Paint Calculator

Calculate how many gallons of paint you need for walls, ceilings, or trim. Enter your room dimensions and we'll subtract doors and windows automatically.

How Much Paint Do I Need?

One gallon of paint covers approximately 350–400 square feet per coat on smooth interior walls. For textured or porous surfaces, plan on 250–300 sq ft per gallon. Two coats is the standard for a proper finish.

Paint Coverage by Surface

Smooth Drywall (350–400 sq ft/gal)

Standard interior walls. One gallon covers a typical 12×14 bedroom with 8-foot ceilings in one coat.

Textured Walls (250–300 sq ft/gal)

Orange peel, knockdown, and heavy textures absorb more paint. Add 20–30% to your estimate.

Brick or Concrete (150–200 sq ft/gal)

Porous surfaces drink paint. Always use a primer first to reduce absorption.

Ceilings (350–400 sq ft/gal)

Same coverage as walls. Flat ceiling paint is standard and hides imperfections better than satin or semi-gloss.

Frequently Asked Questions

How many gallons for a 12x12 room?

A 12×12 room with 8-foot ceilings has about 384 sq ft of wall area. Subtract doors and windows, and you need roughly 1 gallon per coat. Two coats = 2 gallons.

Should I buy 1-gallon or 5-gallon buckets?

For a single room, buy 1-gallon cans — leftover paint stays fresh longer. For multiple rooms or whole-house painting, 5-gallon buckets save 20–30% per gallon.

Do I need primer?

Always prime if you're painting over bare drywall, dark colors, stains, or glossy surfaces. Primer costs $15–$30/gallon but saves 1–2 topcoats and gives better color accuracy.

How long does paint take to dry?

Most latex paints are dry to the touch in 1 hour and recoatable in 2–4 hours. Oil-based paints take 6–8 hours before recoating. Humidity extends drying time.