The Locolory toolkit / Architectural Finishing
Estimate paint gallons, primer, and trim coating for rooms, ceilings, and walls based on coat count and surface condition.
How much square footage does one gallon of paint cover? A typical gallon of interior paint covers about 350 to 400 square feet for one coat on a suitable smooth surface, while porous or textured conditions can reduce practical coverage.
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Paintable area
333 ft²
Exact wall paint
1.78 gal
Full gallon cans
2
Primer gallons
0
Baseboard / trim
48 lin ft
Paint cost
$90.00
Two coats commonly improve pigment distribution, sheen consistency, film thickness, washability, and coverage over repairs or a contrasting color.
Coverage printed on the product label is the controlling estimate. Surface preparation, applicator, color, porosity, texture, and overspray can change yield.
Sherwin-Williams states that a typical gallon covers about 350–400 square feet, while primer is commonly estimated around 200–300 square feet per gallon.
This tool uses 375 ft² for smooth painted surfaces, 300 ft² for textured or porous surfaces, and a conservative 250 ft² paint-and-primer planning rate for fresh drywall.
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A typical gallon covers about 350–400 square feet for one coat on a suitable smooth surface. Product, color, texture, porosity, application method, and film thickness change actual coverage.
Paint-and-primer products do not guarantee one-coat coverage. Two finish coats commonly improve color uniformity, film build, and durability, especially with color changes or porous repairs. Follow the product label.
Calculate gross wall area, then subtract measured opening areas. This estimator offers planning defaults of 21 square feet per door and 15 square feet per window; measuring actual openings is more accurate.
A 12×12 room with an 8-foot ceiling has 384 square feet of gross wall area before openings. At two coats and 375 square feet per gallon, it needs about two gallons for walls after typical deductions, but product coverage and conditions vary.