How much paint do you actually need?
Enter your room's dimensions and get a precise answer in gallons, liters, and cans — no sign-up, no guessing, no leftover cans of "eh, close enough."
Quick reference: common room sizes
Rough estimates at 8 ft ceilings, 2 coats, one door and one window deducted. Use the calculator above for your exact numbers.
| Room size | Wall area | Paint needed | Cans (1 gal) |
|---|
Common questions
How much paint do I need for a 12x12 room?
A 12×12 ft room with 8 ft ceilings has about 320 sq ft of wall area before subtracting doors and windows. At two coats and 350 sq ft of coverage per gallon, that's roughly 1.7–2 gallons, or about 3 gallons if you're also painting the ceiling. Use the calculator above with your exact numbers for a precise figure.
How many coats of paint do I need?
Most walls need two coats for even, opaque coverage. One coat can work when you're repainting over a very similar color with a high-quality paint. Three coats are common when covering a dark wall with a much lighter color, or when using a budget paint with weaker hiding power.
How much does a gallon of paint cover?
A gallon typically covers 300–400 sq ft per coat on smooth, primed walls — 350 sq ft is a reasonable middle estimate, and what this calculator uses by default. Textured or unprimed drywall absorbs more paint and may only get 250–300 sq ft per gallon, so bump up the "advanced" coverage field if that's your situation.
Do I need to subtract doors and windows from paint calculations?
Yes, for accuracy — a standard door takes up about 21 sq ft (2 sq m) and a standard window about 15 sq ft (1.4 sq m) of wall that won't get painted. If you'd rather just round up and buy slightly more paint than you need, it's safe to leave both fields at zero.
Should I paint the ceiling with the same paint?
No — ceilings are almost always painted with a flat, ceiling-specific paint that hides imperfections and doesn't reflect light. If you're including the ceiling in this calculator, treat it as a separate can purchase from your wall color.