Ducted vs Split System Cost Comparison

Understanding ducted vs split system cost comparisons in Australia

What each system actually costs installed in 2026

A single wall-mounted split is the entry point at $1,800 to $4,200 supplied and installed, covering everything from a small 2.5 kW bedroom head to a 7.1 kW unit sized for an open plan living area. Step up to a multi-split, meaning three to five indoor heads running off one or two outdoor condensers, and you are at $6,500 to $14,000. Fully installed ducted reverse cycle mostly lands $9,000 to $18,000 for a typical three to four bedroom home, working out at roughly $80 to $120 per square metre of conditioned floor area, and $17,000 to $25,000 or more once you add a fifth bedroom or a second storey. The spread inside each band is driven less by the brand on the box than by pipe runs, roof access, and how much electrical work the switchboard needs.

The running cost picture is not what most people assume

The common belief is that ducted is the efficient choice because one big compressor is more efficient than several small ones. That is true of the equipment and false of the household. A ducted system draws roughly 3 to 6 kWh an hour, which at 2026 tariffs is about $0.90 to $1.80 an hour, giving a three to four bedroom home $600 to $1,300 a year. A multi-split running two heads on a summer evening is doing a fraction of that work. The variable that decides it is zoning discipline. Without zoning, ducted conditions the whole house every time anyone wants one room cool, and it loses the running cost argument outright. With good zoning it cuts consumption 20 to 40 per cent and becomes genuinely competitive on a per-room basis. So the honest framing is that ducted is efficient for people who want the whole house conditioned, and expensive for people who want one room conditioned.

Where each option clearly wins

A single split wins when the problem is localised. One hot west-facing living room, a converted garage, a bedroom over a garage, or an apartment where the body corporate limits what you can put on the wall. It is also the only sensible choice for a rental or a property you expect to sell inside five years, because you will not recover ducted money at sale. Multi-split wins in homes with no usable roof cavity, which covers most flat-roofed extensions, many double-brick terraces, and apartments outright. It also wins where household members genuinely want different temperatures, since each head is independently controlled by default rather than by an add-on zone controller. Ducted wins on whole-home comfort, on quietness inside the room, and on visual cleanliness, and it is the only one of the three that reliably shows up in real estate listings as a selling feature.

Australian climate considerations

Climate zone should change the answer more than it usually does. In hot dry inland areas such as Western Sydney, Adelaide, Perth's east and regional Queensland, whole-home cooling load is real and sustained, and ducted earns its cost because the house needs conditioning as a whole for months at a time. In the cold southern belt, Melbourne, Canberra, Hobart and alpine New South Wales, the case is about heating rather than cooling, and reverse cycle ducted is competing against gas ducted heating rather than against splits. In humid subtropical Brisbane and the northern coast, dehumidification matters as much as temperature, and a correctly sized split running longer at lower output removes moisture better than an oversized system that short cycles. In mild coastal Sydney, Newcastle and Wollongong, plenty of homes are honestly served by two or three splits, and the ducted upgrade is a comfort and aesthetics purchase rather than an energy one.

What installers actually recommend and why

Ask an experienced installer off the record and the recommendation usually splits on ownership horizon and roof access. If the roof cavity is tight, the trusses are close set, or the ceiling is a raked cathedral, they will steer you to multi-split because forcing ducts into a bad cavity produces long, kinked runs, poor airflow at the far outlets, and a system that never performs to its rating. If you are staying ten years or more in a standard truss-roof house, they will steer you to ducted, because the ductwork is a one-off cost that outlives the compressor and the second unit in 15 years is a much cheaper job than the first. The recommendation they will not volunteer unless asked is the hybrid: ducted through the bedroom wing where quiet and discreet matters, plus one high-capacity split in the open plan living area where the load is concentrated. That configuration often costs less than full ducted and outperforms it on the hottest afternoons.

Sizing, and the errors that cost the most

Oversizing is the expensive mistake. An oversized system reaches setpoint fast, shuts down, leaves humidity behind, and short cycles its way through a shortened compressor life. Undersized return air is the other, and it is more common on ducted than anyone admits, because the return grille is the least visible part of the install and the easiest place to save an hour. Ask for the heat load calculation in writing rather than a capacity picked off floor area, and ask what the return air grille free area is. A quote that cannot answer either question has been eyeballed, and the gap between an eyeballed system and a designed one shows up every January.

Making the call

Work it as a total cost of ownership over the years you will actually own the house. Take the installed price gap, divide it by your realistic remaining ownership years, and compare that annual figure to the running cost difference for the rooms you genuinely condition. For a household that conditions two rooms and moves in six years, splits win comfortably. For a family conditioning a whole four bedroom home in a hot inland climate for the next fifteen years, ducted with proper zoning wins on both comfort and lifetime cost. Between those two poles, multi-split is the answer far more often than the market share suggests, which is why it is the option most quotes quietly skip.