Ducted sizing guide
Design Your Ducted System
Answer six quick questions for an indicative system size, number of zones and outlets. It takes about a minute, and your free site inspection confirms the size.
5.0 from 292 Google reviewsSix questions
What size ducted system does my home need?
Most of the answer comes from the floor area you want to cool, adjusted for insulation, sun, ceiling height and storeys. Fill in the questions below for an indicative capacity in kilowatts, a suggested number of zones and outlets. It is a guide only; your free site inspection confirms the size before we quote.
Your indicative estimate
Your estimate will appear here.
Nothing is sent until you choose to add it to an enquiry.
- Capacity
- –
- Zones
- –
- Outlets
- –
Indicative only, based on the rule of thumb below. Your free site inspection confirms the size.
Transparent maths
How does this estimate work?
We start from 0.09 kW of capacity per square metre of air-conditioned floor area, a planning figure for a zoned ducted system where not every room runs at once. That is multiplied by the factors in the table, then shown as a range of plus or minus 10% and rounded to the nearest 0.5 kW.
| Input | Rule |
|---|---|
| Floor area | 0.09 kW per m² (for example, 150 m² × 0.09 = 13.5 kW) |
| Ceiling insulation | Good × 0.9; average or not sure × 1; poor or none × 1.15 |
| West or north-facing glass | × 1.1 |
| High or raked ceilings | × 1.15 |
| Double storey | × 1.05 (upper floors run warmer) |
| Zones | One per bedroom and living area. ZoneTouch handles up to 6; above that, small rooms are grouped or AirTouch 5 is quoted. |
| Outlets | One per room, or one per 20 m² of floor area, whichever is more. |
These are general planning figures, not a heat-load calculation. They do not account for window sizes, shading, wall insulation, how airtight the house is, how many people use each room or where the return air can go. That is what we measure on site.
The next step
Why does the site inspection confirm the size?
Because the roof space and the rooms decide the design. At the free inspection we check the roof space for room to run ducts, where the outdoor unit can go, the switchboard, the windows and sun, and how you use each room. Then we design the zones and outlets and send a fixed written quote.
- Roof access, height and trusses, which decide duct routes and unit placement.
- Outdoor unit position: clearance, noise near bedrooms and drainage.
- Electrical capacity, checked by our own electricians. Larger systems can need three-phase power.
- Outlet positions for even airflow, and a return air grille that lets air flow back to the unit.
Send it to us
Get your ducted system designed and quoted
Send your estimate with your details and we will call to book a free on-site inspection. Your answers from the sizing guide go into the message box, so you do not have to repeat them. Edit or add anything you like before you send.
Prefer to see what is included first? Look at our ducted aircon packages or the brands we install. Or call 1300 101 100.
Good questions
Sizing questions
How accurate is this ducted sizing guide?
It is a rule of thumb, so treat it as a starting range, not a design. It does not see your roof space, window sizes, shading, ceiling insulation or how the house is laid out. Your free site inspection confirms the size, zones and outlets before we quote.
Why not just buy the biggest system?
An oversized system costs more to buy and run, and it can cool a room so quickly that it switches off before removing much humidity, which leaves rooms feeling clammy on the coast. Zoning often lets a smaller system cover the house well.
How many zones can I have?
Our standard ZoneTouch controller handles up to 6 zones. If you need more, or want a separate temperature in each zone, we can quote AirTouch 5. See smart controls and home automation.
Does a double-storey home need two systems?
Not always. Many double-storey homes run one system with ducts routed to the lower floor through a wall cavity or bulkhead; others suit two smaller systems. We decide at the inspection. See ducted air conditioning.
Do you design the system for new builds?
Yes. Send us your plans and we size and design the system from them, then install as the build progresses. See new builds and renovations.
Keep exploring
Related services and guides
Ducted aircon packages
Package configurations by brand, priced on quote.
Learn moreDucted air conditioning
How ducted systems work and how we install them.
Learn moreSmart controls and home automation
ZoneTouch and AirTouch 5 zone control.
Learn moreProper air duct design
Why the duct layout matters as much as the unit.
Learn moreReal words from real clients
Rated 5.0 from 292 Google reviews
Every review below is from our Google Business Profile. Read them all on Google.
5.0 from 292 Google reviews checked 13 Nov 2026- ★★★★★
Absolutely fantastic experience with Frost Solutions! I recently had a ducted air-conditioning system installed and honestly, from the very first conversation through to the finished installation, the whole process was seamless. ... The installation itself was done to a really high standard, the team worked efficiently and left everything clean and tidy. ... Great people, great communication, great workmanship and a great result.
Grant Google review, about Oct 2026
- ★★★★★
Couldn't recommend Frost Solutions highly enough. We recently had them install a 16kW Daikin ducted system with 8 outlets, 6 independent zones, AirTouch 5, multiple upgrades and a 5 year service plan. ... Another big positive is that Frost Solutions have their own electrical team as part of the installation. ... the entire experience was seamless.
Jordan Google review, about Sep 2026
- ★★★★★
Frost Solutions installed ducted air conditioning in my home today and I couldn't be happier. The team were professional, friendly, punctual, and down to earth. ... left the house spotless ... I also really appreciated the follow-up call from the office later in the day to check I was completely satisfied ... They're a local business with local staff, and the value was extremely competitive for the quality of service and workmanship provided.
Bradley Google review, about Nov 2025
- ★★★★★
Thanks guys For installing my Panasonic 18 kilowatt Ducted air conditioning today. The guys turned up on time and were very polite. They worked hard all day, did a great job and left the house neat and tidy. Also they were $2000 cheaper than the others. :)
Brett Google review, about Nov 2025
- ★★★★★
A massive thanks to Frost Solutions. We got a 16kw ducted system put in with 7 zones and 9 outlets. Tyrone and the team were super friendly and very professional doing an awesome job, even helping me to keep maximum space in our roof so I could do an attic room. They also decommissioned and removed 2 of our old split systems. Could not recommend them more highly.
Michael Google review, about Nov 2025
Your comfort, our priority.
Get it confirmed for free
We inspect your home, design the zones and outlets and send a fixed written quote.