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Paint coverage chart
Put your area, paint coverage and waste allowance in: 400 sq ft at 10% waste with 350 sq ft per gallon needs 1.26 gallons exact, order 2.
★ CONSTRUCTION · PAINT · COVERAGE CHART
Paint Coverage Chart: 2 Gallons for a 400 Sq Ft Room
On the defaults — a 400 sq ft room at 10% waste with 350 sq ft per gallon paint — you need 1.26 gallons exact: order 2 gallons. This is the FIXED-COVERAGE version — the lookup table at 350 sq ft per gallon across room sizes — the paint-coverage-chart page is the COVERAGE version — gallons per room at a coverage you set; the paint-cost-calculator page is the COST version — the same gallons priced per gallon; and the drywall-chart page is the SHEET version — the same waste-and-round-up model counted in sheets instead of gallons.
What does 1.26 gallons, order 2, mean?
It means that a 400 sq ft room, once a 10% waste allowance is added, needs 440 sq ft of paint coverage, and at 350 sq ft a gallon that is exactly 1.26 gallons — so you order 2 gallons, because a partial gallon cannot be bought in the quantity you need and the 0.26 of a gallon is real paint. The waste allowance is the whole story in miniature: without it the same room would need exactly 1.14 gallons, so the allowance is worth 0.12 gallons here, and ordering 1 gallon would leave about 90 sq ft — nearly a quarter of the room — unpainted. The part people get wrong is rounding the exact figure twice: 1.26 already includes the waste, so ordering 3 “just in case” adds a second, hidden allowance, and on a whole house that habit quietly buys a gallon too many on every order.
Three things to check before you trust the number
Is 350 sq ft really your paint’s coverage? Coverage is printed on the paint can and varies by product, surface and coat: a typical interior latex covers about 350 sq ft a gallon, but a rough or porous surface can drop it well below that. The 250-coverage branch needs 1.76 gallons, order 2, so a wrong coverage figure can still land on the same order — but on a bigger room it moves the order by whole gallons. Read the can, and use the figure for your surface, not a generic one.
Is 10% waste enough for your room? Ten percent covers straightforward walls with ordinary cutting in, but rooms full of trim, doors, windows and odd angles can push real waste to 15% or 20%, and every extra 10% on 400 sq ft is another 40 sq ft, or about 0.11 gallons. The 800 sq ft branch orders 3 gallons, so on a large area a waste error compounds fast. If your room is cut up, price the job at 15% waste first and compare.
Are you painting one coat or two? This page counts one coat over the area you enter. Two coats double the gallons: two coats over 400 sq ft need 2.51 gallons exact, order 3, not 2, and the lookup table below is per coat. If your job needs two coats, run the page once per coat or double the order — do not let a single-coat figure order half a job.
Worked example
On the defaults: 400 sq ft area, 350 sq ft per gallon coverage, 10% waste allowance.
- Needed coverage: 400 × 1.10 is 440 sq ft.
- Exact gallons: 440 ÷ 350 is 1.26 gallons.
- Order: 1.26 rounded up is 2 gallons — a partial gallon cannot be bought in the quantity needed, so the 0.26 is a whole gallon.
And the other way: the area needing exactly 1.26 gallons at 350 sq ft a gallon is 400 sq ft, the coverage needing exactly 1.26 gallons over 400 sq ft is 350 sq ft per gallon, and the area needing exactly 2.51 gallons at 350 sq ft a gallon is 800 sq ft.
Every branch, checked
- 200 sq ft area, 350 sq ft per gallon: 200 sq ft area, 350 sq ft per gallon: 0.63 gallons exact — order 1 gallons.
- 800 sq ft area, 350 sq ft per gallon: 800 sq ft area, 350 sq ft per gallon: 2.51 gallons exact — order 3 gallons.
- 400 sq ft area, 250 sq ft per gallon: 400 sq ft area, 250 sq ft per gallon: 1.76 gallons exact — order 2 gallons.
- 400 sq ft area, 0% waste: 400 sq ft area, 0% waste: 1.14 gallons exact — order 2 gallons.
- 100 sq ft area, 350 sq ft per gallon: 100 sq ft area, 350 sq ft per gallon: 0.31 gallons exact — order 1 gallons.
- 1,000 sq ft area, 350 sq ft per gallon: 1,000 sq ft area, 350 sq ft per gallon: 3.14 gallons exact — order 4 gallons.
