Paint Calculator — Gallons, Primer & Cost
Enter room dimensions and coats to size paint, primer and labor for interior or exterior work.
Your numbers
Results
- Wall area
- 362 sq ft
- Wall paint2 coats @ 375 sq ft/gal
- 2.0 gal
- Ceiling paint1 coat flat
- 0.5 gal
- Primernew or patched drywall
- 1.5 gal
- Trim & baseboard~0.5 gal enamel
- 52 lin ft
- Estimated labor
- $721 – $1,018
Quantities are estimates for planning. Verify spans, spacing and local amendments before ordering.
How the math works
- Wall area = perimeter × height, minus 18 sq ft per opening. One gallon covers about 350–400 sq ft per coat on primed drywall.
- Primer is figured at one coat over 300 sq ft per gallon — porous or patched surfaces absorb more.
- Trim paint is figured at roughly 250 linear feet per gallon of enamel.
Code & best practice
- Bare drywall, heavy color changes and stain-blocking all require a dedicated primer coat.
- Homes built before 1978 fall under the EPA RRP rule — disturbing paint requires a certified renovator.
- Exterior work needs surface temperatures above 50°F and no rain for 24 hours after the final coat.
Frequently asked questions
How much paint do I need for a 12x14 room?
About 2 gallons for two coats on the walls, plus roughly half a gallon for the ceiling.
How many square feet does a gallon of paint cover?
350–400 sq ft per coat on a smooth primed surface; textured walls drop to about 300.
Do I need primer?
Yes on bare drywall, raw wood, patched areas, stains, or when going from a dark color to a light one.