How much paint for a 4×5 m room (20 m²)
A 4×5 m room has 45.3 m² of walls excluding the door and window and 20 m² of ceiling. Below is how much paint each surface takes in two coats.
Walls
5tins
To buy
Needed: 12.5 l
2.5 l each = 12.5 l
Estimated leftover: 0 l
Thinner: Water (5–10 %). About 1 l for the whole volume.
What to buy
Water-based (acrylic) paint, 2.5 l can · 2.5 l each = 12.5 l5 pcs
Thinner: Water · 5–10 %1 l
Where this number comes from
45.3 m² × 2 coats ÷ 8 m²/l = 11.3 l, + 10% reserve = 12.5 l → 5 tins of 2.5 l (12.5 l).
Ceiling
3tins
To buy
Needed: 5.5 l
2.5 l each = 7.5 l
Estimated leftover: 2 l
Thinner: Water (5–10 %). About 0.44 l for the whole volume.
What to buy
Water-based (acrylic) paint, 2.5 l can · 2.5 l each = 7.5 l3 pcs
Thinner: Water · 5–10 %0.44 l
Where this number comes from
20 m² × 2 coats ÷ 8 m²/l = 5 l, + 10% reserve = 5.5 l → 3 tins of 2.5 l (7.5 l).
Paint: interior water-based
For walls and ceilings. In kitchens and bathrooms pick a washable one, scrub class 1–2 (EN 13300).
Tip from the trade
Apply the second coat perpendicular to the first and use paint from one batch — no streaks or colour differences.
How we calculated
Ceiling height 2.7 m, one door and one window. Water-based acrylic paint, coverage 8 m²/l, smooth substrate, 2 coats, 10% reserve, 2.5 l can.
If yours differs — open the calculator and change the dimensions, it will recalculate.