Ducted vs split system air con: install and running costs compared
A single split system typically costs {range:air-conditioning:mid} fitted; ducted jobs price per zone, so the real comparison is about rooms, not units.
The quick answer
A single split system for a typical room or small zone runs to about $9,050 fitted, with most quotes falling between $7,050 – $11,700 (incl. GST). Ducted systems don't have one fixed price in the same way — they're sized to the whole house, not a single room, so a ducted quote is really the sum of however many zones your home needs, plus ductwork, a central unit and often ceiling work. For most homes, that means ducted ends up costing noticeably more upfront than even two or three split systems combined, but it cools or heats the whole house from one thermostat instead of room by room.
This is the comparison our Split system air conditioning guide doesn't spell out, because it's built around sizing a single split system. Here's how the two options actually stack up once you factor in install and running costs together.
Install cost: split systems scale with rooms, ducted scales with the house
Our live cost model prices split system air conditioning per typical job (three rooms as a default), with the install cost moving with the quality of the unit and the complexity of the installation:
| Tier | Typical split system cost |
|---|---|
| Basic | $4,700 |
| Mid-range | $9,050 (usual range $7,050 – $11,700) |
| Premium | $17,500 |
That's for cooling (and usually heating) three rooms with separate indoor heads and one or more outdoor condensers. Want to cool a fourth or fifth room? You're generally adding another head and outdoor unit, or stepping up to a multi-head system — the cost rises in fairly predictable steps per room.
Ducted systems don't work that way. Instead of one head per room, a central unit in the roof space feeds ducting to vents in every room you want conditioned, controlled by one or more zone dampers. Because the whole house is wired into a single system, the install price depends heavily on:
- How many zones the ductwork is split into (more zones means more dampers and controls)
- Roof space access — a single-storey home with a simple roof is far cheaper to duct than a double-storey or complex roofline
- Ceiling and bulkhead work if there's nowhere to hide the ducting
- Capacity, since one central unit has to be sized for the whole house, not just one room
As a rule of thumb, a ducted retrofit covering a typical three-to-four-bedroom home tends to land well above the cost of fitting split systems to the same number of rooms, because you're paying for ductwork, zoning and a larger central unit on top of the indoor/outdoor hardware. The gap narrows in new builds, where the ducting goes in before the ceiling does.
Running costs: the real trade-off
Split systems have an efficiency advantage that often gets missed: you only run the rooms you're actually using. A bedroom split can sit off all day while the living room one runs flat out, and each head modulates its own output. Multi-room comfort from splits comes at the cost of more indoor units to maintain and more remotes or apps to manage.
Ducted systems can zone too, but even with zoning, a central unit pushing air through long duct runs generally loses some efficiency to duct leakage and the energy needed to run the fan across the whole network — whether you're using two zones or eight. For a household that genuinely wants the whole house conditioned most of the time, that trade-off disappears; ducted can be the more convenient and comfortable option even if it's not always the cheapest to run.
The practical takeaway: if you mostly cool one or two rooms (main bedroom, living area), split systems usually cost less to install and run. If you want consistent temperature through most of the house, ducted's higher install cost buys convenience and even coverage that multiple splits can't easily match.
Hidden costs on both sides
- Switchboard and circuit work — larger split systems and any ducted unit often need a dedicated circuit; older switchboards may need upgrading first
- Condensate drainage — routing drain lines, especially for ceiling-mounted ducted units
- Outdoor unit placement — easements, noise rules near boundaries, and strata or heritage approval in some areas
- Maintenance access — ducted filters and coils are harder to reach than a wall-mounted split head, which can add to servicing costs over time
Quotes you receive should already include GST — ours do too, so the figures above are what you'd actually pay.
Cutting running costs further
Because both systems are significant electricity users in summer, it's worth looking at what feeds them. Pairing either option with rooftop solar is one of the more effective ways to offset running costs over the system's life — see our Solar panels guide for current installed costs.
Getting a fair quote
Because ducted quotes vary so much with zoning and roof access, and split system quotes vary with brand and installation difficulty, get at least two or three quotes before deciding, and check what's actually included (brand and model, number of zones, warranty length, and who's doing the electrical work). If a quote looks out of step with the figures here, run it past our "is my quote fair" tool before you sign anything.