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Estimate gallons of paint needed for any room with cost and coverage details.
A paint calculator estimates the number of gallons required to cover walls by calculating total surface area minus doors and windows, then dividing by the paint's coverage rate.
| Finish | Sq Ft/Gal | Notes |
|---|---|---|
| Flat / Matte | 350 | Best coverage, hides imperfections |
| Eggshell | 350 | Slight sheen, easy to clean |
| Satin | 350 | Moderate sheen, durable |
| Semi-Gloss | 350 | Shiny, moisture-resistant |
| Gloss | 300 | Highly reflective, hardest finish |
| Primer | 300 | Base coat, needed for new drywall |
| Textured Paint | 200 | Thick, lower coverage |
Formula
Gallons = (Net Wall Area × Coats) ÷ Coverage per GallonNet Area = 2×(L+W)×H − (Doors×20) − (Windows×15) sq ft
Coats = number of paint coats (typically 2)
Coverage = ≈350 sq ft per gallon for standard interior paint
Worked Example
12×10 ft room, 8 ft ceilings, 1 door, 2 windows, 2 coats
Did you know? One gallon of paint covers roughly 350–400 sq ft per coat on smooth drywall, but porous or textured surfaces can reduce that to 200 sq ft per gallon.
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