Apartment size in China: 建筑面积, 套内面积, and 公摊
Last reviewed: 2026-05-24
Reader intent: Decode how Chinese property is measured, so the family can compare China apartments to home-country apartments correctly, evaluate the real usable space for a retired parent, and avoid the most common mistake (paying for hallway and elevator allocation rather than livable floor area).
Plain-English answer: In mainland China, an apartment’s advertised size usually quotes 建筑面积 (jiànzhù miànjī, gross construction area). That number includes the apartment’s internal construction footprint plus a share of common building areas, known as 公摊 (gōng tān, shared/common allocation). A “100 sqm” apartment in China commonly delivers 70 to 80 sqm of actual usable internal space; a 100 sqm apartment in Sydney or Toronto delivers more like 90 to 95 sqm. Compare like-to-like, or you will systematically overestimate what a Chinese apartment offers.
The core terms a family must understand
| Chinese term | Pinyin | Rough English meaning | Why it matters |
|---|---|---|---|
| 建筑面积 | jiànzhù miànjī | Gross construction area, often “saleable area” | Usually the headline number in listings and sales contracts; includes 公摊 |
| 套内建筑面积 | tàonèi jiànzhù miànjī | In-unit construction area | The apartment itself, but still includes internal and external wall thicknesses |
| 套内使用面积 | tàonèi shǐyòng miànjī | Usable internal floor area | Closest to what a retiree experiences as livable space, walls subtracted |
| 公摊面积 | gōng tān miànjī | Allocated common construction area | Elevators, corridors, lobbies, stairs, equipment rooms, allocated across all units in the building |
| 公摊比例 | gōng tān bǐlì | Common-area ratio | Percentage of headline area that is shared allocation; typical 15 to 30% |
| 得房率 | dé fáng lǜ | Efficiency ratio | Percentage of headline area that is inside the unit; typical 70 to 85% |
| 公摊系数 | gōng tān xìshù | Common-area coefficient | Multiplier used in the technical calculation; rarely shown to buyers |
| 阳台 | yáng tái | Balcony | Counted as half-area in most cities (enclosed) or quarter-area (open) |
| 飘窗 | piāo chuāng | Bay window | Sometimes counted in 建筑面积, varies by city and developer |
| 设备平台 | shèbèi píngtái | Equipment platform | Sometimes counted; check the contract |
How the headline number lies (or rather, defines a different reality)
If a listing says:
- 建筑面积: 100 sqm
- 得房率: 75%
Then the apartment delivers roughly 75 sqm of in-unit floor area. After internal wall thickness, that becomes about 68 to 72 sqm of truly walkable, furnish-able space. The remaining 25 sqm is the parent’s allocated share of the building’s hallways, lobby, elevators, stairwells, and mechanical rooms. The parent pays for it, the parent pays property fees on it, but the parent does not live in it.
This is not necessarily mislisting. It is being measured under a Chinese convention that the rest of the world does not use. The apartment listing is technically accurate under PRC measurement rules; the family’s mental model of what “100 square metres” means is foreign-trained.
For comparison reference points:
| Headline area | Typical 得房率 by building type | In-unit floor area | Usable furnishable area |
|---|---|---|---|
| 80 sqm | 75% (mid-rise compound) | ~60 sqm | ~55 sqm |
| 100 sqm | 75% (mid-rise compound) | ~75 sqm | ~68 sqm |
| 100 sqm | 70% (high-rise tower with many lifts) | ~70 sqm | ~63 sqm |
| 100 sqm | 85% (low-rise walk-up, fewer common areas) | ~85 sqm | ~77 sqm |
| 120 sqm | 75% | ~90 sqm | ~82 sqm |
| 150 sqm | 75% | ~113 sqm | ~102 sqm |
A retired parent’s mental anchor of “I want a 100 sqm apartment, similar to my Sydney unit” translates to needing something more like a 120 to 130 sqm listed Chinese apartment.
Why Western comparisons break (and how to fix them)
Western buyers and renters compare homes using internal living area, usable square footage, or familiar floor-plan norms (CMA in Canada, RICS in the UK, REIA in Australia all roughly measure internal usable space). Mainland Chinese listings emphasise 建筑面积. The result: a family from Toronto sees “100 sqm, CNY 12,000 per sqm” and assumes the same scale as their Toronto condo.
