Paint Coverage & Volume Calculator - buildercalc

One gallon of interior latex paint covers 350 to 400 square feet on smooth, primed surfaces (approx 35-37 sq meters per gallon).

Calculate total paintable wall area, divide by coverage per gallon (350-400 sq ft), and multiply gallons needed by 2.

Yes, subtract standard door openings (20 sq ft) and windows (15 sq ft) for accurate paint requirements, unless openings are small.

Primer is necessary on new unpainted drywall, bare wood, repaired plaster, dark-to-light color transitions, and glossy oil-based surfaces.

Rough or textured surfaces (knockdown, popcorn, brick) absorb more paint, reducing coverage by 15% to 25% (250-300 sq ft per gallon).

Standard low-VOC paints contain less than 50 grams per liter (g/L) of Volatile Organic Compounds; zero-VOC paints contain less than 5 g/L.

Wait 2 to 4 hours between coats for water-based acrylic latex paints. Oil-based alkyd paints require 24 hours cure time before recoating.

Semi-gloss or satin/eggshell premium moisture-resistant finishes are best for high-humidity areas due to wipeability and moisture resistance.

Ceiling area equals room length x width. Standard flat white ceiling paint covers 350-400 sq ft per gallon in a single coat.

Store latex paint in a cool, dry place sealed tightly upside down to seal the rim. Properly sealed paint lasts 2 to 5 years.

DFT is the thickness of cured paint measured in mils (1 mil = 0.001 inch). Standard wet film of 4 mils dries to approximately 1.5 mils DFT.

Use 515 or 517 tips (0.015-0.017" orifice, 10" fan) for wall latex paint; use 311 or 313 fine-finish tips for trim and doors.

Back-rolling uses a roller immediately after spraying to push paint into porous drywall texture and ensure uniform mechanical adhesion.

Apply latex paint between 50°F and 90°F with relative humidity under 85%. High humidity slows water evaporation, causing sagging and sheen variation.

Spreading Rate (sq ft/gal) = (1604 x % Solids by Volume) / Target Wet Film Thickness (mils).

Scuff sand oil paint, clean thoroughly, and apply a 100% acrylic bonding primer before applying latex topcoats to prevent peeling.

ASTM D2486 scrub resistance test rates high-performance paints that withstand over 1,000 continuous abrasive scrub cycles.

Estimate 1 gallon of semi-gloss enamel for every 500 linear feet of 4-inch baseboard and door trim (2 coats).