Painting Calculators
A gallon of paint covers a predictable area — but only after you subtract windows and doors and decide how many coats you are applying. These calculators estimate paint gallons for rooms or exteriors, plus wallpaper rolls with the pattern-repeat math that trips up most first-timers. Enter your wall dimensions once and stop buying three extra gallons just in case.
Paint CalculatorGallons, wall area, and primer — from room dimensions or total area.PaintingWallpaper CalculatorRolls, strips, and pattern-match waste for any wall — US or European rolls.Painting
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Painting FAQs
Roughly 350–400 square feet per gallon per coat on smooth, primed surfaces — a manufacturer rule of thumb. Rough, textured, or unprimed surfaces absorb more, so the calculator lets you set coats and adjust for surface condition.
Patterns must align across adjacent strips, so every strip sacrifices one repeat length to matching. A large repeat can add a full extra roll to a room — the wallpaper calculator factors the repeat into the roll count.
Estimates are planning guides, not professional advice. Read the disclaimer.