🎨 Paint Calculator
Calculate exactly how much paint you need for a room. Enter room dimensions, subtract doors and windows, choose number of coats, and get gallons or litres needed along with cost estimate.
Door = 20 sq ft, Window = 15 sq ft excluded per opening. Walls only (ceiling not included).
Frequently Asked Questions
Most interior latex paints cover 350–400 square feet per gallon on smooth, primed surfaces. On rough or porous surfaces (bare drywall, textured walls, older surfaces), coverage can drop to 250–300 sq ft/gallon. Always check your specific paint label for its listed coverage rate.
Two coats are standard for most interior painting projects, especially when changing colors or painting over a dark shade. One coat may suffice if you are painting the same color. Three coats are sometimes needed for highly saturated colors (reds, yellows) or when painting over a very dark color with a light one.
This calculator covers walls only. For ceilings, calculate the floor area (length × width) and add it to your paint needs. Ceiling paint is usually a separate product — white flat finish — and is sold separately.
Priming is recommended for: bare drywall, major color changes (dark to light), stained or repaired surfaces, and new plaster. Primer is typically cheaper than paint and improves adhesion and coverage, often allowing you to use one less coat of finish paint.
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