Wall Math is not affiliated with Benjamin Moore. Every number below is copied from that company's own published data sheets and calculator page, with the date each was read.
Four of those documents publish a coverage figure, and between them they print two ranges, not one: 400 to 450 square feet per gallon on three of the four, and 350 to 400 on the other. So there is no single "Benjamin Moore number" to type into a calculator. There is the number on the can you are actually buying.
This guide does three things: it quotes what the maker's own calculator tells you it has already assumed, lines up the four published figures, and runs one room across the whole published span so you can see what the gap is worth. It does not compare this maker with any other, and it does not tell you which product to buy.
What their own calculator has already decided
Before the coverage figure matters, two assumptions do. The maker's paint calculator page states them plainly:
These calculations assume 2 coats of paint and do not include the ceiling.
Both halves are worth sitting with.
Two coats is an assumption, not a measurement of your wall. The same company's data sheet for Regal Select 550 says that on new or bare surfaces "two coats are required; previously painted surfaces can be finished with 1 or 2 coats." So the coat count is a property of your job — bare drywall, or a repaint in a similar color — and a calculator that fixes it at two is making a choice on your behalf. It is a sensible default and it is still a choice.
Not the ceiling is the one people miss. A ceiling is a different surface, bought as a different product, with its own coverage figure. If you take a whole-room square footage into a wall-paint calculator, you are asking the wrong can to cover it.
The calculator on this site makes the first assumption visible rather than fixed: coats is a field you set. The second it states under every result — "Ceiling, primer and trim are not included unless measured separately."
The four published figures
Each of these is quoted from the product's own technical data sheet, as printed.
| Product | Published coverage per gallon | Surface |
|---|---|---|
| Ultra Spec 500 Interior Eggshell N538 | 350 – 400 sq. ft. | walls |
| Regal Select Interior Pearl 550 | 400 – 450 Sq. Ft. | walls |
| Waterborne Ceiling Paint 508 | 400 – 450 Sq. Ft. | ceiling |
| Muresco Ceiling 258 | 400 – 450 Sq. Ft. | ceiling |
Three print the same range and one prints a lower one. That is the whole of the "four products, two numbers" in the title: four documents, two distinct ranges, and a published span running from 350 at the bottom to 450 at the top.
Both wall data sheets attach the same qualifier to their figure — "Depending on surface texture and porosity" — and the 550 sheet adds a line that reads like an instruction to do exactly what this site does: "Be sure to estimate the right amount of paint for the job."
One room across the whole span
Here is a room to hang the numbers on. Twelve by fourteen feet, eight-foot walls, with one door and two windows measured at 44.25 square feet in total.
The perimeter is 12 + 14 + 12 + 14 = 52 feet. Times 8 feet of height is 416 square feet of gross wall. Take off the 44.25 and you are painting 371.75 square feet.
Two coats, a 10 percent allowance, cans in gallons and quarts:
| Coverage figure | Gallons the arithmetic needs | What you buy |
|---|---|---|
| 350 sq ft/gal | 2.337 | 2 gallons + 2 quarts |
| 400 sq ft/gal | 2.045 | 2 gallons + 1 quart |
| 450 sq ft/gal | 1.817 | 2 gallons |
So the maker's entire published span, bottom to top, is two quarts on this room. That is smaller than people fear and larger than nothing, and which end you land on is decided by which product is in your cart and how thirsty your wall is.
The gap widens if your shop sells gallons only. Rounding the same three figures up to whole gallons gives 3, 3 and 2 — the bottom of the span and the top are a whole gallon apart, because a quart is no longer available to absorb the difference.
The two wall products overlap at exactly one number
Look again at the wall rows. Ultra Spec runs 350 to 400. Regal Select runs 400 to 450. They meet at 400 and only at 400.
That is a useful thing to know, because it means 400 is the one figure that is defensible for either product, and it is the midpoint of the published span. It is not a recommendation — your can decides, not the midpoint — but if you are standing in the shop with the sheet in front of you and no idea which end of the range your wall sits at, 400 is the number both documents will support.
What the overlap does not mean is that the two products behave alike. One sheet says 350 at its lower bound and the other says 450 at its upper. Spread across the room above, that is the full two-quart swing.
The ceiling is a separate can, and a separate number
Both ceiling products publish 400 to 450. The 508 sheet gives "Coverage per Gallon at Recommended Film Thickness 400 – 450 Sq. Ft."; the 258 sheet words it differently, "Spread Rate Per Gallon 400 – 450 Sq. Ft.", and adds that the maker "recommends two coats to achieve full color development."
