Paint Calculator
Calculate how much paint you need for your room based on dimensions and number of coats.
How much area does a gallon of paint cover?
Coverage depends on surface and quality: Smooth walls/primer: 350-400 sq ft per gallon. Textured/porous surfaces: 250-300 sq ft per gallon. First coat: Lower coverage. Second coat: Higher coverage (350-400 sq ft). High-quality paint covers better than cheap paint. Example: 20'x15' room with 8' walls = 560 sq ft, needs 1.6 gallons first coat, 1.4 gallons second coat = 3 gallons total. Always round up when buying.
How many coats of paint do I need?
Standard: 2 coats for even color and durability. Situations needing more: Dark to light color change (2-3 coats or tinted primer), New drywall (prime + 2 coats), Stain blocking (prime + 2 coats), High-traffic areas (2-3 coats for durability). One coat only works: Light to light color, high-quality paint, previously painted same color. Primer counts as one coat. Two quality coats always better than three cheap coats.
Should I use primer before painting?
Always use primer for: New drywall (seals porous surface), drastic color changes (tint primer close to final color), stain coverage (oil-based primer blocks stains), glossy surfaces (bonds better than paint alone), repairs (evens texture). Skip primer only: Same or similar color, previously painted surface in good condition, paint-and-primer-in-one (though separate primer still better). Primer is cheaper than paint - saves money on fewer topcoats needed.
How do I calculate paint for trim and ceilings?
Trim: Measure linear feet of baseboard, crown molding, door/window casings. Multiply by average width (typically 4-6 inches = 0.4 sq ft per linear foot). Example: 100 linear feet x 0.4 = 40 sq ft, needs 0.25 gallons (but buy 1 quart minimum). Ceiling: Length x Width. Example: 20'x15' = 300 sq ft = 1 gallon. Use semi-gloss for trim, flat/eggshell for ceilings. Separate colors for walls, trim, ceiling require separate calculations.