Chapter 02Paint · Know-how
One coat or two? How to read the coverage line on a paint can
The coverage line on a can, such as 400 to 450 sq ft per gallon, is for one coat on a smooth surface. Two coats use twice the paint. Benjamin Moore recommends at least two coats for full hide and color, and says previously painted walls can sometimes be finished in one or two. Sherwin-Williams calls the per-gallon figure theoretical, so real walls usually get less. In the paint calculator's bedroom, one coat is about 0.8 to 1.1 gallons and two coats about 1.7 to 2.1.
Source: Benjamin Moore Regal Select (matte) product page, checked October 5, 2026; Benjamin Moore, how to paint interior walls, checked October 17, 2026; Benjamin Moore, paint and primer in one, checked October 17, 2026; Sherwin-Williams painting FAQs, checked October 17, 2026.
- What the per-gallon coverage figure is for1 coat Sherwin-Williams paint calculator, October 10, 2026
- Sq ft per gallon, one coat, in published figures for walls350 to 450 Sherwin-Williams paint calculator, October 10, 2026; Benjamin Moore Regal Select (matte) product page, October 5, 2026
- Benjamin Moore's recommendation for full hide and color2 coats Benjamin Moore, how to paint interior walls, October 17, 2026
What the coverage line means
Paint makers give coverage in square feet per gallon, for one coat. Sherwin-Williams' paint calculator assumes about 350 sq ft per gallon for walls and 400 for ceilings, trim and doors, each for one coat. Benjamin Moore lists 400 to 450 sq ft per gallon for its Regal Select matte. Many cans and product pages give a range like that.
Source: Sherwin-Williams paint calculator, checked October 10, 2026; Benjamin Moore Regal Select (matte) product page, checked October 5, 2026.
- Per gallon: a quart covers a quarter of the figure.
- One coat: two coats need twice the paint for the same wall.
- A range: plan on the low end, the fewest square feet, so you don't run short.
- Theoretical: Sherwin-Williams says the figure leaves out surface texture and paint left on rollers and brushes.
Source: Sherwin-Williams paint calculator, checked October 10, 2026; Sherwin-Williams painting FAQs, checked October 17, 2026.
How many coats does a wall need?
Benjamin Moore's how-to for interior walls recommends at least two coats of the top coat for hide and color development, and says to wait until the first coat is completely dry, using the dry time on the can. On its paint-and-primer products it is more specific: two coats on bare surfaces, and one or two on surfaces that are already painted.
Source: Benjamin Moore, how to paint interior walls, checked October 17, 2026; Benjamin Moore, paint and primer in one, checked October 17, 2026.
Plan for two
Buy for two coats unless you have a reason not to. Two is the default in Benjamin Moore's how-to.
One may do when
The wall is already painted, in good shape, and the new color is close to the old one. Benjamin Moore allows one or two coats on painted surfaces for its paint-and-primer lines.
Two or more when
The wall is bare drywall or a patch, or the color change is big. Benjamin Moore points to a primer for a big change.
Decide after the first coat dries
Wait the dry time on the can, then look in daylight. Patchy color or the old color showing through means a second coat.
Source: Benjamin Moore, how to paint interior walls, checked October 17, 2026; Benjamin Moore, paint and primer in one, checked October 17, 2026.
Primer is its own line
If you prime, the primer has its own coverage figure on its own can. Count it as a separate coat in the calculator, at that figure.
What a second coat costs in paint
Take the calculator's worked bedroom: 12 by 14 ft, 8 ft walls, one door and two windows, so 372 sq ft of wall. One coat at 350 to 450 sq ft per gallon is 0.83 to 1.06 gallons; the calculator rounds the buy up to 1 gallon and 1 quart. Two coats is 744 sq ft, 1.65 to 2.13 gallons, and the buy is 2 gallons and 1 quart.
Source: Sherwin-Williams paint calculator, checked October 10, 2026; Benjamin Moore Regal Select (matte) product page, checked October 5, 2026.
So in a typical bedroom the second coat is one more gallon. If you buy for one coat and need a second, you are back at the store for a can that has to match the first. Buying for two and having a gallon left over is usually the cheaper mistake.
Let the tool do the arithmeticPaint coverage calculatorPut in the room, set the coats to one or two, and enter the coverage range from your can. The calculator gives the gallons for each and rounds the buy up to the next quart.Example: Buy 2 gallons and 1 quart (12 x 14 ft room, 2 coats)Open the toolWrite the coverage on your paint record
When the room is done, write the product, color, sheen, the coverage figure on the can, how many coats you used and how much was left. Benjamin Moore suggests labeling stored paint with the brand, color, type, sheen and where it was used. Next time, the record tells you whether your walls got the low or the high end of the range.