The ceiling of the room above is 12 by 14, which is 168 square feet. Two coats with the same 10 percent allowance:
- at 400 sq ft/gal: 0.924 gallons → 1 gallon
- at 450 sq ft/gal: 0.821 gallons → 1 gallon
Here the published range changes nothing you buy. One gallon covers it either way, though not by much: less than a third of a quart to spare at 400, and about three-quarters of a quart at 450. That is worth knowing precisely because it is the opposite of the wall result: the same spread of published figures moved the wall order by two quarts and the ceiling order by nothing at all. Ranges matter when they straddle a can boundary and not otherwise.
What does change is that it is another can. Walls and ceiling in that room are roughly two and a half gallons of one product plus one gallon of a different one, and no single calculator run gives you both.
Which end of the range should you use
Neither sheet tells you. Both say the figure depends "on surface texture and porosity", which is a polite way of saying the manufacturer cannot see your wall.
What the arithmetic says is that the low end is the safe end. At 350 on the room above you buy 2 gallons and 2 quarts; if the wall then performs at 450 you have about two-thirds of a gallon left over. Start at 450, and if the wall performs at 350 you are a trip short in the middle of a second coat. The cost of being wrong is not symmetrical, and the allowance is there for the same reason.
The surfaces that sit at the low end are the ones you can usually spot before you start: fresh patching compound, a skim coat, a porous or chalky old finish, a texture with any relief to it, and any job where the new color is much lighter than the old one. A smooth, previously painted wall in a similar color is the case the top of the range is describing.
What to type in
The paint calculator takes the figure from your can in the field marked "Coverage on the label". Three things belong to you rather than to the manufacturer:
The coverage figure, read off the can or the sheet for the exact product and finish, not a rule of thumb and not a number from a different line by the same maker.
The coat count. Two if the color is changing or the surface is bare, which is what both the data sheet and the maker's calculator assume. One is a real option on a repaint in the same color, and two rooms and the coat question runs what that is worth.
The openings. The 44.25 above is a measurement, not a default. What belongs in the openings box shows how much it moves, which on one room is about a quart.
If you only have a wall square footage and want the can count without the arithmetic, the wall square feet to paint cans table reads it straight off at 350, 400 and 450, which are exactly the three figures above.
What this guide does not do
It does not rank this maker against any other. Several manufacturers publish coverage as a range and they do not agree; your can prints a range, not a number is where that comparison lives, and it is about the shape of published ranges rather than about whose paint is better.
It does not recommend a product, a finish or a retailer, and it carries no prices.
And it does not tell you what your wall will actually drink. Every figure above is the manufacturer's, measured at a recommended film thickness in a laboratory sense, and your wall is the test that matters.
The count in one line
Wall area − measured openings, × coats, ÷ the figure on your can, × 1.10, rounded up to the cans your shop sells.
For the room above that is 371.75 × 2 ÷ (350 to 450) × 1.10, which lands between 2 gallons and 2 gallons plus 2 quarts. Read your can before you decide which.
Sources
Every figure is quoted from the manufacturer's own data sheet or calculator page on the date given. Every gallon and quart figure was produced by the calculation engine behind this site's paint calculator on 2026-10-06.
- Benjamin Moore, paint calculator page: "These calculations assume 2 coats of paint and do not include the ceiling." https://www.benjaminmoore.com/en-us/paint-calculator (accessed 2026-09-09)
- Benjamin Moore, Regal Select Interior Pearl 550 technical data sheet (TDS US 073118): "Coverage per Gallon at Recommended Film Thickness 400 – 450 Sq. Ft. … Depending on surface texture and porosity. Be sure to estimate the right amount of paint for the job."; "…two coats are required; previously painted surfaces can be finished with 1 or 2 coats." https://media.benjaminmoore.com/WebServices/prod/assets/stage/datasheets/TDS_0550/20180731%20550%20TDS%20US%20OKF.pdf (accessed 2026-09-07)
- Benjamin Moore, Ultra Spec 500 Interior Eggshell N538 technical data sheet (TDS US 020419): "Coverage per Gallon at Recommended Film Thickness 350 – 400 sq. ft. … Depending on surface texture and porosity." https://media.benjaminmoore.com/WebServices/prod/assets/stage/datasheets/TDS_0538/20190204%20N538%20TDS%20US%20OKF.pdf (accessed 2026-09-07)
- Benjamin Moore, Waterborne Ceiling Paint 508 technical data sheet: "Coverage per Gallon at Recommended Film Thickness 400 – 450 Sq. Ft." https://media.benjaminmoore.com/WebServices/prod/assets/stage/datasheets/TDS_0508/20200210%20508%20TDS%20US%20OKF.pdf (accessed 2026-09-17)
- Benjamin Moore, Muresco Ceiling 258 technical data sheet: "Spread Rate Per Gallon 400 – 450 Sq. Ft."; "Benjamin Moore® recommends two coats to achieve full color development." https://media.benjaminmoore.com/WebServices/prod/assets/production/datasheets/TDS_0258/258_TDS_US.pdf (accessed 2026-09-17)