Reference tables
Look-up charts built from stable paintable-area geometry and labeled industry planning typicals — paint coverage by surface, number of coats by scenario, standard door & window deductions, cost-per-square-foot and per-room planning bands, and recommended sheen by surface.
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.
Paint coverage / spread rate per gallon by surfaceThe signature reference: labeled paint coverage / spread rate per gallon by paint type & surface, one coat — from smooth drywall (~350–400) to unpainted brick (~100–200).Number of paint coats by scenarioThe signature companion: labeled number of coats by scenario — 1–2 for a like color, 2 for new drywall, 2–3 + primer for a dark→light change.Standard door & window area deductionslabeled standard opening area deductions — interior door ≈ 21 sq ft, window ≈ 15 sq ft, patio door ≈ 40 sq ft.Painting cost-per-square-foot planning bandslabeled all-in $/sq ft painting planning bands (interior, interior + ceilings/trim, exterior) — a sanity guide only, you enter the real price.Painting cost-per-room planning bandslabeled per-room $ painting planning bands (bedroom, bathroom, living room, kitchen walls) — a sanity guide only.Recommended paint sheen by room & surfacelabeled recommended sheen by room/surface — flat for ceilings, eggshell/satin for most walls, satin/semi-gloss for kitchens, baths, trim & doors.