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Calculate paint gallons for walls and ceilings. Enter room dimensions, coats, and coverage rate to get primer and paint gallons with waste allowance.
Estimate spray paint cans for projects from surface area and coverage. Calculate primer, color coats, and clear coat cans for metal, furniture, and crafts.
Calculate wallpaper rolls from room dimensions and roll size. Account for pattern repeat, waste, and drops for single and double roll coverage estimates.
Porous and stained surfaces reduce spread rate. Read manufacturer label for specific product.
Drywall: 300–400 sq ft/gal; Masonry: 200–300 sq ft/gal; Stain-block: 250 sq ft/galOne coat primer standard. Severe stains (smoke, tannin bleed) may need two coats stain-blocking primer.
Gallons = ceil(Area ÷ Coverage Rate)Primer is always calculated on bare or prepped surface area before finish coat math.
Total Project = Primer Gallons + Finish Gallons × CoatsUpdated: July 2026
PVA drywall primer at 350 sq ft/gal = 3.4 gal → 4 gallons. Seal entire surface before topcoat.
Oil-based stain-blocking primer at 250 sq ft/gal — 1 quart sufficient. Shellac primer for smoke damage.
Masonry primer at 225 sq ft/gal = 1.8 gal. Allow 24 hr cure before exterior latex topcoat.
Calculate primer quantity separately from finish paint for proper surface preparation. Enter wall area and substrate type (new drywall, stained wood, masonry) to apply correct coverage rate and coat count.