How much paint do I need for a whole home?
A home has roughly twice its floor area in wall area. An 80 sq m flat typically needs 40-55 litres of wall paint, 14-20 litres of ceiling paint and 8-11 litres of wood paint.
Short answer: an ordinary home with a 2.50 m ceiling has roughly twice its floor area in net wall area, because the internal partition walls count on both sides. An 80 sq m flat therefore has around 160 sq m of wall and needs, for two coats, 40-55 litres of wall paint, 14-20 litres of ceiling paint and 8-11 litres of wood paint for doors, frames and skirting. The factor is a rough guide for shopping — the precise figure needs the perimeter of every room measured.
Why the wall area is double the floor area
People almost always guess too low when a whole home needs painting, and the reason is the internal walls. A partition wall between a bedroom and a living room is two surfaces that both need painting, but it takes up almost no floor area. The more rooms a home is divided into, the more wall per square metre of floor.
So the factor holds at roughly 2 times the floor area for a normal, subdivided home with a 2.50 m ceiling — ranging from around 1.8 for an open, single-storey home with few partitions, up to 2.5 for a flat with many small rooms and long corridors. If the ceiling is 2.80 or 3.20 m, as in many older apartment blocks, scale the factor up accordingly: a 3.00 m ceiling gives 20% more wall than a 2.50 m one.
The example: an 80 sq m flat
The flat has a living room, a bedroom, a study, a kitchen, a bathroom and a hallway. Worked out room by room, with gross wall minus doors and windows:
- Living room, 5.0 × 5.0 m: perimeter 20.0 m × 2.50 = 50 sq m gross, minus about 6 sq m of windows and doors = 44 sq m.
- Bedroom, 4.0 × 3.5 m: perimeter 15.0 m × 2.50 = 37.5 sq m, minus 4 sq m = 33.5 sq m.
- Study, 3.5 × 2.9 m: perimeter 12.8 m × 2.50 = 32 sq m, minus 4 sq m = 28 sq m.
- Kitchen, 3.5 × 2.6 m: 30.5 sq m gross, minus openings and the surfaces covered by cabinets and tiles = about 16 sq m.
- Bathroom, 2.2 × 2.3 m: 22.5 sq m gross — but this is often tiled or covered in wet-room paint, so calculate it separately, or leave it out of the sum.
- Hallway and entrance, 4.0 × 2.0 m: 30 sq m gross, minus five doorways at about 9 sq m = 21 sq m.
Total without the bathroom: about 143 sq m. With the bathroom painted: about 162 sq m. That's 1.8-2.0 times the floor area — the low end of the factor, because the kitchen and bathroom have large surfaces covered by cabinets and tiles.
From square metres to litres
The quantity is a division: area × number of coats ÷ coverage. The coverage is printed on the tin.
Walls: 160 sq m × 2 coats = 320 sq m of painted surface. At 6-8 sq m per litre per coat: 320 ÷ 8 = 40 litres, 320 ÷ 6 = 53 litres. Add wastage: 40-55 litres. Buy four to six 10-litre tins.
Ceilings: the ceiling area is the rooms' floor area, and the six rooms in the example add up to 71 sq m of floor — less than the 80 sq m of floor area, because floor area also includes the walls. Two coats = 142 sq m. At 7-10 sq m per litre: 14-20 litres of ceiling paint.
Woodwork: six doors with frames at about 5.1 sq m each = 31 sq m, plus skirting — around 60 running metres at 0.135 sq m each = 8 sq m — plus window sashes and frames, say 6 sq m. Total about 45 sq m × 2 coats = 90 sq m. At 8-12 sq m per litre: 8-11 litres of wood paint.
What the materials add up to against the job
Wall paint is by far the biggest item, because it takes the most litres: 40-55 litres against 14-20 litres of ceiling paint and under ten litres of wood paint. Wood paint, on the other hand, is the most expensive per litre, so it looms larger in the bill than the litre count suggests.
The materials for a whole 80 sq m flat are a small line item compared with what the labour costs if a painter does the work. That's worth keeping in mind when choosing between painting it yourself and having it done: the difference between the two is hours, not paint. If a painter is doing the work, get two or three quotes on exactly the same written scope — that's the only way to compare them fairly.
Buying right for a whole home
- Buy it all in one tinting batch. Two tins of white paint tinted in separate batches can differ visibly. If you need 45 litres, order it as one purchase.
- Buy in large tins. A 10-litre tin costs noticeably less per litre than four 2.5-litre tins of the same paint. Same quantity, different price — and one less tin to stir.
- Mix the tins. Pour two tins into one large container and stir before starting a big wall. That keeps the colour consistent all the way across.
- Paint room by room, not coat by coat across the whole home. One finished room a day is easier to live with than a whole flat with just one coat on.
- Keep the leftovers. Half a litre per colour, labelled with room and date, is worth its weight in gold two years from now when a shelf bracket needs a touch-up.
How to get the real square metres instead of a factor
The "floor area × 2" factor is a rough guide for deciding whether to bring home 20 or 50 litres. If the figure is going into a purchase or a quote, the rooms' perimeters need to be measured — and that's where the mistakes happen: recesses, chimney breasts, bays and skewed corners.
HouseSense works out the wall area from the home's own geometry, room by room, with doors and windows subtracted. The home is scanned with the iPhone's LiDAR or drawn on graph paper in the app, and the takeoff can be exported as a PDF if a painter needs to quote on the same basis you've calculated on.
The sum itself doesn't change: net wall area × number of coats ÷ coverage + wastage. It applies to one room and to a whole home alike.