When you browse property listings in Hong Kong, you will see terms like gross floor area, saleable area, and carpet area. Among these, gross floor area (GFA) is the most consequential for developers, architects, and government planners, yet it is often misunderstood by individual buyers. GFA determines how large a building can be, how much land premium the developer must pay, and ultimately influences the saleable area you can use.
This article explains what gross floor area means under Hong Kong's Buildings Ordinance, how it differs from saleable area, and why you should care about it when evaluating a property. We will also look at recent changes to GFA concession rules that affect new developments.
What Is Gross Floor Area?
Gross floor area (GFA) is the total floor area within a building measured from the external walls. It includes every floor of the building, including basements, mezzanines, and roof structures. The Hong Kong Buildings Ordinance (Cap. 123) defines GFA in its Building (Planning) Regulations. The calculation excludes certain exempted items such as open balconies, staircases, lift shafts, and plant rooms, but includes all habitable and non-habitable spaces.
For a typical residential tower, GFA encompasses:
- All residential flats (including internal walls and external walls)
- Common areas like corridors, lobbies, and lift landings
- Clubhouse facilities, swimming pools, and gyms
- Car parking spaces and loading areas
- Plant rooms and refuse storage
- Fire escapes and staircases
Developers are limited by a maximum GFA allowed on a given site, which is expressed as a plot ratio. For example, a site with a plot ratio of 8.0 and a site area of 1,000 square metres can have a maximum GFA of 8,000 square metres. This cap is set by the government through the lease conditions and the Outline Zoning Plan (OZP).
How GFA Differs from Saleable Area
For a home buyer, the most relevant figure is usually the saleable area, which is the floor area you can actually occupy. Saleable area excludes common areas, external walls, and structural elements. The difference between GFA and saleable area can be substantial.
In a typical Hong Kong residential tower, the saleable area is roughly 70% to 80% of the GFA. The remaining 20% to 30% is taken up by common areas, structural walls, and building services. This ratio is called the efficiency ratio or the saleable-to-GFA ratio. For example, a flat with a GFA of 1,000 square feet might have a saleable area of only 750 square feet.
For a deeper comparison of these two figures, see our article Gross vs Saleable Area: Understanding the Difference.
When developers market a new project, they often advertise the saleable area because it is the usable space. However, the GFA is used to calculate the land premium paid to the government. The higher the GFA allowed, the more valuable the land. This is why developers push for maximum GFA concessions.
GFA Concessions: What Developers Can Exclude
The Hong Kong government allows developers to exclude certain building features from GFA calculations. These are called GFA concessions or exempted items. The rationale is to encourage developers to provide better amenities, greener buildings, and safer designs. Common GFA concessions include:
- Balconies and utility platforms
- Common corridors and lift lobbies
- Staircases and fire escapes
- Plant rooms and meter rooms
- Parking spaces and loading areas
- Clubhouse facilities and swimming pools
- Sky gardens and communal gardens
In recent years, the government has tightened these concessions. In 2022, the Development Bureau announced that from 2023 onwards, new residential developments would no longer be allowed to count certain facilities as GFA-exempt, including large clubhouses, swimming pools, and other recreational facilities. This change was intended to curb the trend of ever-larger clubhouses that inflated flat prices.
Before this change, developers could build extensive clubhouses with gyms, function rooms, and swimming pools without counting them toward the GFA cap. This allowed them to build more saleable flats while still offering luxurious amenities. After the change, these facilities count toward GFA, which means developers have less room for saleable area or must build smaller clubhouses.
For buyers, this means that new developments launched after 2023 may have smaller clubhouses or higher prices per square foot, as the developer recoups the lost GFA through higher flat prices. Alternatively, the efficiency ratio may improve because less space is wasted on non-saleable amenities.
How GFA Affects Property Value
GFA directly influences property value in several ways. First, the maximum GFA determines how many flats can be built on a site. A higher GFA means more flats, which can increase supply and potentially lower prices per flat. However, in Hong Kong, land supply is constrained, so higher GFA typically leads to higher land prices because developers can build more saleable area.
Second, GFA concessions affect the saleable area you get for your money. If a developer can exclude large common areas from GFA, they can build more saleable flats within the same GFA cap. This improves the efficiency ratio and gives buyers more usable space per dollar.
Third, changes in GFA rules can affect the value of existing properties. For example, if new developments after 2023 have smaller clubhouses, older developments with generous clubhouses may become more desirable. Conversely, if new developments have better efficiency ratios, older flats with lower efficiency may lose value.
When evaluating a property, always check the efficiency ratio. You can find this information in the sales brochure or from the property agent. A flat with a higher efficiency ratio (saleable area as a percentage of GFA) gives you more usable space. For resale flats, the efficiency ratio is often lower than new developments because building standards and GFA rules have changed over time.
To understand how to read a sales brochure and find these figures, read our guide Reading a Sales Brochure: Key Terms and Figures.
GFA and the Land Premium
When the government sells a land parcel, the land premium is calculated based on the maximum GFA allowed under the lease. The premium is essentially the price the developer pays for the right to build a certain amount of floor area. A higher GFA means a higher land premium.
For example, in the 2023 land sale for a residential site in Kai Tak, the winning bid of HK$12.8 billion was based on a maximum GFA of 500,000 square feet. That works out to a land cost of approximately HK$25,600 per square foot of GFA. The developer then adds construction costs, financing costs, and profit margin to arrive at the final selling price per square foot of saleable area.
Because land cost is a major component of flat prices, any change in GFA rules directly affects affordability. If the government reduces the maximum GFA on a site, the land premium drops, but the developer can build fewer flats. The price per flat may not decrease proportionally because fixed costs are spread over fewer units.