This creates predictable bad comparisons:
| Misleading comparison | Better comparison |
|---|---|
| ”This 100 sqm China apartment is much cheaper than a 100 sqm Toronto condo." | "What is the 套内使用面积? What is the layout efficiency? What is the lift access? What is the monthly 物业费?" |
| "This place is only CNY 12,000 per sqm." | "CNY 12,000 per sqm of what measurement? What does the in-unit area cost? What does the usable area cost?" |
| "The apartment has three bedrooms." | "Can the parent move safely through the rooms, bathroom, kitchen, and entry with a walker if needed?" |
| "It’s a great deal compared to Sydney." | "What is the equivalent in Sydney-measurement terms? What does the total cost of ownership look like over 10 years including 物业费 and renovation?” |
The translation rule of thumb for a diaspora family: multiply the Chinese 建筑面积 by 0.70 to 0.75 to get a roughly comparable home-country usable-area figure. Then compare apartment-to-apartment.
What official rules say
China’s 商品房销售管理办法 (Measures for the Administration of Commercial Housing Sales) defines commodity-housing construction area as 套内建筑面积 plus allocated shared and common construction area. The regulation also says that if housing is priced by unit or by in-unit construction area, the contract should state both the construction area and the allocated shared and common area.
In 2024, several local authorities (Hangzhou, Suzhou, Changsha, others) began promoting pricing by 套内 area as the headline figure, recognising the consumer confusion the headline 建筑面积 creates. This is a slow transition; most listings still default to 建筑面积. The sales contract is the binding document and will specify both figures.
Local explanations, such as Wuhan housing authority guidance, describe property-right area as consisting of in-unit construction area plus allocated common construction area. Common areas may include stairs, elevators, corridors, lobbies, equipment rooms, pipe wells, and related shared building space. The detailed breakdown is in the building’s 测绘报告 (cèhuì bàogào, surveying and mapping report), which the developer or property management can produce on request.
What matters for a retired parent (and what does not)
Retirees should care less about headline square metres and more about usable comfort and safe daily-living capacity:
- Can the parent use a walker inside the apartment if needed in 5, 10 years?
- Is the bathroom safe and accessible? Door width, shower threshold, grab-bar mounting points?
- Is the kitchen usable for the parent or for a helper preparing meals?
- Is there space for a caregiver, a 陪诊, or an adult child to stay overnight?
- Are bedrooms large enough after wardrobes and beds to allow comfortable movement?
- Is the elevator reliable, with backup power for outages?
- Are corridors, lobby, and entry step-free or step-minimised?
- Is the apartment damp, noisy, or badly ventilated? Chinese tier-1 cities with high humidity (Guangzhou, Shanghai, Xiamen) make this a year-round concern.
- Is the orientation southern (preferred for sun and warmth in winter)?
- How loud are the neighbours, the corridor, the elevator shaft, the street, the construction next door?
A small efficient layout in a well-built compound beats a large inefficient layout in a low-quality compound, every time.
Checklist before renting or buying
Ask for, in writing:
- 建筑面积 (gross construction area)
- 套内建筑面积 (in-unit construction area)
- 套内使用面积 if available (usable internal floor area)
- 公摊面积 or 公摊比例 (allocated common area or ratio)
- Floor plan with dimensions, including all room measurements
- Live video walkthrough or in-person inspection
- Bathroom and kitchen measurements (door width, internal floor, fixture locations)
- Elevator count, maintenance condition, backup power
- 物业费 (property management fee per sqm per month), heating and cooling cost estimates, parking, maintenance fund contributions
- Building age, total floors, units per floor, total units in the compound
During an in-person viewing, measure:
- Front door width and clear passage width
- Bathroom doorway, internal floor, shower threshold
- Shower area; can a chair fit?
- Hallway width; can a walker pass?
- Bed-to-wall clearance in main bedroom
- Kitchen turning space; can two people pass?
- Step thresholds at balcony, entry, bathroom
- Balcony safety; railing height, drainage, weight tolerance
- Window operation; can the parent open and close them safely?
- Light switch locations; are they reachable from bed and from the door?
Note: the cheap pocket laser measure (CNY 80 to CNY 200) is the single most useful tool for an apartment viewing. The agent will look surprised; use it anyway.
