Compact is the default in Japanese city housing. A typical Tokyo or Osaka apartment fits a full life into a footprint that would hold one generous living room elsewhere, and it manages that by being planned rather than roomy: a factory-built bath module, a system kitchen sold in fixed widths, sliding-door closets instead of dressing rooms, and a balcony that does the work of a utility room. Renovation in that setting is less about creating space than about measuring what exists and choosing exactly what goes into it.
This guide covers the layout codes, how to measure a small flat precisely enough to order from, how the oshiire closet and the unit bath shape any plan, what sizes compact kitchens and appliances come in, and how to run the site’s calculators in rooms where every centimetre is doing a job.
Read the layout code digit-first: 1R is one room with the kitchen in it; 1K adds a separate kitchen room; 1DK a dining-kitchen; 1LDK a living-dining-kitchen plus a bedroom; 2LDK two bedrooms. The digit counts rooms besides the kitchen area. A unit bath is a factory-built module with fixed footprints — you plan around it, not through it. Measure in millimetres, at several heights, before ordering anything, and let the measured sketch — not the code — drive every quantity.
The Layout Codes: 1R to 2LDK
Japanese listings name a floor plan with a digit and up to three letters. The letters are the vocabulary: R means one combined room, K a separate kitchen, D a dining space, L a living space. The digit counts the rooms besides the kitchen — so a 2LDK is two bedrooms plus one living-dining-kitchen, and a 1R is a studio where the kitchen sits in a corner of the single room. The system reads from small to large:
| Code | How to read it | Typical form | Commonly quoted area |
|---|---|---|---|
| 1R | one room, kitchen in the corner | studio | ≈ 13–25 m2 |
| 1K | one room plus separate kitchen | studio with a kitchen room | ≈ 18–30 m2 |
| 1DK | one room plus dining-kitchen | kitchen that seats a table | ≈ 25–40 m2 |
| 1LDK | one bedroom plus living-dining-kitchen | one-bedroom flat | ≈ 30–50 m2 |
| 2LDK | two bedrooms plus living-dining-kitchen | two-bedroom family flat | ≈ 45–70 m2 |
Those areas are broad ranges from city listings, not standards — nothing fixes a 1K at any particular size, and two flats carrying the same code can differ by ten square metres. There is a comparison trap as well: quoted areas are commonly the exclusive area (senū menseki), measured to the centre line of shared walls and excluding corridors and lift lobbies. The code tells you the layout; only the floor plan and a tape measure tell you the size. Rooms may still be described in tatami mat counts — see Tatami Mats and Room Sizes for that system.
Measuring a Small Flat: Every Centimetre Counts
A compact flat has no slack to absorb a measuring error. Fitted work is planned to the millimetre, because the slots — appliance bays, kitchen runs, closet openings — are tighter than the rooms around them. A 600 mm (23.6 in) space for a washing machine is not 600 mm once a door frame, a skirting board or the maker’s stated ventilation gap is subtracted.
The practical routine: measure every wall at skirting, waist and ceiling height — older flats drift out of square — and record the smallest figure wherever something must fit flush. Sketch each room, marking door swings, windows, the air-conditioner pipework penetration, drains, gas points and the distribution board. Before anything large is ordered, measure the lift interior and the stairwell too; in older mansion blocks the lift is often the tightest dimension a delivery has to pass. A laser measure plus one tape covers a small flat in an hour, and that single sketch then feeds every calculator on this site.
The Oshiire: The Closet Is the Storage Plan
The oshiire (押入れ) is the two-compartment sliding-door closet that anchors a Japanese bedroom: a lower bay for the futon, an upper shelf bay above it, the whole thing commonly about 800–900 mm (31–35 in) deep — sized to swallow a folded futon. In many compact flats it is the majority of the home’s storage, so it belongs in the renovation plan on day one rather than as an afterthought.
Two planning rules of thumb: keep it, or replace it with full-height storage of equal or greater volume — scattered low units rarely recoup what an oshiire holds, and the ceiling height in flats (commonly around 2,200–2,400 mm) is worth using to the top. Measure the inside width at several points, and note that the sliding doors overlap the opening by their frame width. If the room is a tatami room, keep the path between the oshiire and the sleeping floor clear — the futon comes out at night and goes back in the morning.
Unit Baths: Fixed Modules, Not Free Design
The bathroom in most Japanese flats is a unit bath (also sold as a system bath): a factory-built floor, wall and ceiling shell delivered as one module and set into a structural shaft. Makers offer a menu of discrete footprints — compact units near 1,100 × 1,400 mm in older flats, with 1,210 × 1,600 mm and 1,210 × 1,700 mm among the common newer sizes, and larger modules above them. You choose from the menu; you do not specify an arbitrary size.
That constrains renovation in two ways. First, a bigger module only goes in if the shaft, the drain position and the door position allow it — “just moving the wall” is not how a unit bath grows. Second, the inside of the module is finished panels, not a tiling substrate: decorative tile work belongs on the walls outside the unit. When you survey, record the module’s printed size — usually on a label in the door frame — rather than assuming the interior measurement is the ordering dimension.
