Paint Coverage Calculator
Estimate gallons of paint needed for any surface area.
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View on Amazon →Estimate gallons of paint needed for any surface area.
Typically 350–400 sq ft per coat. High-porosity surfaces need more.
Yes — add 10% for trim, edges, and touch-ups.
Perimeter × ceiling height, minus doors and windows.
Results are estimates for planning purposes. Verify with product labels and local requirements before purchasing materials.
Paint coverage refers to the area—measured in square feet—that one gallon of paint can adequately cover. Understanding coverage is essential for any painting project because buying the wrong amount of paint wastes money and creates hassles. Too little paint means extra trips to the store; too much leaves you with excess that may dry out or never get used.
Coverage depends on several factors: the surface texture, the quality of the paint, how many coats you're applying, and whether you're painting over a dark color with a light one. A smooth, previously painted wall might accept 400 square feet per gallon, while new drywall or rough textures might only take 250–300 square feet. The paint formula, pigment quality, and thickness all affect how far a gallon actually goes.
This calculator takes the guesswork out of your estimate. Enter your total surface area, choose your number of coats, select your paint's coverage rate, and add a waste factor. The calculator instantly tells you how many gallons to buy, accounting for trim, edges, and the 10% extra you should always have on hand for touch-ups and future maintenance.
Start by calculating the total surface area to be painted in square feet. For walls, multiply the perimeter of the room by the ceiling height, then subtract the area of doors and windows.
The full formula is: Gallons needed = (Area × Coats × Waste factor) ÷ Coverage rate
A standard gallon covers 350–400 sq ft on a typical wall. New drywall or rough surfaces need more paint — estimate 250–300 sq ft per gallon.
| Surface type | Coverage per gallon | Notes |
|---|---|---|
| Smooth, previously painted wall | 375–400 sq ft | Standard coverage for repaints |
| New drywall (after primer) | 350–375 sq ft | Prime first for best results |
| Rough or textured surface | 250–300 sq ft | More surface area absorbs more paint |
| Bare wood (after primer) | 300–350 sq ft | Very porous without primer |
| Concrete or masonry | 200–300 sq ft | May need two primer coats |
Example: 14×16 ft living room with 9 ft ceilings, 2 doors, 3 windows
Step 1 — Wall perimeter: (14 + 16) × 2 = 60 linear feet
Step 2 — Wall area: 60 × 9 = 540 sq ft
Step 3 — Subtract openings: 2 doors × 20 sq ft = 40, 3 windows × 15 sq ft = 45. Subtract 85 sq ft.
Step 4 — Net wall area: 540 − 85 = 455 sq ft
Step 5 — Two coats at 375 sq ft/gal: (455 × 2) ÷ 375 = 2.43 gallons
Step 6 — Add 10% waste: 2.43 × 1.10 = 2.67 gallons
Buy 3 gallons of wall paint plus 1 quart for touch-ups.
Ceiling (14×16 = 224 sq ft, 1 coat): 224 ÷ 400 = 0.56 gallons — buy 1 quart.
| Finish type | Sheen level | Best rooms | Washability |
|---|---|---|---|
| Flat / matte | None | Ceilings, low-traffic walls | Low |
| Eggshell | Very slight | Bedrooms, living rooms | Moderate |
| Satin | Soft glow | Kitchens, family rooms | Good |
| Semi-gloss | Noticeable | Bathrooms, trim, cabinets | Very good |
| Gloss | High shine | Doors, furniture, trim | Excellent |
A 12×12 ft room with 8 ft ceilings has roughly 320 sq ft of wall space after subtracting one door (20 sq ft) and two windows (30 sq ft total). One gallon covers that in one coat. Buy 2 gallons for two coats, plus extra for the ceiling.
A gallon of paint typically covers 350–400 square feet per coat on smooth, previously painted surfaces. Rough textures, bare drywall, and dark-over-light color changes reduce coverage to 250–300 sq ft per gallon.
Two coats are standard for most painting projects. New drywall may need a primer coat plus two finish coats. Dramatic color changes — dark to light or light to dark — often require three coats for complete, even coverage.
Yes. Buy 10% more than your calculation. Keep any leftover paint sealed tightly and labeled with the room and color for future touch-ups. Paint is typically sold in quarts (1/4 gallon) for small quantities.
Flat/matte for ceilings and low-traffic walls. Eggshell for bedrooms and living rooms — some sheen, easy to clean. Satin for kitchens and family rooms. Semi-gloss for bathrooms and trim. Gloss for doors and high-wear surfaces.
Multiply the room length by the width. That's your ceiling square footage. Divide by your paint's coverage rate (usually 400 sq ft/gal for ceilings) and add 10% waste.
Primer seals porous surfaces, improves paint adhesion, and provides a neutral base for accurate color. Use primer on new drywall, bare wood, or when making dramatic color changes. Primer-and-paint-in-one products save a step but rarely match separate primer quality.
Usually yes. Premium paints have higher pigment concentration, often covering in one coat where budget paint needs two. Factor the cost-per-coat, not just cost-per-gallon, when comparing.
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