A standard HDB 4-room layout gives you roughly 90 sqm of internal floor area, packed into three bedrooms, two bathrooms, a living-dining strip, a kitchen and a service yard. It is the flat most Singaporean families buy, so the layout is worth reading like a balance sheet: every square metre you pay for should earn its keep. This guide walks the floor plan room by room with the dimensions HDB actually builds to, shows how a 2026 BTO 4-room differs from a 1980s one, and puts hard 2026 numbers on what a 4-room costs to buy and the income you need to qualify.
HDB classifies flats by the number of rooms, where a bedroom counts as a room and the living-dining area counts as one. So a 4-room flat is really three bedrooms plus a living-dining space. HDB's own brochures list the 4-room with an internal floor area of about 90 sqm, or roughly 94 sqm once you add the air-con ledge that sits outside the wall line.
Inside that footprint you get a master bedroom with an attached bathroom, two common bedrooms, a shared bathroom, a kitchen, a service yard and a household shelter (the reinforced store room that doubles as a civil-defence shelter). Newer BTO 4-rooms launched from the June 2026 exercise onward let you choose an open-kitchen layout or one with a partition wall, and ship without internal bedroom doors or floor finishes so you renovate from a cleaner slate.
Most modern 4-room plans run the living and dining as a single rectangle from the front door toward the service yard, with bedrooms clustered along one side. The numbers below are planning ballparks drawn from current BTO floor plans; your exact stack varies by a square metre or two, which is why HDB labels different stacks with slightly different areas in each project's price annex.
Treat these as the canvas you renovate against. The clearances matter more than the totals: a queen bed needs roughly 60-70 cm of walking space on the sides you use, and main walkways should keep about 60 cm clear, so a 9 sqm common bedroom fills up fast once a wardrobe goes in.
| Space | Typical area | What fits comfortably |
|---|---|---|
| Living + dining | 20-22 sqm | 3-seater sofa, TV console, 4-6 seat dining table |
| Master bedroom | 11-13 sqm | Queen bed, 2 bedside tables, wardrobe, small desk |
| Common bedroom (each) | 8-10 sqm | Single or super-single bed plus a wardrobe |
| Kitchen | 6-8 sqm | L-shaped run, fridge, hob, oven, some counter space |
| Service yard | 2-3 sqm | Washer, drying rack, bin |
| Bathrooms (each) | 3-4 sqm | Shower, WC, basin |
The single biggest layout decision in a 4-room is the kitchen. Newer BTO flats give you the choice up front; in a resale flat you can hack a wall to open it up, subject to HDB's renovation rules and a permit for any structural or wet-area work.
An open kitchen borrows the living-dining sightline so the flat feels larger and more social, which suits couples and families who cook lightly. A closed kitchen contains heat, oil and the smell of heavy wok cooking, which is why many households who cook Asian food daily keep the wall. There is no wrong answer, only a trade between perceived space and odour control.
If you are comparing a fresh BTO against a 1980s resale unit, the headline size gap is real but smaller than people assume. Many older 4-rooms land around 82-90 sqm depending on the model and era, while current BTO 4-rooms are standardised near 90 sqm internal. What changed more is the configuration: newer flats fold in the household shelter, an air-con ledge and a more efficient bedroom cluster.
Older flats sometimes reward you with quirks a new flat cannot match, like a more generous living room or a separate utility space, plus a mature-estate location near MRT and food. The trade-off is age. A flat with around 30 years left on its 99-year lease prices differently from a 95-year-lease BTO, and that remaining lease feeds straight into how much CPF you can use and what a bank will lend. Our cash-over-valuation note explains the cash gap that can appear on top of the valuation in a hot resale market.
Layout decides how you live; price decides whether you can. A 4-room is the value sweet spot of the HDB range, which is exactly why it is the most-balloted size. On the resale market, HDB's Resale Price Index reached 203.4 in Q1 2026, easing 0.1% from the previous quarter, the first time the index has cooled in years. The national median 4-room resale price sat near S$498,000 in Q1 2026, though mature estates run far higher: think well above S$700,000 in Queenstown or Bishan, while non-mature towns like Woodlands and Jurong West cluster around S$450,000 to S$520,000.
BTO is the cheaper door if you can wait for the build and meet the BTO eligibility rules. Buying new also brings you into the grant and loan framework cleanly: check what you can borrow with the HDB loan calculator before you commit, and pressure-test the monthly repayment against your income with the BTO affordability calculator. Note that DollarsAndSense's 2026 affordability piece uses a higher S$630,000 4-room benchmark and a 25-year, 1.6% loan to derive an income target near S$8,300 a month; we prefer to anchor on the HDB-reported median and to stress-test at today's higher loan rates, which is more honest for a buyer signing in 2026.
| Flat type | Internal floor area | Typical layout | Indicative resale median |
|---|---|---|---|
| 2-room Flexi | about 36-45 sqm | 1 bedroom, 1 bathroom | Lower (often leasehold-flexible) |
| 3-room | about 60-65 sqm | 2 bedrooms, 1-2 bathrooms | Around S$430,000-S$450,000 |
| 4-room | about 90 sqm | 3 bedrooms, 2 bathrooms | Around S$498,000 (national median, Q1 2026) |
| 5-room | about 110 sqm | 3 bedrooms + study/extra living, 2 bathrooms | Higher than 4-room |
| 3Gen | about 115 sqm | 4 bedrooms, 3 bathrooms (multi-gen) | Restricted to multi-gen families |
For an HDB housing loan, your monthly repayment cannot exceed 30% of gross monthly household income under the Mortgage Servicing Ratio, and there is an income ceiling of S$14,000 for a family buying a 4-room flat new from HDB. If you take a bank loan instead, the wider Total Debt Servicing Ratio caps all your debt at 55% of income.
A 90 sqm shell is forgiving if you plan the dead space first. The two common bedrooms are the rooms that strangle a family fastest, so decide early whether one becomes a study, a nursery or a guest room, because that changes whether you build wardrobes or leave the floor open. The service yard is the most under-used 3 sqm in the flat; a tall laundry cabinet there frees up the kitchen.
Budget the layout changes that need a permit (hacking the kitchen wall, moving a bathroom) separately from cosmetic work, since structural and wet-area jobs carry HDB conditions and cost more. If you are weighing buying new against buying old, our explainer on BTO vs resale lays out the timeline and total-cost trade-off, and the BTO renovation cost guide gives current 4-room renovation ranges.
A current HDB 4-room flat has an internal floor area of about 90 sqm, which is roughly 969 sqft, or around 94 sqm once you include the air-con ledge. Older 4-room flats from the 1970s-80s can be smaller, from about 82-84 sqm depending on the model.
A 4-room flat has three bedrooms: one master bedroom with an attached bathroom and two common bedrooms. It also has a shared bathroom, a kitchen, a service yard and a household shelter, so the name refers to three bedrooms plus the living-dining area counted as one room.
Choose an open kitchen if you want the flat to feel larger and you cook lightly, since it shares the living-dining sightline. Choose a closed kitchen if you cook heavy Asian food daily and want to contain heat, oil and smells. In a resale flat, hacking a wall to open the kitchen needs HDB approval.
Your home-loan repayment cannot exceed 30% of gross monthly household income under the Mortgage Servicing Ratio, and the income ceiling to buy a 4-room flat new from HDB is S$14,000 a month. The exact income you need depends on your price, loan tenure and the interest rate you lock in, so run the numbers in an affordability calculator before committing.
This is general financial information for Singapore, not personal financial advice. Figures change — verify current rates against the official sources above before acting. See our full disclaimer.