CostBuildrPaint Calculators
Paint is bought by the liter but applied by the square foot, and the gap between the two catches many builders off guard. A single miscalculation can leave you a bucket short on the final wall or stuck with expensive surplus in a custom-tinted color you cannot return. Use this calculator to get a precise paint quantity based on your wall area, number of coats, and the coverage rate of your chosen product.
Common questions
What is the typical coverage rate for interior wall paint?
Most standard interior emulsion paints cover 120–140 sq ft per liter on a smooth, primed surface in a single coat. Textured or unpainted plastered walls absorb more paint and may only yield 80–100 sq ft per liter on the first coat. Always check the coverage figure printed on the paint can, as it varies by brand and finish type (matte finishes tend to cover slightly more area than gloss or satin).
How many coats of paint do I need?
Two coats is the standard for most repainting jobs over an existing similar color. If you are covering a dark color with a lighter one, or painting fresh plaster for the first time, plan for a primer coat plus two finish coats (three coats total). High-quality paints with better pigment density sometimes achieve full coverage in two coats even over contrasting colors — but budgeting for a potential third coat avoids mid-project shortages.
Should I calculate ceiling paint separately from wall paint?
Yes. Ceilings are usually painted with a flat/matte finish (which hides imperfections when viewed from below), while walls may use satin or semi-gloss for durability. The coverage rates differ, and you often want a different color or sheen for the ceiling. Calculate ceiling area (length × width of the room) separately, apply the ceiling paint's coverage rate, and order it as a distinct line item.
Do I need primer, and does it reduce the paint I need?
Primer is recommended on new plaster, bare drywall, repaired patches, and any time you are making a drastic color change. It seals the surface so the finish paint does not get absorbed unevenly, which means your topcoats cover better and you may need fewer finish coats. On previously painted walls in good condition where you are using a similar color, a self-priming paint can sometimes skip the dedicated primer step — but fresh surfaces should always be primed.