How Many Square Feet Does a Gallon of Paint Cover? Manufacturer Spread Rates Compared

By Sam Whitaker · Updated 2026-10-04

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A gallon of interior wall paint covers about 350 to 450 square feet per coat, according to the technical data sheets manufacturers publish for each product. Thick exterior and high-build paints cover less, about 250 to 350 square feet, because they are meant to go on heavier. Coverage is not a property of “paint” in general. It follows from how thick the product is designed to be applied, and then from the surface it lands on.

This page compares the published spread rates of nine products, shows the arithmetic that links coverage to film thickness, and turns a coverage range into a shopping list. It also covers the decisions that coverage cannot make: primer, coat count over dark colors, and separate ceiling and wall orders.

Published spread rates for nine paints

Each figure is copied from the manufacturer’s product or technical data sheet. “Wet mils” is the thickness of the wet coat the maker designed the rate around; one mil is a thousandth of an inch.

Product	Use	Spread rate per gallon	Wet film	Dry film
Sherwin-Williams SuperPaint Interior Latex Flat	Interior walls	350–400 sq ft	4 mils	1.4 mils
Sherwin-Williams Emerald Interior Latex Satin	Interior walls	350–400 sq ft	4 mils	1.6 mils
Benjamin Moore Regal Select Interior Flat (N547)	Interior walls	400–450 sq ft	3.6–4.0 mils	1.6–1.9 mils
Benjamin Moore Regal Select Interior Eggshell (N549)	Interior walls	400–450 sq ft	3.6–4.0 mils	1.6–1.8 mils
Benjamin Moore Ben Interior Eggshell (N626)	Interior walls	400–450 sq ft	3.6–4.0 mils	1.4–1.6 mils
Benjamin Moore Advance Waterborne Alkyd High Gloss (N794)	Trim, doors, cabinets	400–500 sq ft	3.2–4.0 mils	1.3–1.6 mils
Benjamin Moore Ultra Spec EXT Satin (N448)	Exterior	350–450 sq ft	4.0 mils	1.5 mils
Benjamin Moore Aura Waterborne Exterior Satin (N631)	Exterior	250–350 sq ft	4.6–6.3 mils	2.0–2.7 mils
Benjamin Moore Regal Select Exterior High Build Low Lustre (N401)	Exterior	250–350 sq ft	5.3 mils	2.3 mils

Sources are listed at the end of the page. Every data sheet adds that the actual rate depends on surface texture and porosity.

Two patterns stand out. Interior wall paints from both makers cluster at 350–450 square feet. The exterior products split in two: a standard exterior satin lists 350–450, while the premium and high-build exteriors list 250–350 because they are designed to lay down a wet film up to about 1.6 times as thick.

Why film thickness sets the number

One U.S. gallon is 231 cubic inches. Spread at a wet thickness of one mil (0.001 inch), it would cover 231,000 square inches, or about 1,604 square feet. Every extra mil of thickness divides that area:

Coverage per gallon ≈ 1,604 ÷ wet film thickness in mils

Wet film	Theoretical coverage
3.2 mils	501 sq ft
4.0 mils	401 sq ft
5.3 mils	303 sq ft
6.3 mils	255 sq ft

The data sheets match the formula closely: a 4-mil product lists about 400 square feet, and a 5.3-mil product lists 250–350. This is a theoretical maximum on a smooth, sealed surface. Roller nap, texture, porosity, waste in trays and brushes, and spraying all reduce what you actually get. It also explains why “thick” premium paints can cover less area per gallon while hiding better per coat.

Turn the range into a purchase

The same wall can need very different amounts depending on where in the range your surface lands. For 391 square feet of measured wall and two coats:

Spread rate	Exact gallons	Whole packages
450 sq ft/gal	1.74	2 gal, or 1 gal + 3 qt
400 sq ft/gal	1.96	2 gal
350 sq ft/gal	2.23	2 gal + 1 qt
300 sq ft/gal	2.61	2 gal + 3 qt
250 sq ft/gal	3.13	3 gal + 1 qt

If your product lists a range, plan from the low end unless a test area shows the paint goes further. Textured, porous or freshly patched walls belong at or below the low end.

