How much paint do I need to paint the exterior of a 2000 square foot house?

Floor area is the wrong input. A 40 by 28 ft two-storey house is about 2,240 sq ft of floor and about 2,572 sq ft of paintable surface once the four wall faces, two gables and the trim are counted and the doors and windows come out. At Duration's published 250 sq ft per gallon less a 10% allowance that is 11.4 gal a coat, so about 23 gallons for two coats.

How do I calculate the area of a gable?

Half the base times the rise. The base is the width of the gable-end wall and the rise is from the top of the wall plate to the ridge. A 28 ft wall with a 7 ft rise gives 98 sq ft. The rise depends entirely on the roof pitch, so measure it rather than assume it: a 12:12 gable is three times a 4:12 gable on the same house.

Why does one exterior paint cover 400 sq ft and another only 250?

Because they are specified at different film thicknesses, not because one is thinner paint. SuperPaint Exterior is 4 mils wet and Duration is 5.3 to 6.4. Divide 1,604 by each and you get the published figures exactly. Duration leaves 2.2 to 2.7 mils of dry film against SuperPaint's 1.5, so you are buying more coating and putting more on the wall.

Do I need to deduct windows and doors on an exterior estimate?

Yes, deduct the opening. Two doors and fourteen windows on the worked example is 208 sq ft, about 8% of the wall. Do not deduct the trim around them if you are painting it, because that goes into the trim quantity instead.

What do I use on bare concrete block?

A block filler before the topcoat, not more topcoat. Sherwin-Williams' PrepRite block filler goes on at 16 mils wet and publishes 75 to 125 sq ft per gallon, roughly a quarter of a topcoat's coverage, and leaves 7.7 mils of dry film. It is filling the holes in the block rather than colouring it.

How much extra should I allow for spraying?

More than the 10% default here, which is a brush and roller figure. No manufacturer publishes a spray allowance, so raise the field until it matches what you have actually seen. Overspray, wind and the paint left in the hose and pump all come off the top.

Does lap siding need more paint than flat siding?

It has more surface, because every course has an exposed butt edge that a flat measurement does not count, and the same is true of rough sawn cedar and stucco. No data sheet publishes a multiplier for any of it. If the texture is pronounced, paint one wall and measure what it took rather than trusting a factor somebody invented.

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Gables counted as half base times rise. Coverage from Sherwin-Williams data sheets

The gable is where an exterior estimate goes wrong. It is the one piece of wall you cannot reach with a tape from the ground, so it gets guessed or skipped, and on a house with a steep roof it can be a fifth of the wall. This counts the faces, the gables and the trim separately, then sizes the order from a coverage figure it shows you the arithmetic for.

Exterior paint quantity

Paint

Coats

Bare masonry primer

House length (long side)

House width (the gable end)

Storeys

Wall height per storey

Gable ends

no.

Gable rise (wall plate to ridge)

Exterior doors (36 x 80 in each)

no.

Windows

no.

Window width

Window height

Trim, soffit and fascia (linear ft, 0 for none)

Trim girth (the width you actually coat)

Waste allowance (ours, not the maker's)

Coverage from your can (optional, overrides)

sq ft/gal

Coverage comes from the manufacturer's product data sheet, named in the table below. Two products with very different published rates are offered on purpose: compare what they do to the answer.

Specification summary

Generated from on . Reopen that address to reproduce these figures exactly.

Entered

Result

One gable end, drawn to scale

Worked example

A 40 ft by 28 ft two-storey house with 9 ft walls, two gable ends rising 7 ft, two doors, fourteen 3 ft by 4 ft windows, and 136 ft of soffit and fascia at a 12 in girth, in Duration Exterior Acrylic Flat, two coats, at the default 10% allowance.

Wall faces. Perimeter 2 × (40 + 28) = 136 ft, wall 2 × 9 = 18 ft, so 2,448 sq ft.
Gables. Half of 28 × 7 is 98 sq ft each, two of them: 196 sq ft. That is 8% on top of the walls, and it is all above the second-floor plate.
Openings. Two doors at 20 sq ft, fourteen windows at 12: 208 sq ft out.
Trim. 136 ft of soffit and fascia at 12 in girth is another 136 sq ft, and it is usually a different can.
Total. 2,448 + 196 − 208 + 136 = 2,572 sq ft a coat.
Paint. Duration publishes 250 to 300. Sizing from 250 less 10% gives 225 sq ft per gallon, so 11.4 gal a coat and 22.9 gal for two.

Now switch the product to SuperPaint Exterior Latex Flat, which publishes 350 to 400. The same house drops from 23 gallons to 17. That is not one paint going further than the other in any useful sense: it is Duration being specified at 5.3 to 6.4 mils wet against SuperPaint's 4, a thicker film on the wall. Compare the coverage figures and you compare the film thicknesses, whether you meant to or not.

