A gallon of interior paint covers 350 to 450 square feet, by most maker figures, counted as one coat. How many square feet does a gallon of paint cover for your product? Sherwin-Williams says roughly 350 to 400, while Benjamin Moore's Regal Select sheet says 400 to 450. Painted twice, a 15 ft 4 in by 12 ft 8 in room with 8 ft walls takes 2 gallons of Regal Select or 3 of 350 to 400 paint.
Table of Contents
Square feet per gallon by maker
The makers below print 250 to 450 square feet per gallon, and the low end of each range is the safer one to plan from. Benjamin Moore links the spread to surface texture and porosity, while Sherwin-Williams also points to how the paint is applied.
Add up the wall rectangles by hand or with the square footage calculator, then divide by your product's figure. Sherwin-Williams' paint calculator FAQ quotes 350 to 400 without naming a product, so treat it as a stand-in until you have a can in hand.
Square feet a gallon covers for each paint
Each row is the figure a maker prints for one US gallon. We count it as one coat, since Benjamin Moore and PPG print theirs beside one film thickness range.
| Maker | Product | Sq ft per gallon | Metric as printed |
|---|---|---|---|
| Sherwin-Williams | none named | about 350 to 400 sq ft | not given |
| Benjamin Moore | Regal Select Interior Satin/Pearl (N550) | 400 to 450 sq ft | not given |
| Benjamin Moore | Tough Walls Semi-Gloss (N22) | 400 to 450 sq ft | not given |
| PPG | Ultra-Hide 250 Gloss | about 350 to 400 sq ft | 32 to 37 m² per gallon |
| Behr | Premium Plus ceiling flat | 250 to 400 sq ft | 23 to 37 m² per gallon |
| Behr | Marquee Interior | up to 400 sq ft | not given |
PPG and Behr also print square meters per gallon, the column to use once you convert your wall area to square meters.
Square footage of a room for painting
For paint, a room's square footage means the surface you will roll, and that is almost never the floor number on a listing or plan. The floor number sets a trap. Square a 10 ft by 10 ft room and you get 100 square feet, which makes one gallon look like plenty. Stand that room's four walls up at 8 ft and they total 320 square feet before any opening, more than three times the floor.
A gallon rated 350 to 400 still covers those walls, but only once.
Typical room sizes are floor figures as well, useful for finding a perimeter or a ceiling area but never the walls. Order from the floor and you come up short. The room in the next section has 194 square feet of floor, and doubling that for two coats points to about 1 gallon when its walls need 2 or 3.
How do painters calculate square footage
Start from the net wall area, multiply by the coats, then divide by the label's coverage and round up to whole cans. The example follows that order on a 15 ft 4 in by 12 ft 8 in room with 8 ft walls, one door and two windows.
Get the net wall area
Walls running 56 ft around at 8 ft high make 448 square feet, and a door and two windows take 50, leaving 398 after measuring each wall and its openings.
Multiply the area by the coats
Two coats turn 398 square feet into 796 square feet of rolling. Skip this step and the order comes out at half of what the room needs.
Divide by the low end of the label
At 350 square feet per gallon, 796 needs 2.27 gallons. At 400 it needs 1.99.
Plan from 350. Two gallons spread at that rate reach only 700 square feet, so an order based on 400 can leave 96 square feet bare. That makes the buy 3 gallons, or 2 gallons plus 2 quarts. A single extra quart does not close the gap, because 2 gallons and a quart reach 787.5 square feet at 350.
At Regal Select's 400 to 450, the same walls need 1.77 to 1.99 gallons, and 2 gallons are enough.
One coat or two coats
Count two coats on any unpainted surface or whenever you want the color to come out full. Over sound paint that is already there, one or two will do. Benjamin Moore gives that advice on both its Regal Select and Tough Walls sheets. The Regal Select sheet also says that some custom colors need a deep-base primer tinted to match. Treat a one-coat label as the maker's claim for its own product, and still count the coats your wall needs.
