Calculator
Paint Calculator
Figure out how many gallons of paint and primer your room or exterior needs.
Verified August 2026
Paint needed
2.3 gallons
2 coats
- Paintable area
- 396 sq ft
- Buy
- 3 gallons
- Primer (1 coat)
- 1.2 gallons
- Paint cost estimate
- $114 – $234
Estimates only. Local pricing, site conditions and code requirements change the real number.
The formula
Paintable area = wall area - door and window area; Gallons = (area x coats) / coverage
One gallon covers roughly 350 square feet on smooth surfaces and closer to 275 on stucco or heavy texture, which is common in Florida.
Worked example
A 12 x 14 room with 9 ft ceilings has about 468 sq ft of wall. Two coats needs roughly 3 gallons.
Frequently asked questions
How much does a gallon of paint cover?
About 350 square feet per coat on smooth walls. Stucco, popcorn ceilings and rough masonry drop that to 250-300 square feet.
Do I need primer?
Prime bare drywall, patched areas, stained surfaces and any dramatic color change. Over an existing similar color in good condition, a quality paint-and-primer usually suffices.
Sources
Sources & verification
Last verified August 2026. Cost figures are modeled estimates based on national baselines adjusted for local labor and material pricing — they are not quotes. Permit rules change; confirm with the building department before starting work.