Paint Calculator

A 12x12 room with 8-foot ceilings has about 384 square feet of wall area. Subtract a door (about 21 sq ft) and a window (about 15 sq ft), and you have roughly 348 square feet of paintable surface. With 2 coats and standard coverage of 350 sq ft per gallon, you'll need about 2 gallons of paint.

A gallon of interior latex paint typically covers 350-400 square feet per coat on smooth surfaces. Textured walls, unpainted drywall, or porous surfaces can reduce coverage to 200-300 sq ft per gallon. Premium paints sometimes offer higher coverage, around 400+ sq ft per gallon.

Gallons are more cost-effective per unit volume. Quarts typically cost about 30% of the gallon price but only contain 25% of the paint. Buy gallons for large areas, and quarts only for small touch-ups or accent walls under 100 square feet. This calculator shows the best combination.

For vaulted or cathedral ceilings, use this calculator's manual mode. Measure each wall separately, calculate the area of triangular or trapezoid walls (base * average height), then enter the total wall area. Remember to subtract doors and windows as usual.

Yes. Primer coverage differs from paint, typically 200-300 square feet per gallon. If painting over dark colors, new drywall, or stained surfaces, add a primer coat before the paint coats. Some paint-and-primer combo products may skip this step, but separate primer works better on problem surfaces.

Buy 10-15% extra paint to account for touch-ups, mistakes, and future repairs. This calculator rounds up to the nearest gallon, which usually provides that buffer. Store leftover paint sealed for future touch-ups, since exact color matching can be difficult later.

Textured walls absorb more paint. For light texture, reduce coverage to about 300 sq ft per gallon. For heavy texture like stucco or popcorn, use 200-250 sq ft per gallon. Adjust the coverage field in this calculator to match your wall texture for a more accurate estimate.