Source: Benjamin Moore: storing leftover paint, checked October 10, 2026.
Checklist to print
Fill this in before you buy:
- Coverage figure from the can or product page (sq ft per gallon)
- Is it a range? Write the low end
- Wall is bare, patched, or already painted
- Color change: close to the old color, or a big change
- Primer needed? Its own coverage figure
- Coats planned (two unless there's a reason for one)
- Gallons from the calculator, rounded up to the quart
- Dry time from the can, before the second coat
- Coats used and paint left, written on the paint record
Tips and tricks
- Tip 01
Read the quart can too
Coverage is per gallon even on a quart label. A quart covers a quarter of the figure, which is about one coat on a small bathroom wall or a door.
- Tip 02
Thin coats, not one thick one
This Old House suggests several thin layers rather than a single thick coat, to avoid drips and buildup. A thick first coat doesn't save the second.
Source: This Old House, how to roll-paint a wall (boxing your paint), checked October 17, 2026.
- Tip 03
Use your own past numbers
If your paint record says the last room took the low end of the range, put that figure in the calculator for the next room in the same house.
- Tip 04
Check in daylight
Look at the first coat in daylight from the window side. Lamp light at night hides patchy spots that show the next morning.
What we would do
Buy for two coats, decide after one
Read the coverage line as square feet per gallon for one coat, take the low end of the range, and buy for two coats. Paint the first coat, let it dry for the time on the can, and look in daylight. If it covers evenly on an already painted wall, keep the rest for touch-ups.
Questions
Is the coverage on a paint can for one coat or two?
One coat. Sherwin-Williams' calculator gives its per-gallon figures for one coat, so two coats need twice the paint.
Source: Sherwin-Williams paint calculator, checked October 10, 2026.
Do I need two coats of paint?
Usually. Benjamin Moore recommends at least two coats for full hide and color. On walls that are already painted, its paint-and-primer products can finish in one or two.
Source: Benjamin Moore, how to paint interior walls, checked October 17, 2026; Benjamin Moore, paint and primer in one, checked October 17, 2026.
Is one gallon of paint enough for two coats on a bedroom?
Usually not. The calculator's 12 by 14 ft bedroom with 8 ft walls needs about 1.7 to 2.1 gallons for two coats.
Source: Sherwin-Williams paint calculator, checked October 10, 2026; Benjamin Moore Regal Select (matte) product page, checked October 5, 2026.
Why did I get less coverage than the can says?
Sherwin-Williams says the per-gallon figure is theoretical: it leaves out surface texture and paint left on the roller and brush. Rough or porous walls take more.
Source: Sherwin-Williams painting FAQs, checked October 17, 2026.
How long do I wait between coats?
Use the dry time printed on the can. Benjamin Moore says to wait until the first coat is completely dry.
Source: Benjamin Moore, how to paint interior walls, checked October 17, 2026.
The tool and more guides
Chapter 02Paint coverage calculatorWork out how many gallons of paint a room needs from its size, doors, windows and coats, using coverage figures published by paint makers.Open the tool
Problem-solving guideHow much paint do I really need?Work out gallons from wall area, coats and the coverage on the label, and see why a can runs out before the wall is done.Read the guide
Know-howHow much paint for a ceiling, trim and doorsMeasure a ceiling, baseboards, casings and doors in square feet, then turn them into gallons and quarts. With a 12 x 14 ft bedroom worked through.Read the guide- Chapter 02All paint toolsPaint quantity tools built on coverage figures published by paint makers, plus a printable record of colors, codes and leftover cans.Open the chapter
Sources
- Regal Select Interior Paint - Matte, Benjamin Moore. Checked October 5, 2026.
- How To Paint Interior Walls In 7 Easy Steps, Benjamin Moore. Checked October 17, 2026.
- Paint and Primer In One, Benjamin Moore. Checked October 17, 2026.
- Painting FAQs, Sherwin-Williams. Checked October 17, 2026.
- Paint Calculator, Sherwin-Williams. Checked October 10, 2026.
- 6 Tips For Storing Leftover Paint & Shelf Life, Benjamin Moore. Checked October 10, 2026.
- How To Roll-Paint a Wall Like a Pro, This Old House. Checked October 17, 2026.
Every outside number on this page names its source and the date we checked it. See them all on the sources page. Spotted an error? Tell us.