Which heater is cheapest to run?
By Sithum Imarsha Last reviewed
A reverse-cycle air conditioner. It gives about 3.5 kWh of heat for each kWh of electricity, while every plug-in electric heater gives 1. Heating a 20 m² room costs about $70 a winter on reverse-cycle, $174 on flued gas and $245 on any plug-in heater, at average Australian rates.
Your result
Per winter
$245
Fan heater: 764 kWh of heat at 32c each, plus — gas supply charge for the year (only if you would cancel gas without this heater)
- An hour on full
- $0.64
- Over the cheapest
- $175
- Heat output
- 2kW
- Hours a winter
- 546
- Cheapest at this heat
- Reverse-cycle air conditioner,
$70 a winter - Rates used
- 32c/kWh · 5.06c/MJ gas
Fix the highlighted field to update.
| Heater | An hour | A winter | Extra |
|---|---|---|---|
| Fan heater | $0.64 | $245 | $175 |
| Oil column | $0.64 | $245 | $175 |
| Panel or convection | $0.64 | $245 | $175 |
| Radiant or infrared | $0.64 | $245 | $175 |
| Reverse-cycle | $0.18 | $70 | Cheapest |
| Flued gas | $0.46 | $174 | $104 |
Each row gives 2 kW of heat for 546 hours at 70% thermostat on-time. An hour is on full. Extra is the winter cost above the cheapest heater, marked "Cheapest".
How we calculated this
Work out the heat the room needs
Heat = room size × watts per square metre ÷ 1000. We start at 100 W/m², a rule of thumb from CHOICE. It is an estimate, so type your heater's kW if you know it. The same heat goes into every row of the comparison.
2 kW
Add up the heat over a winter
Heat per winter = kW × hours a day × days × thermostat on-time. A thermostat switches the heater off once the room is warm. We use the same on-time for every heater, because the room loses heat at the same rate whatever heats it.
764 kWh of heat
Price 1 kWh of heat for each heater
Plug-in electric heaters turn 1 kWh of electricity into 1 kWh of heat, so heat costs your c/kWh. A reverse-cycle air conditioner moves heat in from outside: divide the rate by its COP. Gas: c/MJ × 3.6 (1 kWh = 3.6 MJ) ÷ the heater's efficiency.
32c electric · 9.14c reverse-cycle · 22.77c gas
Multiply out your heater
Cost per winter = kWh of heat × cents per kWh of heat. Cost per hour = kW × cents per kWh of heat, running on full. When you count the gas supply charge, we add a full year of it (daily charge × 365) to the gas heater only, because you only save it by cancelling gas. It never goes into the hourly cost.
764 kWh × 32c = $245
| State | c/MJ | Supply c/day | Basis | Checked |
|---|---|---|---|---|
| New South Wales | 4.67 | 78.52 | Market average | Dated third-party source |
| Victoria | 3.82 | 90.36 | Market average | Dated third-party source |
| Queensland | 4.56 | 131.7 | Market average | Dated third-party source |
| South Australia | 5.74 | 89.89 | Market average | Dated third-party source |
| Western Australia | 5.294 | 27.61 | Regulated maximum | Official source |
| Tasmania | 5.47 | 81.7 | Market average | Dated third-party source |
| Australian Capital Territory | 5.863 | 89.65 | Standing offer | Official source |
| Australian average | 5.06 | 84.2 | Mean | Average of the states above |
Gas has no government default price. Most states use a Finder market average, the kind of plan most homes are on. WA uses the regulated maximum; the page does not say whether GST is included. The ACT uses the ActewAGL standing offer. In Victoria the Origin standing offer(4.466c/MJ and 104.962c a day) is the upper end of the market. Finder's WA figure was above the WA cap, so treat its numbers as rough. Your bill is the best source.
| What | Default | Where it comes from |
|---|---|---|
| Heat per m² | 100 W/m² | CHOICE rule of thumb: about 1 kW of heat for 10 m² (29 Nov 2021) |
| Hours a day | 6 | CHOICE: 6 hours a day for 3 months (12 May 2026) |
| Days a winter | 91 | EnergyPlans heater cost calculator default: 91 nights (June to August) |
| Thermostat on-time | 70% | No official figure. Our estimate of thermostat on-time, the same for every heater |
| Reverse-cycle COP | 3.5 | Estimate. EnergyPlans uses a seasonal COP of 3.2 to 4.3 by state. Read yours off the Zoned Energy Rating Label |
| Gas heater efficiency | 80% | Estimate. CHOICE says an unflued gas heater turns about 90% of the gas into heat, and a flued one a bit less, because some heat is lost through the flue |
Electricity rates are the same default state rates as our other tools: Canstar market average, 4 Sep 2026, except Western Australia (Synergy A1 regulated tariff from 1 Jul 2026). The state rates are: Dated third-party source, except Western Australia (Official source). A reverse-cycle COP drops in very cold weather, and an undersized unit runs less efficiently. We do not model either, so use a seasonal COP.
