Paint Calculator
Gallons of paint and primer for rooms and exteriors. Updated for 2026.
Last reviewed July 2026 · Free · Nothing you enter is stored
—
Planning estimate using standard formulas and 2026 national average prices — confirm quantities with your supplier and get local quotes.
Advertisement
How this calculator works
Coverage uses the industry standard of 350 sq ft per gallon per coat for paint (real-world range 300–400 depending on texture and porosity) and 250 sq ft per gallon for primer. Results round up to whole gallons per product, the way you actually buy it. Costs use 2026 averages: about $45/gallon for mid-grade interior paint ($28 economy, $70+ premium).
Frequently asked questions
How much area does a gallon of paint cover?
About 350 square feet per coat on smooth, previously painted walls — less on texture, bare drywall, or masonry (as low as 250–300). Check your specific paint's label; manufacturers print the tested rate.
How many gallons do I need for a 12x12 room?
About 1.5 gallons for two coats on the walls (≈350 sq ft of wall after subtracting a door and window), so buy two gallons. Add a quart or gallon for the ceiling if you're doing it too.
Is expensive paint worth it?
Usually, yes — premium paints ($50–$100/gal) hide better, often covering in fewer coats, and scrub cleaner. If a $70 paint covers in one coat where a $30 paint needs two, the premium can is the same price with half the labor.
Advertisement