Paint Calculator
Calculate how much paint you need for a room, accounting for doors, windows, and number of coats.
Why coverage estimates vary
This calculator assumes one gallon covers about 350 square feet per coat, a standard industry estimate — but actual coverage varies by paint brand, wall texture, and paint color. Rough or textured walls absorb more paint than smooth drywall, and darker colors sometimes require an extra coat for even coverage.
Primer is a separate consideration — if you're painting over a drastically different color, unpainted drywall, or a stain, a dedicated primer coat is often needed before your topcoats, which isn't included in this calculation.
Rounding up on paint purchases
Since paint doesn't come in arbitrary fractional amounts, it's practical to round up to the next full gallon or quart rather than buying the exact calculated amount — leftover paint is also useful for future touch-ups, since wall paint can be hard to color-match perfectly later.
For rooms with multiple wall colors or an accent wall, calculate each section separately for the most accurate estimate rather than averaging across the whole room.
Frequently asked questions
Does this include ceiling paint?
No — this calculator estimates wall paint only. Ceilings are typically calculated separately since they often use a different paint type (flat/ceiling-specific paint) and are measured by floor area rather than wall area.
Do I need to paint 2 coats?
Two coats is standard for most projects, especially when changing colors significantly, and generally produces more even, durable coverage than a single coat — though covering a similar existing color with a fresh coat may only require one.