Paint Calculator (Square Footage)

Most quality interior latex paints rate at 350 to 400 sq ft per gallon for one coat on smooth, sealed drywall. That number drops on porous, textured, or unprimed surfaces.

For most rooms you'll do two coats. Plan for around 175 sq ft of finished wall per gallon. A 12×14 room with 8 ft ceilings (about 416 sq ft of wall) needs around 2.5 gallons for two coats — round up to 3.

New drywall, dramatic color changes (dark to light), stain coverage, and high-gloss surfaces all benefit from primer. One gallon of primer typically covers 300 sq ft.

Skip primer only when you're repainting a similar color over an existing finish in good condition.

The standard answer — a gallon covers 350 sq ft per coat — works for smooth walls and average paint quality. Real-world coverage varies more than people expect.

Premium paints (Sherwin-Williams Emerald, Benjamin Moore Aura) cover 400-450 sq ft per gallon and often need only 2 coats over a similar color. Budget paints (contractor-grade) cover 250-300 sq ft per gallon and need 3 coats for full hide. The premium paint is usually cheaper per coverage-foot despite the higher sticker price.

Coverage drops for: textured surfaces (15-25% less), color changes (3 coats minimum), bare drywall (primer required first), and ceiling paint (typically 250-300 sq ft per gallon because of the flat formula).

Worked numbers: a 12 × 14 ft bedroom (374 sq ft net wall area) needs 374 × 2 coats = 748 sq ft = 2.14 gallons of standard paint. Round up to 3 gallons or accept the risk that you might need to buy 1 more quart later — at which point the dye lot won't match perfectly.

Primer is required: on bare drywall (new construction), bare wood, dramatic color changes (dark to light, white to red), water-stained or repaired walls, and any surface with mildew or grease.

Primer is optional: when repainting the same color family on existing finished walls, when using paint-and-primer-in-one over a similar color, and on glossy surfaces if the topcoat is also glossy.

Primer coverage rate is 300 sq ft per gallon, lower than topcoat. For 374 sq ft of wall: 1.25 gallons of primer = 2 gallons (round up). Primer is usually less expensive per gallon than topcoat, and one primer coat is sufficient even when topcoat needs two.

Tinted primer for dark colors: have your primer tinted toward the topcoat color. A pink primer under red dramatically reduces the number of red coats needed. Most paint stores tint primer at no extra cost.

Exterior paint covers less square footage per gallon than interior paint because exterior surfaces are typically rougher and more porous.

Exterior paint coverage: 250-350 sq ft per gallon on smooth siding, 200-275 on rough/textured siding, 150-200 on brick or stucco, 200-250 on bare wood.

A 2,000 sq ft house typically has 1,500-1,800 sq ft of exterior wall after subtracting windows and doors. Two coats: 3,000-3,600 sq ft ÷ 275 = 11-13 gallons of paint. Buy a 5-gallon bucket plus extra individual gallons.

Trim paint is bought separately, typically in quart cans. One quart covers about 90 sq ft of trim. A 2,000 sq ft house has 100-150 linear feet of exterior trim — about 75-100 sq ft of trim area — so 1-2 quarts of trim paint suffices.