1,500 W
- Per day
- $2.16
- kWh / month
- 366
- kWh / year
- 4,389
- Per year
- $789.98
Average power across 24 hours
501 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
- 1 W standby × 16 h/day off = 0.016 kWh/day standby
- 12 + 0.016 = 12.016 kWh/day total
- 12.016 kWh × 0.18 USD/kWh = 2.163 USD/day
- 2.163 × 30.436875 days = 65.831 USD/month
- 12.016 kWh × 365.2425 days = 4388.754 kWh/year
- 4388.754 kWh × 0.18 USD/kWh = 789.976 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.
- 1 W standby draw for the 16 hours a day the appliance is switched off. Standby applies only outside the switched-on hours, not to the idle part of the duty cycle, and is included in every kWh and cost figure below.
- Rated power is treated as real power in watts, not volt-amps.
What can change the result?
- Whether the thermostat cycles the element off (duty cycle)
- Heater setting — many units have 750 W and 1,500 W modes
- Room size, insulation and outdoor temperature
- Hours of use, which typically rise sharply in cold snaps
$65.83/mo · 366 kWh/mo
How a space heater actually draws power
A resistance heater has no efficiency trick to play: while the element is on it draws essentially its full rated power. The only thing that reduces consumption is the thermostat cutting the element out once the room reaches temperature. In a draughty or large room a 1,500 W heater can run close to 100% of the time; in a small, well-insulated room the same heater may only be on a third of the time.
Treat the number below as the cost of the heater running at full power for the hours you set. If your heater has a thermostat and the room reaches temperature, lower the duty cycle to match — 50% duty roughly halves the cost. Note that every watt of a resistance heater becomes one watt of heat, so no 'energy-saving' portable heater of the same wattage is cheaper to run.
Cost at different usage patterns
All rows use 1,500 W at 100% duty and $0.180/kWh. Only the hours change.
| Hours per day | kWh per day | Per day | Per month | Per year |
|---|---|---|---|---|
| 4 h/day | 6.02 kWh | $1.08 | $32.98 | $395.78 |
| 6 h/day | 9.02 kWh | $1.62 | $49.41 | $592.88 |
| 8 h/day | 12.0 kWh | $2.16 | $65.83 | $789.98 |
| 12 h/day | 18.0 kWh | $3.24 | $98.68 | $1,184 |
Cost across the typical wattage range
Units in this category typically range from 750 W to 1,500 W. All rows use 8 h/day at 100% duty.
| Power rating | kWh per day | Per day | Per month | Per year |
|---|---|---|---|---|
| 750 W | 6.02 kWh | $1.08 | $32.96 | $395.51 |
| 1,500 W | 12.0 kWh | $2.16 | $65.83 | $789.98 |
| 1,500 W | 12.0 kWh | $2.16 | $65.83 | $789.98 |
Worth knowing
Worth knowing
Your next decision
- Heat pump vs resistanceCOP explained, with the cost difference calculated.
- Electricity cost calculatorWatts and hours in, cost per day, month and year out.
- DehumidifierWhat a dehumidifier costs to run, using realistic behaviour rather than nameplate watts.
- Why the rating plate overstates what this appliance usesDuty cycle and part-load operation, which set the figures above.
- What the standby watts add over a yearThe off-hours component of this appliance's annual total.
Your next decision
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Electricity cost tools
- Electricity cost calculatorWatts and hours in, cost per day, month and year out.
- Cost per kWh explainedThree different costs per kWh on one bill, and which one belongs in a calculator.
- Appliance wattage calculatorA configurable appliance list: what this combination draws, and what it costs.
- Watts to run a houseRunning, average and startup watts — separated, not averaged into one range.
Defaults on this page come from the published default registry and the formulas are documented in the methodology.