Saleable area vs gross area in Hong Kong property
In Hong Kong property, the only measure that tells you how much indoor space you actually own is the saleable area (實用面積). Gross floor area (建築面積) — which used to be the standard — included a share of common areas, corridors, lift lobbies and sometimes even car parks, making two flats of the same listed “size” differ by hundreds of square feet of real living space. Since 2013, first-hand sales have been required by law to state only saleable area, but older resale listings and some agents still use gross floor area.
What is saleable area?
Under the Residential Properties (First-hand Sales) Ordinance (Cap. 621), the saleable area of a flat is measured from the exterior of its enclosing walls. If a wall is shared with a neighbouring flat, the measurement is taken from the middle of that wall. The area includes the floor space of the unit itself plus, if they exist, a balcony, utility platform or verandah — each measured from its own exterior walls.
Critically, the following ten items are excluded from saleable area even if they are physically part of your flat:
- air-conditioning plant room
- bay window
- cockloft
- flat roof
- garden
- parking space
- roof
- stairhood
- terrace
- yard
These must be stated separately in the sales brochure and price list. So if you see a flat advertised as “800 sq ft saleable”, that is the floor area you can walk on (including balcony/platform) — everything else is listed beside it, not hidden inside the number.
What was gross floor area and why was it banned from first-hand material?
Before the 2013 ordinance, developers routinely published a “gross floor area” for each flat, which added a pro-rata share of common parts: lifts, staircases, clubhouse, security rooms, pipe ducts, and sometimes even the car park. That meant two flats with the same gross floor area could have wildly different saleable areas. A flat with a large communal lobby or a superfluous plant room on its floor might appear the same size on paper as one with efficient design.
Since the ordinance took full effect, Sections 23(1) and 31(9) of Cap. 621 prohibit vendors from showing any area figure other than saleable area and the ten Schedule 2 items in sales brochures and price lists. You will not see a gross floor area in first-hand material at all. For resale flats, however, some listings still quote gross floor area; you must always ask which measure is being used.
Why the same number can mean very different homes
Imagine two resale flats both listed as “700 sq ft”. If one uses saleable area and the other uses gross floor area, the real difference can be more than 100 sq ft — roughly the size of an extra bedroom. A flat with a 700 sq ft gross area might have a saleable area of only 500 sq ft (depending on the building’s common area allocation). The advertised “size” tells you almost nothing until you know the measurement basis.
That is why the price-per-square-foot figure is meaningless without the area basis attached to it. A flat advertised at HK$15,000 per square foot of gross area is not the same price as HK$15,000 per square foot of saleable area — the latter buys you significantly more usable space. Always check the basis before comparing.
Efficiency ratio: the market term that is not a law
You may hear agents talk about the “efficiency ratio” (實用率) of a flat — their own calculation of saleable area divided by gross floor area. There is no official definition, no prescribed method, and no published figure from any government authority. The ratio is simply a rough guide to how much of a building’s total space (including common parts) ends up inside your flat. It is a market term only.
For first-hand projects, where no gross floor area is stated, you cannot compute a meaningful efficiency ratio from the developer’s materials. For resale flats, you can calculate it yourself if you have both figures: divide saleable area by gross area and multiply by 100. But remember, the gross area figure in a resale listing may itself use a different definition from the one used by the next agent. Comparison between buildings is unreliable.
A dedicated detail page covers efficiency ratio: how much of the flat you actually get — including how to look for hidden space that is excluded from saleable area but still useful, such as bay windows you can sit on or a large air-conditioning plant room.
How to read a modern floor plan
When you look at a first-hand sales brochure, the floor plan must clearly mark the saleable area, and separately show any bay window, balcony, utility platform, verandah, cockloft, flat roof, garden, parking space, roof, stairhood, terrace or yard that belongs to the unit. It will also show the internal dimensions of each room. The wall thickness — usually shown as a dashed or solid line — indicates whether the measurement goes to the middle of a shared partition or the full exterior for an external wall.
Our detail page on how saleable area is measured and what it includes walks through a sample floor plan, showing exactly where the measurement lines fall and which features count as floor area versus excluded space.
How to compare flats honestly
- Always confirm the area basis first. For first-hand sales, it must be saleable area by law. For resale, ask the agent or vendor: “Is this saleable area or gross floor area?” If they cannot tell you, walk away.
- Demand a breakdown. If saleable area is stated, ask for the separate areas of any balcony, utility platform or verandah. Those are not pure indoor space — they are open or semi-open. A flat with a large balcony may have a lower usable interior than one without.
- Ignore price per square foot unless the basis is uniform. If you are comparing two resale flats and each uses a different basis, convert them to saleable area before dividing by the price. A rough rule: if you only have the gross area number, assume a typical saleable proportion of 70–85% for a modern building, but verify with the actual saleable area figure from the vendor.
- Read the fine print. In a resale listing, the agent may bury the basis in tiny text. If you see “700 sq ft (approx)” with no qualifier, assume gross floor area and ask.
What to do next
Before you commit to any flat — first-hand or resale — contact the Sales of First-hand Residential Properties Authority (SRPA) to verify the current rules and any updated guidance on area disclosure. Their publications provide worked examples and the exact wording of the ordinance.
For a deeper dive, read the companion detail pages on how saleable area is measured and what it includes and on how to read a Hong Kong floor plan. Those will equip you to inspect a brochure or floor plan like a seasoned buyer.
You now know the one question to ask at every viewing: “Is that saleable or gross?” Get the answer in writing.