Compact Kitchens and Appliances
System kitchens are sold as modular runs in fixed widths — 1,800, 2,400 and 2,550 mm are typical listing widths — with counter depths around 600 mm and slimmer lines for narrow galley layouts. A two-burner hob and a single sink are standard at the compact end, and the under-counter space is sized for built-in appliances. The planning move is to measure the run wall to wall and then match the module, not to expect a module to be trimmed to the wall.
Appliances follow the same logic. Compact washing machines are commonly 500–600 mm (20–24 in) wide, and slim refrigerators around 550–600 mm. But the slot, not the box, is what you measure: makers state installation clearances for ventilation and door swing, and the stated gap plus the box is the real footprint. In older blocks, check the lift interior against the appliance before ordering — units that do not fit the lift go up the stairs, or do not arrive at all.
The Balcony as a Semi-Outdoor Room
Most flats have one balcony, commonly about 1.0–1.5 m deep, and it works as the semi-outdoor room: a drying rack for laundry is close to universal, and plants, bicycles and shoe storage all migrate there. Balconies are usually exclusive-use common space rather than part of the quoted dwelling area, and the rules on what may go on them vary by building and its management association — some allow storage, some allow very little, and in many buildings an emergency descent hatch must be kept clear. Check the building’s rules before planning the balcony as anything in particular.
Lighting and Storage in Small Rooms
Small rooms punish over-furnishing and reward one strong decision. For lighting, flats commonly have a single ceiling point per room and shallow ceiling voids — often concrete slab directly behind the finish — so recessed downlights are frequently off the table and surface-mounted fittings do the work. Choose them by the room’s area rather than by eye: the Lighting Calculator converts room size into a lumen target, which keeps a 6-mat bedroom from being lit like a workshop. For storage, full-height built-ins on one wall beat scattered units — they use the full wall height instead of the 1,800 mm a chest of drawers reaches — and sliding doors suit narrow rooms because they claim no swing space.
Running the Calculators in a Compact Flat
Three calculators do most of the renovation planning, and all three feed from the same measured sketch:
- Paint Calculator — enter each wall’s length and height and subtract openings. Per-wall measurement beats any rule of thumb in rooms this size, and the calculator returns litres per coat for the coverage printed on the paint’s label.
- Flooring Quantity Calculator — room dimensions plus plank or tile size in; area, material count and waste allowance out. If a tatami room is being converted, measure wall to wall rather than working from the mat count.
- Wallpaper Calculator — wall dimensions and the roll size printed on the label in; rolls needed out, with the pattern repeat accounted for.
Measure once, in millimetres, and every tool has what it needs. For wet-area re-tiling outside the unit bath, Tile Spacing and Grout Joints covers the joint decisions that follow.
Common Mistakes
- Reading the code as a size. 1K describes a layout; two 1K flats can differ by 10 m2.
- Measuring once, at one height. Walls drift out of square; fitted work wants the smallest figure.
- Designing the bathroom free-form. Unit baths are fixed modules — plan from the maker’s menu and the shaft, not from a sketch of an ideal room.
- Ordering appliances by box width. The real slot is the box plus stated ventilation gaps plus door swing.
- Assuming the balcony is yours to use freely. Rules vary by building; check the management association’s rules before planning around it.
Plan It With the Calculators
Measure the rooms, then let the Flooring Quantity Calculator do the arithmetic: room dimensions and plank or tile size in, area and material count out, waste allowance included. The same measured sketch sizes the paint, wallpaper and flooring orders — make it once, in millimetres, and reuse it.
Frequently Asked Questions
What does 1LDK mean?
One bedroom plus a combined living-dining-kitchen. The digit counts rooms besides the kitchen area: 2LDK is two bedrooms plus the same LDK, 1DK is a single room plus a dining-kitchen, 1K is a room plus a small separate kitchen, and 1R is a studio with the kitchen in the room. The code describes the layout, not the floor area.
Can a unit bath be made bigger during a renovation?
Only within the maker’s module menu, and only if the structural shaft, drain position and door position allow it. Unit baths are factory-built shells in fixed footprints — commonly around 1,210 × 1,600 mm or 1,210 × 1,700 mm in newer flats — and their finished panel walls are not designed to be tiled over, so decorative work happens outside the module.
How deep is an oshiire closet?
Commonly around 800–900 mm, sized to take a folded futon, with a fixed shelf dividing the lower bay from the upper. Measure the inside width at several points when planning storage or replacements — the sliding-door frames overlap the opening.
Are balconies included in a flat’s quoted floor area?
Usually not. Balconies are commonly exclusive-use common space, excluded from the dwelling’s quoted exclusive area. Rules on what may go on them vary by building and management association — drying racks are near-universal, but storage and other uses are often restricted, and emergency hatches must stay clear.
Related MyHouseLogic Guides
- Tatami Mats and Room Sizes — rooms counted in mats, and how to convert the count to square metres.
- Tile Spacing and Grout Joints — joint widths and grout maths for wet-area re-tiling.
- Flooring Quantity Guide — turning a measured room into a plank and board order with waste.
- Homes Around the World — the collection of regional measurement and planning guides.
- Field Guide library — every MyHouseLogic guide, each tied to a calculator.
The bottom line: a compact Japanese home is a set of codes and modules — 1R to 2LDK for the plan, fixed footprints for the bath, fixed widths for the kitchen. Read the code for the layout, measure in millimetres for the reality, and plan around the modules rather than through them.