Primer coverage per gallon
Divide primer by the primer's own label, which can read lower than the paint's. Sherwin-Williams' FAQ gives about 200 to 300 square feet per gallon. PPG's 2021 sheet for its Seal Grip High Hide primer gives about 300 to 400.
On the example's 398 square feet, one primer coat takes 1.33 to 1.99 gallons by the first range and 1.00 to 1.33 by the second. Work it out at the paint's 400 instead and you would buy 1 gallon where nearly 2 may be needed.
How many square feet will 5 gallons cover
Five gallons cover 1,750 to 2,000 square feet at 350 to 400 per gallon, or 2,000 to 2,250 at Regal Select's 400 to 450. Both figures count one coat, each per-gallon range multiplied by 5. A second coat halves them, because each 1 ft square of wall takes paint twice, so a bucket good for 1,750 square feet once covers 875 painted twice.
The table works each container out from the two per-gallon ranges, with 4 quarts to the gallon per the National Institute of Standards and Technology (NIST).
| Container and coats | At Sherwin-Williams' 350 to 400 sq ft per gallon | At Regal Select's 400 to 450 sq ft per gallon |
|---|---|---|
| 1 quart, one coat | 87.5 to 100 sq ft | 100 to 112.5 sq ft |
| 1 gallon, one coat | 350 to 400 sq ft | 400 to 450 sq ft |
| 5 gallons, one coat | 1,750 to 2,000 sq ft | 2,000 to 2,250 sq ft |
| 5 gallons, two coats | 875 to 1,000 sq ft of wall | 1,000 to 1,125 sq ft of wall |
Square footage of a quart of paint
Sherwin-Williams' FAQ puts a quart at 100 square feet. A quart is a quarter gallon, so at the 350 end of that same FAQ's gallon range it comes closer to 87.5. That gap is why the order above adds two quarts rather than one.
Why a gallon covers less than the printed figure
A printed figure can assume a better surface than your wall. PPG's Ultra-Hide 250 data sheet from 2015 shows how. Its 350 to 400 holds for smooth, nonporous surfaces and leaves out losses from texture, porosity, the way the paint goes on and mixing.
Thickness is the part you control, and the Regal Select numbers show why (our arithmetic on the 2025 sheet). A US gallon holds exactly 231 cubic inches, per NIST Handbook 44. Laid 1 mil (0.001 in) deep, it spreads over 231,000 square inches, about 1,604 square feet at 144 square inches to the square foot, if all of it stayed put. Only 38% of Regal Select by volume is solids, and the rest evaporates, so a 1 mil dry film reaches about 610. The Regal Select data sheet's recommended 1.3 to 1.5 mils dry brings that down to about 406 to 469, and a heavier coat goes less far still.
FAQ
How much paint for 1,000 square feet of wall?
At 350 to 400 square feet per gallon, 1,000 square feet of wall takes 2.5 to 2.86 gallons per coat. Buy 3 for one coat. Two coats need 5.0 to 5.71 gallons, so buy 6.
How much paint for an 1,800 sq ft house?
You can't size the order from 1,800 square feet, because a house's figure is floor area, taken around the outside walls as how a house's square footage is measured explains. Measure the walls and ceilings of the rooms you plan to paint, add them up and divide by your label.
How much paint do I need per square foot?
One square foot takes 1/350 to 1/400 of a gallon if Sherwin-Williams' range is one coat. A gallon is 128 fluid ounces by NIST's tables, which puts each square foot at about 0.32 to 0.37 fluid ounces a coat.
How far does a gallon of ceiling paint go?
Behr rates its Premium Plus ceiling flat at 250 to 400 square feet per gallon (23 to 37 m²). A flat ceiling matches the floor below it, so a 194 square foot ceiling takes 0.49 to 0.78 gallon, counting that range as one coat.
Conclusion
How many square feet does a gallon of paint cover in your room? Your product's low end, so divide your rolling area, coats included, by that figure. Swapping Regal Select for a 350 to 400 paint adds 2 quarts to the example room. That room's 194 square feet of floor is the figure to carry over if you measure the same room for flooring.