A practical order of work:

Measure each surface. Gross wall area is perimeter × height, minus the measured area of doors and windows. A ceiling is length × width. Trim is its own measured face area.
Read the selected product’s spread rate and the coat count you have tested or the label specifies.
Divide area × coats by coverage, then round up to the packages actually sold.
Enter gallon and quart prices separately. A quart rarely costs a quarter of a gallon, so compare real prices when deciding between three quarts and a gallon.

The paint calculator keeps wall, ceiling, primer and trim coverage as separate inputs, so you can run the low and high cases directly.

Walls and ceilings are separate orders

Walls and ceilings use the same formula on different measurements, and they are often different products. In a 14 × 16-foot room with 8-foot walls, the ceiling is 14 × 16 = 224 square feet. The walls are (14 + 16) × 2 × 8 = 480 square feet gross; with 60 square feet of doors and windows they are 420 square feet net.

At 350 square feet per gallon and two coats each:

Ceiling: 224 × 2 ÷ 350 = 1.28 gallons, which rounds to 1 gallon + 2 quarts
Walls: 420 × 2 ÷ 350 = 2.40 gallons, which rounds to 2 gallons + 2 quarts

Both orders total four gallons, but three gallons of wall paint and one of ceiling paint would leave the ceiling short. Ceiling paint is usually a flat, low-sheen product chosen to hide lap marks, and its label rate may differ from the wall paint’s, so calculate each line with its own coverage.

Primer is a separate product with its own rate

Primer seals porous surfaces such as bare drywall, joint compound and new wood. It also blocks stains, helps paint grip glossy or unknown coatings, and gives an even base for a large color change. If the surface is sound, clean, already painted with a compatible product and staying a similar color, the finish paint’s label may say no separate primer is needed. The product instructions decide, not a rule of thumb.

When you do prime, measure only the area that will be primed and use the primer’s own spread rate:

Primer gallons = primed area × primer coats ÷ primer coverage

At an illustrative 300 square feet per gallon, priming a 400-square-foot wall takes 400 ÷ 300 = 1.33 gallons, or 1 gallon + 2 quarts. Spot-priming 50 square feet of patches takes 0.17 gallon, which fits in a quart. Never borrow the finish paint’s coverage for primer.

“Paint and primer in one” products can skip a step over sound, similar-color walls. They do not seal raw drywall like a dedicated primer or guarantee a stain is blocked; read what the specific product claims for your surface.

Fix the cause of water stains and clean greasy surfaces before priming. For homes built before 1978, the EPA warns that sanding or scraping old paint can create hazardous lead dust. Visual inspection cannot confirm asbestos in older ceiling or wall materials either.

Coverage is not hiding: dark colors and coat count

A spread rate says how far a gallon goes at the designed thickness. It does not say whether one coat will hide navy under white. Hiding depends on both colors, the product’s pigment and base, the primer, film thickness, texture and lighting. Rules such as “dark to light always takes three coats” are folklore.

Test instead. Coat a representative patch with the exact system you plan to use, primer included. Let each layer dry for the time on the label, then inspect it in normal and raking light. Use the coat count that patch needed for the whole room. Then the gallons are ordinary math: for 333 square feet of net wall at 350 square feet per gallon, one coat is 0.95 gallon, two coats 1.90 and three coats 2.85. Each extra coat adds a whole gallon in this example, which is what a tinted primer may or may not save. Compare the full systems with real prices before assuming either is cheaper.

Leftover paint and touch-ups

Expected leftover is what you bought minus what you planned to use. If you buy 2 gallons and a quart (2.25 gallons) for a job estimated at 1.90 gallons, about 0.35 gallon should remain. The real amount will be less, because paint stays in the can, tray and roller.

Label anything you keep with the room, manufacturer, product line, color name and code, sheen, base and purchase date. Without that, the can is not useful touch-up paint. Store it as the manufacturer directs and test aged paint on a hidden spot before relying on it. Do not pour unwanted paint down a drain; the EPA directs households to state and local household hazardous waste and paint recycling programs.

Sources

Data sheets and agency pages were read on October 4, 2026.

Figures on this page are general-information estimates, not professional advice. Check the stated assumptions and any linked manufacturer or primary sources before buying materials.