Red flags
- The agent only repeats headline 建筑面积 and cannot quote 套内使用面积 or 得房率
- No one can explain 套内 vs 公摊 in plain Mandarin
- The floor plan has long corridors and wasted entry vestibules
- The building has few elevators for many units (e.g. two lifts serving 30 floors of 8 units each)
- The apartment is advertised as “large” but feels cramped on viewing
- The compound has impressive lobbies and external landscaping but poor in-unit layout (often a sign of 公摊 over-allocation)
- 物业费 is unusually low (under CNY 1.50 per sqm per month for a high-rise) suggesting deferred maintenance
- The 测绘报告 cannot be produced
- The seller or agent resists in-person measurement during viewing
Property due-diligence beyond the floor plan
The family should also verify, in person if possible:
- Visit the building in rain, at night, on a weekday afternoon, and during peak lift-use hours (7:30 to 8:30 am, 6:30 to 7:30 pm)
- Talk to current residents in the lobby or at the wet market nearby; ask about property management responsiveness, lift breakdowns, leaks, damp, heating, parking, community disputes, whether older residents live there year-round
- If buying, verify foreign-passport purchase eligibility for the specific city (see rent-before-buying deep page); some cities restrict foreign-passport purchases by visa type and length of stay
- Verify funds transfer, tax implications, title cleanliness, marital-property and inheritance issues with a local property lawyer before committing
- Confirm rental registration support and landlord or developer cooperation if renting
Common mistakes
- Comparing China headline area to home-country usable area. Always translate first: multiply Chinese 建筑面积 by 0.70 to 0.75 for a rough comparison.
- Trusting the agent’s verbal assurance. The 得房率 and 公摊 are in the 测绘报告 and the sales contract; ask for both in writing.
- Choosing the largest unit available. Larger units cost more to heat, cool, clean, and work through; not better for a retiree.
- Falling in love with the lobby. A grand lobby is paid for via 公摊. The parent does not live in the lobby.
- Skipping the in-person measurement. Door widths and bathroom clearances determine whether the apartment is usable in 5 years if mobility declines.
- Buying before renting. See the rent-before-buying deep page; the trial period catches issues that a video walkthrough cannot.
- Assuming all balconies and bay windows are counted the same. Conventions vary by city; check the contract.
- Ignoring 物业费 in the cost projection. Over a 20-year holding period, 物业费 at CNY 5 per sqm per month on a 120 sqm apartment compounds to CNY 144,000 of fees alone. Factor this in.
What to verify locally
- The target city’s standard pricing convention (still 建筑面积 in most cities, transitioning to 套内 in some)
- Foreign-passport eligibility to purchase in the target city by visa type and length of stay
- 物业费 standard for the building type (mid-rise compound, high-rise tower, low-rise walk-up)
- Whether the developer or property management can produce the 测绘报告 on request
- Whether the local agent is licensed (look for 房地产经纪人 certification) and represents the buyer or the seller
- Property tax pilot status in the target city (Shanghai, Chongqing have variants; expansion possible)
- Heating system (central vs individual) and its cost implications in the parent’s target apartment
Sources
| Source | Why it matters | URL | Last verified |
|---|---|---|---|
| 商品房销售管理办法 (Measures for the Administration of Commercial Housing Sales) | Defines the gross area and in-unit area distinction | https://www.gov.cn/zhengce/2022-01/25/content_5712037.htm | 2026-03 |
| Wuhan housing authority explanation of in-unit construction area and allocated common construction area | Operational reference for area calculation | https://zgj.wuhan.gov.cn/xxgk/zcfgyjd_1/zcwd/202204/t20220415_1956582.shtml | 2026-03 |
| People.cn coverage of cities transitioning to 套内 pricing (Dec 2024) | Tracks the policy shift | https://finance.people.com.cn/n1/2024/1221/c1004-40386798.html | 2026-03 |
| Shanghai government foreigner home-purchase guidance | Foreign-passport purchase eligibility for Shanghai | https://english.shanghai.gov.cn/en-PurchaseaHouse/20231215/748213599b42410f9118e531914f8bf0.html | 2026-03 |
| Beijing foreign individual housing purchase policy example | Foreign-passport purchase eligibility for Beijing | https://english.beijing.gov.cn/government/policytoolkittwo/INV_Policy_Text/202408/t20240815_3774599.html | 2026-03 |
| 商品房销售面积计算及公用建筑面积分摊规则 (rules for sales area calculation and common area allocation) | Technical basis for the calculations | China government portal | 2026-03 |
Editorial warning: This is planning information, not property or legal advice. Always engage a licensed local property lawyer and a buyer-side agent before committing to a Chinese property purchase. Foreign-passport purchase rules vary by city and change without notice.