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Estimate paint in litres or gallons from room dimensions, coats and coverage, subtracting doors and windows — works for interior emulsion and exterior weather coats.
Construction
Generated on May 23, 2026
NaN liters for NaN m² paintable area
Paint Required
NaN liters
Formula
Wall area = 2·(W + L)·H. Paint liters = paintable × coats ÷ coverage.
Estimate paint in litres or gallons from room dimensions, coats and coverage, subtracting doors and windows — works for interior emulsion and exterior weather coats.
A paint calculator estimates how much paint you need to cover the walls of a room, taking into account the room's dimensions, the number of doors and windows to subtract, the number of coats required, and the paint's advertised coverage rate (typically 10 m² per liter for smooth walls). This is essential for homeowners, painters, and renovation planners who want to buy enough paint to finish the job in one trip without significant leftovers — or the far worse alternative of running out mid-project when the paint store is closed.
Formula
Paint (L) = [(Perimeter × Height) − Openings] × Coats ÷ Coverage (m²/L).If you have ever stood in front of an ICI or Master paint counter trying to guess how many liters you need for a bedroom, this is the calculation that should have happened before you walked in. Run short by one liter and the painter goes home at 4pm because the local hardware shop closed, the wall sits half-finished overnight, and the next morning the dried edge of yesterday's coat shows as a faint band even after the new paint dries. Buy too much and you have got an extra 4-liter tin you will give to the neighbour or throw out in 18 months. The math here is wall perimeter times ceiling height, minus the openings (doors at roughly 1.85 m squared, windows at 1.5 m squared each), times your number of coats (always two for a new colour), divided by the paint's m squared per liter coverage. Pakistani interior emulsion typically covers 10 m squared per liter on smooth walls, half that on textured plaster or fresh skim coat. Honest take: most homeowners learn the expensive way that 'one-coat coverage' is paint-tin marketing, not reality. Always plan for two coats minimum. Always buy 10 percent extra. Always note the colour code, sheen, and batch number on the lid with a marker before you store the leftover tin for touch-ups.
A paint calculator estimates how much paint you need to cover the walls of a room, taking into account the room's dimensions, the number of doors and windows to subtract, the number of coats required, and the paint's advertised coverage rate (typically 10 m² per liter for smooth walls). This is essential for homeowners, painters, and renovation planners who want to buy enough paint to finish the job in one trip without significant leftovers — or the far worse alternative of running out mid-project when the paint store is closed.
The total wall area equals the room's perimeter multiplied by its ceiling height. Subtract the area of each door (typically 1.85 m² for a standard interior door) and each window (approximately 1.5 m² for a mid-sized window). Multiply by the number of coats you plan to apply — usually two for a new paint color and one for a touch-up — then divide by the paint's advertised coverage rate. Textured or porous walls reduce effective coverage by 20–30%, so adjust the coverage figure downward for those surfaces.
Approximate liters of paint for common wall areas. Assumes standard coverage of 10 m²/L for interior emulsion.
| Wall Area | 1 Coat (L) | 2 Coats (L) | 3 Coats (L) | Typical Usage |
|---|---|---|---|---|
| 10 m² (108 sq ft) | 1.0 | 2.0 | 3.0 | Small bathroom |
| 20 m² (215 sq ft) | 2.0 | 4.0 | 6.0 | Small bedroom |
| 30 m² (323 sq ft) | 3.0 | 6.0 | 9.0 | Master bedroom |
| 50 m² (538 sq ft) | 5.0 | 10.0 | 15.0 | Living / drawing room |
| 100 m² (1,076 sq ft) | 10.0 | 20.0 | 30.0 | 5 Marla house interior |
| 200 m² (2,153 sq ft) | 20.0 | 40.0 | 60.0 | 10 Marla house interior |
| 400 m² (4,306 sq ft) | 40.0 | 80.0 | 120.0 | 1 Kanal house interior |
Interior emulsion covers ~10 m² per liter per coat; exterior weatherproof paint covers only 5–7 m²/L.
Dark colors may need 3 coats to hide completely; light colors usually need 2.
A typical 5 Marla Pakistani home needs ~20 L of interior paint (2 coats) for 100 m² of wall.
Always buy 10% extra paint — touch-ups over 5+ years add up, and paint dye lots change.
A 4 × 5 m room with 3 m ceilings has 54 m² of wall area; at 2 coats and 10 m²/L coverage, you need 10.8 L of paint — roughly three 4-L cans.
Standard interior door openings (1.85 m²) and standard windows (1.5 m²) reduce the paintable area — a typical bedroom loses 3–5 m² to these.
Primer counts as one coat and usually adds 5–8 m²/L coverage depending on the surface, so new drywall often needs primer plus 2 top coats.
Textured walls (popcorn ceilings, stucco, rough plaster) absorb 20–30% more paint than smooth drywall — budget accordingly.
Dark paint over light (or vice versa) often needs 3 coats for complete opacity — calculate assuming 3 coats for strong color changes.
Exterior paint usually has lower coverage (5–7 m²/L) than interior due to weather-protective thickness — use the exterior number from the can.
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