The reverses, worked backwards
- Area needing exactly 1.26 gallons at 350 sq ft a gallon: 400 sq ft — at 400 sq ft the figures are 1.26 gallons exact — order 2 gallons.; at the lower neighbor the figures are 1.10 gallons exact — order 2 gallons.; at the upper neighbor the figures are 1.41 gallons exact — order 2 gallons..
- Coverage needing exactly 1.26 gallons over 400 sq ft: 350 sq ft per gallon — at 350 sq ft per gallon the figures are 1.26 gallons exact — order 2 gallons.; at the lower neighbor the figures are 1.47 gallons exact — order 2 gallons.; at the upper neighbor the figures are 1.10 gallons exact — order 2 gallons..
- Area needing exactly 2.51 gallons at 350 sq ft a gallon: 800 sq ft — at 800 sq ft the figures are 2.51 gallons exact — order 3 gallons.; at the lower neighbor the figures are 2.36 gallons exact — order 3 gallons.; at the upper neighbor the figures are 2.67 gallons exact — order 3 gallons..
What the defaults assume
The defaults are a 400 sq ft area, 350 sq ft per gallon coverage and a 10% waste allowance, so the headline is a single room painted in one coat with a typical interior latex. The model is a multiplication, a division and a ceiling: needed coverage is area times 1.10, exact gallons are needed coverage divided by paint coverage, and the order rounds exact gallons up to the next whole gallon, with a 1e-12 epsilon so an exact whole number orders exactly that many. The area reverse is checked at 50 sq ft either side, because 50 sq ft times 1.10 over 350 sq ft is about 0.16 gallons; the coverage reverse is checked at 50 sq ft either side, because 440 over 300 is 1.47 gallons and over 400 is 1.10; the 800 sq ft reverse is checked at 50 sq ft either side, because 50 sq ft times 1.10 over 350 sq ft is about 0.16 gallons. The model does not include offcut reuse, second coats, primer, ceiling waste from texture, or brush and roller quantities — count those separately.
Lookup table: gallons by room size
Each row already includes the 10% waste allowance: needed coverage is the area times 1.10, exact gallons are needed coverage divided by 350 sq ft per gallon, and the order column rounds up. A row that lands exactly on a whole number orders exactly that many — no extra gallon is added for an exact fit.
| Area | Paint coverage | Needed coverage | Exact gallons | Order |
|---|---|---|---|---|
| 100 sq ft | 350 sq ft per gallon | 110 sq ft | 0.31 | 1 gallons |
| 150 sq ft | 350 sq ft per gallon | 165 sq ft | 0.47 | 1 gallons |
| 200 sq ft | 350 sq ft per gallon | 220 sq ft | 0.63 | 1 gallons |
| 250 sq ft | 350 sq ft per gallon | 275 sq ft | 0.79 | 1 gallons |
| 300 sq ft | 350 sq ft per gallon | 330 sq ft | 0.94 | 1 gallons |
| 350 sq ft | 350 sq ft per gallon | 385 sq ft | 1.10 | 2 gallons |
| 400 sq ft | 350 sq ft per gallon | 440 sq ft | 1.26 | 2 gallons |
| 450 sq ft | 350 sq ft per gallon | 495 sq ft | 1.41 | 2 gallons |
| 500 sq ft | 350 sq ft per gallon | 550 sq ft | 1.57 | 2 gallons |
| 600 sq ft | 350 sq ft per gallon | 660 sq ft | 1.89 | 2 gallons |
| 700 sq ft | 350 sq ft per gallon | 770 sq ft | 2.20 | 3 gallons |
| 800 sq ft | 350 sq ft per gallon | 880 sq ft | 2.51 | 3 gallons |
| 900 sq ft | 350 sq ft per gallon | 990 sq ft | 2.83 | 3 gallons |
| 1,000 sq ft | 350 sq ft per gallon | 1,100 sq ft | 3.14 | 4 gallons |
| 1,200 sq ft | 350 sq ft per gallon | 1,320 sq ft | 3.77 | 4 gallons |
| 1,500 sq ft | 350 sq ft per gallon | 1,650 sq ft | 4.71 | 5 gallons |
Output · formula · meaning
| Output | Formula | What it means |
|---|---|---|
| Needed coverage | area × 1.10 | 440 sq ft — 400 × 1.10. |
| Exact gallons | needed coverage ÷ paint coverage | 1.26 gallons — 440 ÷ 350. |
| Order | exact gallons rounded up | 2 gallons — 1.26 rounds up. |
| Area needing exactly 1.26 gallons | needed coverage ÷ 1.10 | 400 sq ft — 440 ÷ 1.10. |
| Coverage needing exactly 1.26 gallons | needed coverage ÷ exact gallons | 350 sq ft per gallon — 440 ÷ 1.2571. |
| Area needing exactly 2.51 gallons | needed coverage ÷ 1.10 | 800 sq ft — 880 ÷ 1.10. |
| 200 sq ft area, 350 sq ft per gallon | same model | 0.63 gallons exact — order 1 gallons. |
