Choose interior paint by surface, sheen and washability: what matt, eggshell and satin change, how to compare technical sheets, and how to test before buying.
Start with the surface
New plaster, previously painted walls, bare wood and masonry need different preparation. Check the product’s instructions against the actual surface before choosing a colour. Bare or repaired surfaces often need sealing first; the primer guide covers when that is necessary.
What sheen changes: matt, eggshell and satin
Lower-sheen finishes reflect less light and make small dents and patches less visible. Higher-sheen finishes are usually easier to wipe clean, but light at a low angle shows any uneven preparation more clearly. Sheen names are not standardised between brands, so one maker’s “eggshell” can be shinier than another’s. Compare the sheen level and cleaning guidance on each product’s technical data sheet rather than the name alone.
Compare washability, not only the label
In Europe, many technical data sheets state a wet-scrub resistance class under EN 13300, where class 1 is the most resistant. A durable matt can therefore suit a hallway better than a less durable eggshell. Ceilings are commonly painted in flat or matt finishes because low sheen hides roller marks and reduces glare.
Test colour and sheen in the room
Paint a sample on a representative wall and look at it in daylight and under the room’s own lighting. Colour and sheen both change with the direction of light. Once the product is chosen, enter its stated coverage and the number of coats into the paint calculator.
Practical checklist
Keep primer and finish from compatible product systems.
Prepare the surface to the level the chosen sheen will reveal.
Record the product name, colour code and sheen for future touch-ups.
Babushka Picks
A short list for the next step
Start with the essential item, add the useful option when it improves the job, and treat the final choice as optional.
Use the values and units in the worked example below; change the assumptions for your own project.
Pre-filled values: Walls
Input
Value
Walls
Length 5 m, Height 2.5 m, Number of walls 2 · Length 4 m, Height 2.5 m, Number of walls 2
Total measured openings
4.7 m²
Coats
2
Coverage per coat
10 m²/L
Extra allowance
10 %
Pack size
2.5 L
Calculated result
Result
Value
Paintable area
40.3 m²
Paint before allowance
8.06 L
Required quantity
8.866 L
Packs to buy
4
Purchase quantity
10 L
Left over
1.134 L
Questions and answers
How does How to Choose Interior Paint work?
Enter different wall lengths, then choose the paint and tin size. Litres = net wall area × coats ÷ coverage, then add the chosen allowance. Tin counts round up; primer and finish coats need separate plans.
What does the worked example show?
Inputs: Walls: Length 5 m, Height 2.5 m, Number of walls 2 · Length 4 m, Height 2.5 m, Number of walls 2; Total measured openings: 4.7 m²; Coats: 2; Coverage per coat: 10 m²/L; Extra allowance: 10 %; Pack size: 2.5 L. Result: Paintable area: 40.3 m²; Paint before allowance: 8.06 L; Required quantity: 8.866 L; Packs to buy: 4; Purchase quantity: 10 L; Left over: 1.134 L.
What should I check before using the result?
Litres = net wall area × coats ÷ coverage, then add the chosen allowance. Tin counts round up; primer and finish coats need separate plans.
Example from an existing calculator
Wall Paint Calculator | Babushka Market. This worked example demonstrates the calculation in the linked tool. Its displayed assumptions apply to that example; use the guidance above to decide which measurements, product specifications or quantities belong to your own task.
Worked example
With Length: 5 m; Height: 2.5 m; Number of walls: 2; Length: 4 m; Height: 2.5 m; Number of walls: 2; Total measured openings: 4.7 m²; Coats: 2; Coverage per coat: 10 m²/L; Extra allowance: 10 %; Pack size: 2.5 L, the calculator returns Paintable area: 40.3 m².
Inputs
Inputs
Changed input
Length
5 m
Height
2.5 m
Number of walls
2
Length
4 m
Height
2.5 m
Number of walls
2
Total measured openings
4.7 m²
Coats
2
Coverage per coat
10 m²/L
Extra allowance
10 %
Pack size
2.5 L
Calculated result
Calculated result
Changed input
Paintable area
40.3 m²
Paint before allowance
8.06 L
Required quantity
8.866 L
Packs to buy
4
Purchase quantity
10 L
Left over
1.134 L
Method and assumptions
Litres = net wall area × coats ÷ coverage, then add the chosen allowance. Tin counts round up; primer and finish coats need separate plans.
Common-value reference
The reference cases change only Total measured openings. The remaining inputs stay at the displayed values. These are worked scenarios, not universal rates, dimensions, product specifications or current shop prices.
Common-value reference
Total measured openings
Paintable area
Total measured openings: 4.7 m²
Paintable area: 40.3 m²
Total measured openings: 2.35 m²
Paintable area: 42.65 m²
Total measured openings: 7.05 m²
Paintable area: 37.95 m²
Total measured openings: 9.4 m²
Paintable area: 35.6 m²
Total measured openings: 14.1 m²
Paintable area: 30.9 m²
Questions and answers
How is this example calculated?
Litres = net wall area × coats ÷ coverage, then add the chosen allowance. Tin counts round up; primer and finish coats need separate plans. In the displayed example, Length: 5 m; Height: 2.5 m; Number of walls: 2; Length: 4 m; Height: 2.5 m; Number of walls: 2; Total measured openings: 4.7 m²; Coats: 2; Coverage per coat: 10 m²/L; Extra allowance: 10 %; Pack size: 2.5 L. The calculated outputs are Paintable area: 40.3 m²; Paint before allowance: 8.06 L; Required quantity: 8.866 L; Packs to buy: 4. Keep the labels and units with these numbers: they describe this particular combination of inputs, not a result that can be reused after the measurements or assumptions change.
What changes when I edit Total measured openings?
The table isolates that input while keeping the other displayed settings fixed. For Total measured openings: 2.35 m², the result is Paintable area: 42.65 m²; for Total measured openings: 14.1 m², it is Paintable area: 30.9 m². Those values come from the same calculator used on this page. They show the effect of changing the input, rather than prescribing which input is right for your own task.
How should I use the different result figures?
Read each named quantity separately: Paintable area: 40.3 m²; Paint before allowance: 8.06 L; Required quantity: 8.866 L; Packs to buy: 4. A value with a different label or unit answers a different part of the calculation. Check the measurements and assumptions before using any figure. The reference cases explain the arithmetic under their stated conditions; they do not verify a product label, a recipe or the conditions of a particular project.