Sources
- CHOICE: which electric heater type is best
- CHOICE: gas heater buying guide
- CHOICE: the cheapest way to heat your home this winter
- EnergyPlans: heater cost calculator
- Energy Rating: understand the Zoned Energy Rating Label
- Victoria Government Gazette S280 (Origin gas standing offer, 1 Jul 2026)
- ActewAGL: ACT standard gas prices from 1 July 2026
- Energy Policy WA: household gas pricing
- Finder: average cost of gas (Sep 2026)
- Canstar: electricity cost per kWh
- EnergyPlans: solar feed-in tariffs July 2026
- OTTER: Tasmanian feed-in tariffs
- WA legislation: Synergy A1 tariff, charges amendment by-laws 2026 (SL 2026/140)
Compare heaters at the same heat
A cold room loses heat at the same rate whatever heats it. So the fair question is not “what does this heater cost an hour?” but “what does the same heat cost from each heater?”
Many comparisons skip this. They put a small heater against a big one, or a 20 MJ/h gas heater against a 2 kW fan heater. The bigger heater gives more heat, so of course it costs more an hour. This calculator gives every heater the same kW of heat and the same thermostat on-time. Only two things change the bill: how efficiently the heater turns energy into heat, and what that energy costs.
Every plug-in electric heater is the same
Fan, oil column, panel, convection, radiant and infrared heaters all turn 1 kWh of electricity into 1 kWh of heat. None of them is more efficient than the others. They differ in how the heat feels, how fast it arrives and how quiet they are. At the same heat, the running cost is the same.
Why reverse-cycle is cheaper: COP
A reverse-cycle air conditioner does not make heat from electricity. It uses electricity to move heat in from outside air. The COP (coefficient of performance) says how many kWh of heat you get for each kWh of electricity. A COP of 3.5 means 1 kWh of electricity gives 3.5 kWh of heat, so the heat costs your c/kWh ÷ 3.5.
COP is not fixed. It drops on very cold days. Look for the heating figures on the Zoned Energy Rating Label for your model, and use a seasonal figure rather than the best case.
Gas: MJ and kWh
Gas is sold by the megajoule (MJ). Electricity is sold by the kilowatt hour (kWh). 1 kWh is exactly 3.6 MJ. To compare them:
- Multiply your gas c/MJ by 3.6. That is the price of 1 kWh of gas.
- Divide by the heater’s efficiency (for example 0.8 for 80%). That is the price of 1 kWh of heat.
- Compare it with your c/kWh (plug-in electric) or your c/kWh ÷ COP (reverse-cycle).
A c/MJ price looks far cheaper than a c/kWh price because a megajoule is a small unit. Once you multiply by 3.6 and allow for the heat lost up the flue, the gap closes.
Gas heater labels show gas input in MJ/h. Heat output in kW = MJ/h ÷ 3.6 × efficiency. Use the output when you type a heat output into the calculator.
Most gas plans charge a higher rate for the first block of gas each day. A room heater running a few hours a day mostly uses that first block, so our defaults use the first-block rate.
The gas supply charge
Gas plans also have a daily supply charge that you pay whether or not you use gas. It only belongs in the comparison if you would cancel gas without this heater. Then you save it every day of the year, not just in winter, so the calculator adds a full year of it (daily charge × 365) to the gas heater. It never goes into the cost per hour. If you also cook or heat water with gas, you pay it anyway, so leave it out. Set “Count the gas supply charge?” to match your home.
Gas heater safety
A faulty or badly vented gas heater can fill a room with carbon monoxide, which you cannot see or smell. Fit a carbon monoxide alarm. This calculator only covers flued gas heaters.
- Victoria: Since 1 August 2022, open-flued gas heaters that cannot shut down automatically if they spill carbon monoxide cannot be sold. Source: Consumer Affairs Victoria.
- Western Australia: A prohibition order of 10 October 2022 bans the sale of open-flued gas heaters without the new safety shutdown features. Source: WA Government.
Rules differ by state. Check with your state's gas safety regulator, for example:
- NSW: NSW Fair Trading
- VIC: Energy Safe Victoria
- WA: Building and Energy
Questions
Is an oil heater cheaper than a fan heater?
No, not at the same heat. Both turn 1 kWh of electricity into 1 kWh of heat. CHOICE found running costs do not vary much between the electric heater types.
Is gas cheaper than reverse-cycle?
Usually not at today's rates. On Victorian rates, 2 kW of heat costs about $0.34 an hour from a flued gas heater and $0.16 from a reverse-cycle air conditioner. CHOICE got $317.50 for gas and $128 for reverse-cycle over a winter (at 40c/kWh, 4c/MJ and 500 hours).
What about infrared heaters?
They cost the same per kWh as any other plug-in electric heater. They warm people and surfaces rather than the air, so they can feel warmer for spot heating.
Does the gas supply charge count?
Only if you would cancel gas without the heater. Then you save a full year of it: about 28c to 132c a day in our state defaults. Set "Count the gas supply charge?" to Yes to add a year of it to the gas heater.
What is cheapest for renters?
A plug-in electric heater with a thermostat, sized to the room, or an electric blanket. CHOICE puts a single electric blanket at $48 or less a season.