| 800 sq ft area, 350 sq ft per gallon | same model | 2.51 gallons exact — order 3 gallons. |
| 400 sq ft area, 250 sq ft per gallon | same model | 1.76 gallons exact — order 2 gallons. |
| 400 sq ft area, 0% waste | same model | 1.14 gallons exact — order 2 gallons. |
| 100 sq ft area, 350 sq ft per gallon | same model | 0.31 gallons exact — order 1 gallons. |
| 1,000 sq ft area, 350 sq ft per gallon | same model | 3.14 gallons exact — order 4 gallons. |
| Area needing exactly 1.26 gallons at 350 sq ft a gallon | reverse | 400 sq ft: 1.26 gallons exact — order 2 gallons. |
| Coverage needing exactly 1.26 gallons over 400 sq ft | reverse | 350 sq ft per gallon: 1.26 gallons exact — order 2 gallons. |
| Area needing exactly 2.51 gallons at 350 sq ft a gallon | reverse | 800 sq ft: 2.51 gallons exact — order 3 gallons. |
| 0 sq ft area | same model | 0.00 gallons exact — order 0 gallons. |
| Negative area | same model | Area — 0 or more. |
| 0 sq ft per gallon coverage | same model | Paint coverage — more than 0. |
| 400 sq ft area, 440 sq ft per gallon | same model | 1.00 gallons exact — order 1 gallons. |
Who uses this
- A DIYer painting a room — 400 sq ft at 10% waste with 350 sq ft per gallon is 2 gallons, with the lookup table covering every other room size without re-measuring.
- A contractor ordering for a job — the branches show how the order moves with area and coverage, so a paint substitution from 350 to 250 sq ft per gallon is repriced before ordering.
- A homeowner comparing paints — the 250-coverage branch shows whether the cheaper paint actually saves gallons or just changes the rounding.
- An estimator checking a quote — the reverses recover the area or coverage behind any quoted gallon count, which checks a quote without re-measuring the job.
Accuracy & limitations
Figures are the model’s own arithmetic on the numbers you type, computed from unrounded values and displayed rounded HALF_UP to 2dp, with orders rounded up using a 1e-12 epsilon so exact fits are not over-ordered. The main limitation is the coverage and waste figures, not the arithmetic: rough surfaces cover less per gallon, and cut-up rooms waste more than 10%, so check the paint can. This page is a calculation tool, not decorating advice — follow the paint maker’s instructions for preparation and coats.
Cite this calculator
A 400 sq ft room at 10% waste with 350 sq ft per gallon paint needs 1.26 gallons exact: order 2 gallons. Source: Bright Side Kit, https://brightoolbox.com/paint-chart/, accessed 29 October 2026.
Frequently asked questions
How do I find a paint’s coverage?
Read the can: coverage in square feet per gallon is printed on the label, and a typical interior latex is about 350 sq ft a gallon. If the label gives a range, use the figure for your surface — smooth walls cover more, rough or porous surfaces cover less.
Why 10% waste?
Ten percent is the standard allowance for cutting in, touch-ups, spills and roller absorption on straightforward walls. Straight, unobstructed walls waste less; rooms full of trim and openings waste more — price cut-up rooms at 15% or higher.
What if the exact figure is already a whole number?
Then you order exactly that many: 1.00 gallon orders 1, not 2. The waste allowance is already inside the exact figure, so adding another gallon for luck double-counts the allowance. The 440-coverage edge shows this: 440 divided by 440 is exactly 1.00, order 1.
Do I double the order for two coats?
Yes: this page counts one coat. Two coats over the same area need twice the gallons, so a 400 sq ft room painted twice orders 3 gallons, and the lookup table below is per coat.
What about ceilings — is the waste the same?
Ceilings often waste more than walls, because texture and overhead rolling use more paint, and cutting in overhead is slower. If your ceiling is textured, price it at 15% waste first and compare with the 10% figure before ordering.
What about primer?
Primer is a separate coat with its own coverage, usually higher than topcoat coverage. Price primer on its own: run this page with the primer’s coverage figure and the primed area, and do not count primer gallons as topcoat gallons.