Question 1

How much paint does one liter actually cover?

Accepted Answer

Coverage depends heavily on the surface texture and the paint itself, but a common planning figure is roughly 10 square meters per liter per coat on a smooth interior wall, a bit less on textured exteriors, and less again for brushed wood or metal trim. This tool uses separate coverage rates for each surface type as a starting estimate — always check the coverage figure printed on your specific paint can, since formulations vary.

Question 2

Why does the estimate change so much with the number of coats?

Accepted Answer

Paint quantity scales directly with coats — two coats need roughly twice the paint of one. Two coats is standard for most new work and color changes; a single coat is sometimes enough for a same-color touch-up or when using a high-opacity paint over a similar existing color.

Question 3

Should I subtract doors and windows even for a small deduction?

Accepted Answer

Yes — the deduction can meaningfully change the material count, especially on smaller walls where a door or window makes up a large share of the surface. Measure width × height for each opening and add them together for the total deduction.

Question 4

Why round up to whole containers?

Accepted Answer

Paint is sold in fixed container sizes, so any leftover fraction still requires buying a full extra container. Rounding up avoids running out mid-job — a common and more costly problem than a small amount of leftover paint.

Gross wall area	36 sq m
Paintable area (after deductions)	32 sq m
Coats	2
Total liters needed	6.4 L

Paint Quantity & Cost Estimator

How the estimate is calculated

Common questions