Paint Quantity & Coverage

The deterministic quantity & coverage cluster — the highest-demand paint queries: a how-much-paint calculator (the signature metric, gallons = ceil(paintable area × coats ÷ coverage)), a wall/room square-footage calculator (perimeter × height), a ceiling paint calculator (L × W), a primer calculator, a paint-coverage calculator (links the signature dataset), a trim/baseboard linear-feet calculator, and an exterior siding paint calculator. Measure your actual surfaces and confirm coverage on the can; round up to whole gallons.

Measure your actual surfaces and confirm coverage against the paint you buy. Rough or porous surfaces, a big color change and extra coats all use more paint — allow extra for texture, porosity and waste, and round up to whole gallons/quarts. Coverage varies by product and surface; read the can’s stated spread rate.
Typical published planning values — NOT a certified spec or professional advice. Coverage and coats vary by product, surface, texture and color; confirm on the paint can’s stated spread rate and the manufacturer’s data. Surface prep, moisture/adhesion and pre-1978 lead paint are a pro’s call — follow the EPA RRP rule and hire a certified firm; lead-paint abatement, structural repairs and code certification are not engineered here.
How Much Paint CalculatorWork out how many gallons of paint you need: paintable wall area (perimeter × height − doors and windows) × coats ÷ coverage, rounded up to whole gallons. Free, no signup.Wall & Room Square FootageFind a room's wall square footage: perimeter (2 × (length + width)) × wall height. The base number behind every paint quantity and cost estimate. Free, no signup.Room Paint CalculatorEstimate paint for a whole room: wall gallons (perimeter × height − openings, at your coats) plus ceiling gallons (length × width, one coat). Free, no signup.Ceiling Paint CalculatorHow much ceiling paint you need: area = length × width, gallons = ceil(area × coats ÷ coverage). Handles smooth and textured ceilings. Free, no signup.Primer CalculatorHow much primer you need: gallons = ceil(area ÷ primer coverage). Primer spreads thinner than paint (typ 200–300 sq ft/gal). Free, no signup.Paint Coverage CalculatorHow far your paint goes: area covered = gallons × coverage per gallon (one coat), and gallons needed for your coats. Uses the coverage-by-surface dataset. Free.Trim & Baseboard Linear FeetMeasure trim and baseboard the right way — by the linear foot: trim_lf = (run − door widths) × (1 + waste). Add ~10% for miters and offcuts. Free, no signup.Exterior Siding Paint CalculatorHow much paint for exterior siding: net area = wall perimeter × total wall height − openings; gallons = ceil(net × coats ÷ coverage). Plans painting existing siding. Free.

Every Paint Quantity & Coverage tool is calculated server-side — visible immediately — with its formula, a worked example and a reference table, and works on the surfaces you measure and the prices you enter from your own quotes. Background reading is in the guides.