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Why most "efficient heater" advice gets it wrong
Search for the most energy-efficient heater and you'll get roundups ranking fan heaters against oil columns against panel heaters, hinting that some plug-in heaters are meaningfully cheaper to run than others. For resistive electric heaters, that's simply not true, and the rankings quietly mislead.
Every resistive heater, whatever its shape or price, is about 100% efficient: it turns electricity into heat one-for-one. So two heaters of the same wattage cost the same to run, full stop. The differences are comfort, controls and safety, not efficiency. The only thing that changes running cost is leaving resistance behind for a heat pump.
How heater efficiency actually works
There's a hard physical ceiling on resistive heating, and a way to beat it.
The resistive ceiling
Fan heaters, oil columns, panel heaters, radiant bar heaters and electric in-slab all work the same way: pass current through a resistor and it gets hot. They're all about 100% efficient, which sounds great until you realise it means one unit of heat per unit of power, and not a fraction more. A 2,400 watt heater draws 2.4 kW the whole time, about 72 cents an hour at a 30 c/kWh rate, whether it cost $40 or $400. Style and comfort differ; running cost doesn't.
Breaking the ceiling with a heat pump
A reverse-cycle air conditioner isn't resistive. It uses power to move heat from outside air indoors, so it delivers three to five units of warmth per unit of electricity. That's the only way to get below the resistive ceiling, and it's why the genuinely efficient heater is the one most people file under "cooling". For reverse-cycle units the Zoned Energy Rating Label (ZERL) is worth reading, because there efficiency really does vary.
Resistive vs reverse-cycle: see the ceiling
Pick any resistive heater wattage and compare it with a reverse-cycle unit making the same heat. Notice the resistive cost doesn't care which type of heater it is. Every figure also appears in the worked example below.
Heater running cost
Per winter, same heat. Edit any input.
A resistive heater's electricity draw equals its rated power, whatever the type or price. Reverse-cycle = same heat output ÷ COP × rate. Rates are editable defaults, not your plan.
Worked example (the calculator's default). A 2,400 W heater, 4 h/day for 100 winter days at 30 c/kWh, vs a reverse-cycle unit (COP 4) making the same heat:
| Heater | Electricity drawn | Cost for the winter |
|---|---|---|
| Any resistive (fan, oil, panel, radiant) | 960 kWh | ~$288 |
| Reverse-cycle (COP 4) | 240 kWh | ~$72 |
The $40 heater and the $400 heater both land on that $288 line. Only the reverse-cycle breaks it, at about a quarter of the cost for the same warmth.
How Aussies overpay without realising it
A pricey panel heater marketed as efficient still costs the same to run as a cheap fan heater of the same wattage. You paid for the look.
Oil columns feel gentler and hold warmth, but for the same output they draw the same power as any other resistive heater.
A plug-in heater as your main winter heat source is the dearest option going. Keep it for quick spot warmth, not daily heating.
The reverse-cycle unit you bought for summer is the efficient heater you've been looking for, sitting unused in winter.
The insider insight: "efficient" is a marketing word on a resistive heater
Watch the language in the heater aisle. Resistive heaters get sold with words like "energy efficient", "eco" and "smart", and technically they're all 100% efficient, so the claim isn't even false. It's just meaningless for comparing running cost, because they're all 100% efficient. The marketing leans on a true-but-useless fact to imply a saving that isn't there.
The genuinely useful number, efficiency above 100%, only exists for heat pumps, because they move heat rather than make it. A reverse-cycle unit's "300 to 500% efficiency" (a COP of 3 to 5) isn't marketing spin; it's the physics of moving heat instead of generating it. So when you see "efficient" on a plug-in heater, read it as "looks nice"; when you want a heater that's actually cheaper to run, you want the one with a COP, and that's the aircon.
What you should actually do
| Do this | Why it works |
|---|---|
| Use a reverse-cycle unit as your main heater | The only heater that beats the resistive ceiling, at roughly a quarter of the cost. |
| Don't pay extra for an "efficient" resistive heater | Same wattage means same running cost; the premium buys looks, not savings. |
| Keep a plug-in heater for spot warmth only | Fine for a quick boost in one spot; ruinous as daily whole-evening heat. |
| Read the ZERL on reverse-cycle units | That's the one place efficiency genuinely varies and the label helps. |
| Set 18–20°C and heat occupied rooms | Cuts the run-time of whatever heater you use. |
| In VIC, NSW, SA, QLD, ACT: compare plans against the DMO/VDO | A better rate lowers the cost of every heating hour. |
In Western Australia (Synergy) and the Northern Territory (Power and Water) there's no retailer to switch to. See our home heating and heating savings guides.
Why this matters right now
With power prices high, the difference between resistive and reverse-cycle heating is real money every winter night. And as marketing leans harder on "efficient" labels, knowing they mean nothing on a plug-in heater saves you from paying a premium for a saving that doesn't exist.
The takeaway: for plug-in heaters, price tells you nothing about running cost. The only efficient heater is the one with a COP, and you may already own it.
Frequently asked questions
Current figures — last updated 2026-06-13
All values in AUD and Australian units. Volatile figures change; check your own plan before relying on them.
| Resistive heater efficiency | ~100% (1 unit of heat per unit of power) |
|---|---|
| Reverse-cycle heating efficiency (COP) | 3–5 units of heat per unit of power |
| Cost of a 2.4 kW resistive heater | ~72 c/hour at 30 c/kWh |
| Typical electricity rate | ~25–35 c/kWh [verify: your plan] |
| Recommended set point | 18–20°C |
| Reference price (NSW, SA, SE QLD / VIC) | AER DMO / ESC VDO [verify: current value] |
Sources: energy.gov.au, Zoned Energy Rating Label (ZERL) scheme, Australian Energy Regulator (DMO), ESC Victoria (VDO).