Buying a portable air conditioner looks simple: pick a price, pick a brand, done. But after a decade and a half of selling these machines to Australian households, we can tell you that most disappointed buyers made the same one or two avoidable mistakes — and almost all of them happened before the unit was even switched on. Here's how to get it right.
1. Size the unit to the room — the decision that matters most
Cooling capacity is measured in kilowatts (kW). Some listings still quote BTU — divide BTU by roughly 3,400 to get kW (a 12,000 BTU unit is about 3.5 kW). The rule of thumb that served our customers well: allow about 1 kW of cooling per 8–10 m² of floor area, and round up if the room gets full western sun, has high ceilings, or sits under an uninsulated roof.
| Capacity | Room size | Typical use |
|---|---|---|
| 2.0–2.9 kW | up to ~15 m² | Bedroom, study, home office |
| 3.0–3.9 kW | ~15–25 m² | Master bedroom, small lounge |
| 4.0–5.0 kW | ~25–35 m² | Living room, open-plan area |
| 5.0 kW+ | ~35–45 m² | Large open-plan spaces |
2. Single hose or dual hose?
Every refrigerated portable must vent hot air outside through a duct. Single-hose units use room air to cool the compressor and blow it outside — simple, cheaper, but this creates slight negative pressure that draws warm air back in through gaps. Dual-hose units draw outside air for the compressor instead, so they cool larger spaces more efficiently. For a bedroom, single hose is fine. For a living area in a hot climate, dual hose (or simply a bigger single-hose unit) is worth the extra.
3. Cooling only, or reverse cycle?
A reverse-cycle portable both cools and heats, replacing a separate winter heater. The heating side is efficient — a heat pump moves roughly three units of heat per unit of electricity, versus one-for-one from a plug-in electric heater. If your climate has real winters, reverse cycle usually pays for its premium within a couple of seasons. In the tropics, save the money and buy cooling-only.
4. Noise: check the decibels before you buy
Portables keep their compressor in the room with you, so they're inherently louder than a split system. Listings quote noise in decibels: under 55 dB is excellent, 55–65 dB is typical, over 65 dB will bother light sleepers. Premium brands like De'Longhi build their reputation on quiet operation — their Pinguino range is consistently among the quietest available — while budget units trade noise for price. If it's going in a bedroom, treat the dB figure as seriously as the kW figure, and look for a dedicated sleep or night mode.
5. Running costs
Expect a portable air conditioner to draw roughly 1–1.5 kW of electricity per kW-hour of operation at full output — at typical Australian tariffs, that's in the ballpark of 30–60 cents per hour. Features that cut the bill: a thermostat with auto mode (the compressor cycles off once the set temperature is reached), a 24-hour timer, and a well-sealed window kit so you're not cooling the neighbourhood. We break the numbers down in our running-costs guide (coming soon on the articles page).
The features checklist
- Window venting kit included — check it suits your window type (sliding, sash, or door)
- Self-evaporative drainage — modern units exhaust most condensate with the hot air, so you rarely empty a tank
- Dehumidify (dry) mode — worth its weight on humid coastal nights
- Remote control or app — you will not want to get out of bed at 2am
- Castor wheels and carry handles — these machines weigh 25–35 kg
- Washable filter — a two-minute rinse each month keeps performance up
The three mistakes to avoid
- Undersizing. The bargain 2 kW unit is no bargain in a 25 m² room.
- Ignoring the venting. An unsealed window gap lets hot air pour straight back in. Take ten minutes to fit the kit properly — our installation guide shows how.
- Confusing evaporative coolers with air conditioners. They look similar in photos; they are completely different machines. An evaporative cooler will do very little on a humid Sydney day. Read the comparison if you're not sure which you're looking at.
Ready to buy?
Our current top picks for Australia cover every room size and budget, from quiet bedroom units to 4.5 kW open-plan performers — each with a link to its live price on Amazon Australia. Or browse the full range of portable air conditioners on Amazon with the sizing table above in hand.