For a detailed overview of how property prices are determined, see How the Hong Kong Property Market Works.
GFA in the Context of Building Regulations
The Buildings Ordinance sets out specific rules for calculating GFA. The Building (Planning) Regulations define GFA as the area of every floor of a building measured from the external faces of the external walls. This includes:
- All floors, including basements and roof spaces
- Mezzanine floors and intermediate floors
- Staircases and lift shafts (counted once per floor)
- Corridors and lobbies
- Plant rooms and meter rooms
Excluded from GFA are:
- Open balconies (but covered balconies may be included)
- Open-sided covered walkways
- Fire escapes and staircases that are open to the sky
- Certain green features like sky gardens and communal gardens (subject to approval)
These exclusions are important because they allow developers to add value without consuming GFA. For example, a balcony that is open on one side may be exempt, allowing the developer to offer outdoor space without reducing the number of flats they can build. However, recent rule changes have limited these exemptions.
In 2018, the Buildings Department revised its practice notes to tighten the definition of GFA exemptions for green features. Developers could no longer claim exemptions for items like large planters or extensive green roofs unless they met strict criteria. This reduced the total GFA available for saleable flats and increased construction costs.
How to Use GFA When Comparing Properties
When comparing two properties, GFA gives you a baseline for density and scale. A building with a higher GFA per site area (higher plot ratio) is denser, which may mean more neighbours, less privacy, and more competition for lifts. However, it also means more facilities and potentially lower prices per square foot because the land cost is spread over more area.
For individual flats, you should focus on the saleable area rather than GFA. But GFA can help you understand the efficiency of the flat. If two flats have the same saleable area but different GFA, the one with the lower GFA is more efficient. That means the developer wasted less space on common areas and walls.
To calculate efficiency ratio, divide the saleable area by the GFA and multiply by 100. For example:
- Flat A: Saleable area 800 sq ft, GFA 1,100 sq ft. Efficiency = 72.7%.
- Flat B: Saleable area 800 sq ft, GFA 1,050 sq ft. Efficiency = 76.2%.
Flat B is more efficient. You get the same usable space but pay for less common area. In Hong Kong, efficiency ratios for new developments typically range from 70% to 80%. Older buildings from the 1970s and 1980s often have lower efficiency ratios, sometimes below 65%, because building standards required thicker walls and larger common areas.
For more on how to evaluate floor plans, see Understanding Floor Plans: A Buyer's Guide.
Recent Changes and Controversies
The GFA concession system has been controversial. Critics argue that developers have abused concessions to build oversized clubhouses and luxury amenities that drive up flat prices. In response, the government announced in 2022 that from 2023 onward, new residential developments would no longer be able to claim GFA exemptions for recreational facilities such as swimming pools, gyms, and function rooms. These facilities must now be counted as GFA, which reduces the space available for saleable flats or forces developers to build smaller clubhouses.
This change has significant implications. For buyers, it means that new flats after 2023 may have smaller common areas and fewer amenities. However, it may also lead to lower flat prices because developers cannot add as much value through luxury facilities. The net effect is still being debated.
Another controversy is the use of GFA to calculate land premiums. Some developers have argued that the government's method of calculating GFA for premium purposes is inconsistent with the Buildings Ordinance, leading to disputes. In 2023, the Court of Final Appeal ruled in favour of the government in a case involving a large development in Tseung Kwan O, confirming that the government's method was correct.
For buyers, these legal and regulatory changes mean that the GFA of a new development may be calculated differently than in the past. Always check the date of the building plan and the applicable GFA rules when comparing new and older developments.
GFA and Mortgage Considerations
Banks in Hong Kong use the saleable area, not GFA, to determine the property's value for mortgage purposes. However, GFA can indirectly affect your mortgage because it influences the property's market value. A property with a low efficiency ratio (high GFA relative to saleable area) may be less attractive to buyers, which could lower its resale value and affect the loan-to-value ratio.
When applying for a mortgage, the bank will send a valuer to assess the property. The valuer will consider the saleable area, location, age, and condition. If the building has a very low efficiency ratio, the valuer may discount the value, leading to a lower mortgage amount. You may need a larger down payment.
For a detailed explanation of mortgage stress testing and affordability, read Stress Testing Explained: How Banks Assess Your Loan.
Similarly, the management fee is often calculated based on GFA or saleable area, depending on the building's management agreement. Some buildings charge fees based on GFA, which means you pay for common areas you cannot use. Check the management fee structure before buying.
For more on recurring costs, see Management Fees and Other Recurring Costs.
Practical Tips for Buyers
When you are evaluating a property, follow these steps to use GFA effectively:
- Ask the agent or seller for both the GFA and the saleable area. In Hong Kong, these figures must be disclosed in the sales brochure for new developments. For resale flats, you can find them in the land registry records or the original sale and purchase agreement.
- Calculate the efficiency ratio. Divide saleable area by GFA. If the ratio is below 70%, ask why. Older buildings may have lower ratios, but new buildings should be above 75%.
- Compare the efficiency ratio across similar properties in the same area. A higher ratio means you get more usable space for your money.
- Check the building's age and the GFA rules at the time of construction. Buildings built before 2000 may have different concession rules than newer ones.
- If you are buying a new development, ask the developer for a breakdown of GFA concessions. This will show you how much space is allocated to common areas and amenities.
Understanding GFA gives you a clearer picture of what you are buying. It helps you compare properties objectively and avoid paying for space you cannot use.
For a step-by-step guide to the entire buying process, see Step by Step Buying Process in Hong Kong.