Paint Coverage Calculator
Check how far your paint will go. Coverage per gallon by finish type, plus how many gallons your project needs.
Enter room details and how many gallons you have. Click Calculate.
Paint Coverage by Finish (per Gallon, One Coat)
One gallon covers roughly 350–400 sq ft on smooth, primed walls. The finish you choose moves that number a little — here's the typical range.
| Paint Type / Finish | Coverage per Gallon (sq ft) | Best For |
|---|---|---|
| Flat / matte | 375 – 425 | Low-traffic walls, ceilings — hides imperfections best |
| Eggshell | 350 – 400 | Living rooms, bedrooms — washable but low sheen |
| Satin | 325 – 375 | Kitchens, bathrooms, trim — more durable |
| Semi-gloss | 300 – 350 | Trim, doors, cabinets — scrubbable |
| High-gloss | 275 – 325 | Doors, trim, furniture — most durable, shows flaws |
| Primer | 300 – 350 | New drywall, stain blocking, color changes |
| Exterior (any finish) | 250 – 350 | Siding, brick, stucco — rougher surfaces drink more |
These are manufacturer-standard one-coat figures on smooth, primed surfaces. Rough, unpainted, or dark-to-light color changes cut coverage by 10–30%.
What Changes Your Real-World Coverage
Surface texture
Smooth drywall hits the 350–400 sq ft mark. Brick, stucco, and popcorn ceilings are the opposite — expect 15–45% less coverage because the paint fills texture instead of lying flat.
Color change and paint quality
Going dark-to-light (or reds/yellows) can need an extra coat, effectively cutting your per-gallon coverage. Cheap one-coat paints also cover less than premium brands per coat.
Application method
Sprayers waste 15–20% to overspray. Rollers lose a little to the nap, brushes least of all — but rollers even out the coat best. Our calculator applies a waste factor for each method.
Surface condition
Unpainted drywall soaks up primer like a sponge — always prime first, then count finish coats on the primed surface. Painted walls in good shape are the cheapest to cover.
Coats you actually need
Two coats is the norm, three when changing color drastically. Each coat uses a full gallon-per-area pass — doubling coats halves your square-foot coverage per gallon.
How Coverage Is Calculated
Coverage per gallon (sq ft, one coat) ÷ surface area (sq ft) = gallons needed per coat. Multiply by coats, then apply surface and application-method factors. Our calculator uses 350 sq ft/gallon as the default and lets you adjust it.
Coverage figures follow standard manufacturer ratings (350–400 sq ft per gallon per coat on smooth primed walls) as confirmed by HomeGuide, plus the U.S. Bureau of Labor Statistics OEWS for labor context (SOC 47-2141, median wage $23.75/hr, May 2025). [1][2]
Sources & References
- [1]U.S. Bureau of Labor Statistics — OEWS, Painters (SOC 47-2141), median wage $23.75/hr (May 2025)
- [2]HomeGuide — Paint Coverage Data (350–400 sq ft per gallon)
- [3]HomeGuide — Cost to Paint a Room ($300–$1,000; labor $20–$50/hr)
Numbers marked [1], [2], [3] in the tables and answers above reference the sources below.
Real-world coverage varies with surface, paint quality, and application. When in doubt, buy 10% extra — leftover paint is cheaper than a second trip to the store.
Frequently Asked Questions About Paint Coverage
How many square feet does a gallon of paint cover?
About 350–400 sq ft per coat on smooth, primed walls. Rough surfaces and exteriors drop that to 250–350 sq ft. [2]
How much paint do I need for a 12x12 room?
A 12x12 room with 8-ft ceilings has roughly 340–380 sq ft of paintable wall area (minus doors/windows). One coat ≈ 1 gallon; two coats ≈ 2 gallons.
Does one coat of paint cover?
On a primed or previously painted wall in the same color family, one coat can work. On new drywall, bare wood, or a big color change, plan on two — sometimes three.
Is a gallon of cheap paint the same as premium?
No. Premium paints carry more pigment and binder, so they cover better per coat and often need fewer coats — the cheaper gallon can end up costing more in total.
How many gallons for 1,000 sq ft of wall area?
At 350–400 sq ft per gallon per coat, 1,000 sq ft needs about 3 gallons for one coat or 5–6 gallons for two coats.