Cooling 2–3 rooms: splits win, usually by $4,000–$6,000 over ten years. Cooling 4+ rooms daily in a home with roof access: zoned ducted competes on cost and wins on liveability. The industry sells ducted as the default upgrade; the numbers say it's a specific tool for bigger households.
Upfront: what each path costs installed
| Setup | Installed (Sydney) | Covers |
|---|---|---|
| 1 large split | $2,100–$3,500 | Main living area |
| 2 splits (living + bedroom) | $3,450–$5,500 | The rooms most homes actually cool |
| 3 splits (living + 2 bedrooms) | $4,800–$7,500 | Room-by-room comfort, no roof work |
| Ducted, single storey, zoned | $6,500–$9,000 | Whole single-storey home |
| Ducted, two storey, zoned | $9,000–$12,000 | Two-storey family home |
Sydney ranges from our database; your suburb's numbers are on its cost page.
Running cost: the part quotes never show
This is where splits quietly win for smaller households. A split cools the room you're in; ducted conditions the whole zone set. Even well-zoned ducted runs one large compressor cooling two occupied rooms with a 14kW ducted system is like doing the school run in a truck. Over ten summers on a typical tariff, two daily-use splits cost roughly $2,000–$3,000 to run; whole-home ducted on the same usage pattern runs $4,500–$7,000. Zoning discipline narrows the gap; it doesn't close it.
Run both totals for your home Room count + city → upfront and 10-year running cost for each path, instantly.What ducted buys that the spreadsheet misses
- Whole-home coverage, hallways, bathrooms mid-renovation aside, no hot dead zones.
- Invisibility, grilles instead of wall units; one discreet outdoor unit instead of two or three.
- Resale story, buyers like it; just don't count it as an investment (see FAQ).
- One system to service, a single service visit, not one per unit.
Those are real. Price them consciously, "we want ducted because we want it" is a legitimate reason to spend the extra $5,000+. What we push back on is ducted sold as the automatic move for a 3-bed house where two rooms get cooled.
The crossover rule
From our quote data, the honest rule of thumb: count the rooms you'd genuinely cool on a hot week. At 1–2, splits, no contest. At 3, splits still usually win, unless roof access is perfect and the ducted quote comes in low. At 4+, get both paths quoted and let the numbers decide, that's the range where installer pricing, not category, settles it.
At the crossover? Ask for both paths in the same visit, installers sharpen both numbers when they know the comparison is live.
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