Paint Coverage Per Gallon: Chart and Calculator

Quick answer: One gallon of interior paint typically covers 350 to 400 square feet for one coat on a prepared surface. Put the other way, that is about 0.0025 to 0.0029 gallon of paint per square foot for one coat, or about 0.005 to 0.0057 gallon per square foot for two coats. One quart covers about 100 square feet. Primer often covers less, with Sherwin-Williams giving a general planning range of 200 to 300 square feet per gallon. The label for your chosen product is the final authority because coverage changes with the coating, surface, color, and application.

Source check: September 2, 2026. Coverage figures were checked against the Sherwin-Williams Paint Calculator FAQs and current manufacturer product information. This guide provides planning estimates, not a product guarantee.

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Paint Coverage Per Gallon Chart

Coating or container	Planning coverage	Best use
1 gallon of finish paint	350 to 400 sq. ft. per coat	Prepared, relatively smooth interior surfaces
1 quart of finish paint	About 100 sq. ft. per coat	Accent areas, doors, or small touch-up projects
1 gallon of primer	About 200 to 300 sq. ft. per coat	Bare, repaired, stained, or porous surfaces
2 coats from 1 gallon of finish paint	About 175 to 200 sq. ft. total project area	Divide one-coat coverage by two

The two-coat row does not mean the paint changes. It means the same surface is covered twice. If a gallon covers 400 square feet for one coat, it covers about 200 square feet of wall area when that wall receives two coats.

The Paint Coverage Formula

Gallons needed = paintable square feet × number of coats ÷ coverage listed on the paint label

How many gallons of paint per square foot? Using the common planning range of 350 to 400 square feet per gallon, one coat uses about 0.0025 to 0.0029 gallon per square foot, or roughly 0.25 to 0.29 gallon per 100 square feet. For two coats, double those amounts. Use the coverage printed on your paint label when it differs from the planning range.

Measure each wall’s width and height, then multiply width by height.
Add the square footage of all walls you plan to paint.
Subtract large doors, windows, cabinets, tile, or other areas that will not be painted.
Multiply the paintable area by the number of coats.
Divide by the coverage rate printed on the product label.
Add a waste allowance that fits the surface and project, then choose available container sizes.

The Cardinal Decor Paint Calculator handles the wall measurements, doors, windows, coats, label coverage, waste allowance, estimated paint cost, and rounded purchase quantity.

Check out our painting resources page for more project pricing guides, how-to articles, DIY FAQs, and free paint calculator tools.

Worked Paint Coverage Examples

Project	Paintable area	Coats	Calculated need
12 × 8 ft. accent wall	96 sq. ft.	1	0.24 to 0.27 gal.; a quart may be enough if the label lists about 100 sq. ft. of coverage
12 × 8 ft. accent wall	96 sq. ft.	2	0.48 to 0.55 gal.; plan on 1 gallon
12 × 14 × 8 ft. room	365 sq. ft. after subtracting one 21-sq.-ft. door and two 15-sq.-ft. windows	2	1.83 to 2.09 gal. before waste; choose 2 or 3 gallons based on the label and desired reserve
12 × 14 ft. ceiling	168 sq. ft.	2	0.84 to 0.96 gal.; plan on 1 gallon

For the room example, the wall area is 2 × (12 + 14) × 8, or 416 square feet. After subtracting 51 square feet for openings, the paintable area is 365 square feet. Two coats equal 730 square feet of coverage. Dividing by a label rate of 350 to 400 square feet per gallon produces 1.83 to 2.09 gallons before waste.

Why Your Paint May Cover Less Than the Estimate

The surface is porous or newly repaired

Bare drywall paper, joint compound, masonry, unsealed wood, and some repaired areas absorb coating unevenly. Prime where the product instructions call for it. A separate primer estimate is more honest than assuming a paint-and-primer label removes every preparation step.

The wall is textured

Texture adds surface area and makes it harder for a roller to reach every recess. Use a conservative coverage input and the roller nap specified for the surface. Avoid applying one universal percentage penalty because texture depth varies.

The color change needs more coats

Large shifts between dark and light colors, vivid colors, and some deep-base formulas may need extra coats or a tinted primer. Do not treat a one-coat claim as universal. Behr, for example, limits its MARQUEE one-coat guarantee to designated colors and stated application conditions.

The application method changes material use

Brushes, rollers, and sprayers place paint differently. Overspray, transfer loss, roller loading, back-rolling, and surface profile can all affect the amount used. Base the estimate on the product data and the method you will actually use.

The project includes trim, doors, or ceilings

Calculate each coating separately. Wall paint, ceiling paint, trim enamel, and primer may have different coverage rates and container sizes. Combining them into one gallon total can produce a misleading shopping list.

When to Use Primer

Bare drywall, fresh joint compound, or repaired patches
Porous or unevenly sealed surfaces
Water, smoke, tannin, ink, or other stains when the primer is rated for that stain
Glossy surfaces when the coating system calls for bonding primer
Large color changes or deep finish colors when a tinted primer is recommended

Primer coverage is product-specific. Sherwin-Williams gives a general 200-to-300-square-foot range, while one current Behr interior stain-blocking primer lists 250 to 400 square feet per gallon. Use the exact label rather than forcing every primer into one number.

How Much Extra Paint Should You Buy?

Start with the calculated amount, then decide how much reserve the job deserves. A simple, smooth room painted with a familiar product needs less protection against surprises than a textured wall, porous repair, spray application, complicated layout, or color with uncertain hide.

The calculator lets you select a waste allowance. Before buying another full gallon, check whether the product is sold in quarts. A project that calculates to 2.14 gallons may be served by two gallons and one quart, while a homeowner who wants future touch-up paint may prefer three gallons from the same batch.

Paint Buying Checklist

Measure walls, ceilings, doors, and trim separately.
Subtract only openings large enough to matter.
Choose the paint before accepting a default coverage rate.
Enter the coverage printed on the label or technical data sheet.
Estimate primer separately from finish paint.
Count the planned coats for each surface.
Add a project-appropriate waste allowance.
Check gallon and quart sizes before rounding.
Keep the formula, color code, sheen, room, and purchase date with leftover paint.

Next, use the paint calculator, review wall preparation, or check the drywall repair and painting cost guide. The Painting Resources hub connects the full planning path.

Paint Coverage Questions

How many square feet does one gallon of paint cover?

A common planning range is 350 to 400 square feet for one coat on a prepared surface. Check the product label and reduce the coverage input when the surface or application calls for it.

How much wall area can one gallon cover with two coats?

About 175 to 200 square feet, based on the common 350-to-400-square-foot one-coat range.

Does a 10 × 10 room equal 100 square feet of paint?

No. A 10 × 10 floor is 100 square feet, but wall area depends on perimeter and height. With an 8-foot ceiling, four 10-foot walls total 320 square feet before subtracting doors and windows.

Should I subtract every door and window?

Subtracting large openings improves precision. For a small project, leaving minor openings in the calculation can act as a modest reserve. Keep the method consistent and do not subtract trim if it will receive a separate coating.

Can one-coat paint cut the estimate in half?

Only when the chosen product, color, surface preparation, application rate, and guarantee conditions support one-coat coverage. Plan from the label and the condition of your wall, not the phrase alone.