The formula

Four areas, and the second one is the reason this page exists:

A = 2(L + W)h + g(Wr/2) − openings + t w/12 gallons = A n / (c (1 − k))

L, W: footprint length and width, ft. W is the gable-end wall
h: wall height, storeys times the height of each, ft
g, r: number of gable ends and the rise from wall plate to ridge, ft. A gable is half its base times its rise
t, w: trim and fascia, linear ft, and the girth you actually coat, in
n: coats. Coverage is published per coat, never for the job
c: published coverage, sq ft per gallon, from the data sheet
k: waste allowance. Ours, defaulting to 0.10, and no manufacturer publishes one

The gable term is the one worth checking on your own house. Half base times rise assumes a symmetrical gable, which most are. A saltbox, a shed dormer or a hip end is not, and a hip roof has no gable at all: set the count to zero and the wall term already has everything.

Why the two products differ by six gallons on the same house

Duration publishes 250 to 300 sq ft per gallon. SuperPaint Exterior publishes 350 to 400. On the worked example that is 23 gallons against 17, and the obvious reading is that one paint goes further.

It is not the reading the sheets support. Duration is specified at 5.3 to 6.4 mils wet and SuperPaint at 4. Run each through 1,604 divided by the wet film and both published figures fall straight out: 251 and 303 for Duration, 401 for SuperPaint. The coverage difference is a film thickness difference, printed plainly on both documents.

A thicker film is not waste. It is more dry material on the wall, which is what an exterior coating is for. Duration leaves 2.2 to 2.7 mils dry against SuperPaint's 1.5, so on the same wall you are buying roughly half again as much coating and getting roughly half again as much film. Whether that is worth the money is a judgement about the wall, the exposure and how long you want to wait before doing it again, and no calculator can make it for you.

What a calculator can do is stop presenting the two coverage figures as if they described the same job. They do not.

Published coverage against the film thickness it assumes
Product	Published sq ft/gal	Wet mils	Dry mils	1604 / wet mils	Volume solids	What the range means	Document
SuperPaint Exterior Latex Flat (A80)	350 to 400	4	1.5	401	38%	top end is the film, bottom is a 12% allowance	Sherwin-Williams document 102.01A, 9/2023
Duration Exterior Acrylic Flat (K32)	250 to 300	5.3 to 6.4	2.2	251 to 303	42%	both ends are film thickness	Sherwin-Williams document 102.06B, 3/2026
PrepRite Interior-Exterior Latex Block Filler (B25W00025)	75 to 125	16	7.7	100	48%	range straddles the theoretical film	Sherwin-Williams document 107.10, 11/2024

Read 2026-09-08. The fifth column is 1,604 divided by the wet mils in the third, and it is the theoretical coverage of a US gallon at that film thickness. Compare it with the second column.

Download this table as CSV. Same cells as printed above, nothing added.

Two exterior paints, a 60% difference, and no mystery in it

Duration Exterior Acrylic Flat (K32) publishes 250 to 300 sq ft per gallon. SuperPaint Exterior Latex Flat (A80) publishes 350 to 400. Sixty per cent apart, from one manufacturer, in one document format.

Both sheets print the wet film thickness beside the coverage, and that is where the difference is. A US gallon is 231 cubic inches, so at one mil thick it covers 1,604 sq ft, and any published coverage figure is that number divided by the film:

SuperPaint Exterior Latex Flat (A80): 4 mils wet. 1,604 ÷ 4 = 401.
Duration Exterior Acrylic Flat (K32): 5.3 to 6.4 mils wet. 1,604 ÷ 6.4 = 251, 1,604 ÷ 5.3 = 303.

So the second product is not thinner paint that stretches further. It is a thinner film, specified that way, and the sheet says so in the line directly beside the coverage figure. Outside, on a wall that has to survive weather rather than a hallway, that is the number worth reading.

The full derivation, and why the published range means something different on almost every sheet, is on the interior paint calculator.

The gable, and why it gets left out

Every other surface on a house can be measured with a tape and a ladder. The gable cannot, which is why estimates skip it and why the ones that do not usually guess it.

The arithmetic is simple: a gable is a triangle, so its area is half its base times its rise. The base is the gable-end wall, and the rise is from the top of the wall plate to the ridge. On the worked example that is half of 28 times 7, which is 98 sq ft per end.

The rise is the part to measure rather than assume, because it is set by the roof pitch and pitches vary enormously. A 4:12 roof on a 28 ft wall rises 4 ft 8 in and the gable is 65 sq ft. A 12:12 on the same wall rises 14 ft and the gable is 196, three times as much, on the same house.

A hip roof has no gable at all. Set the count to zero and the wall term has already covered it.

Bare block, and the one substrate the manufacturer prices in

Nothing on a data sheet tells you what texture does to coverage. Not lap siding, not rough sawn cedar, not stucco. The figures are for a film on a flat surface and the sheets do not pretend otherwise.

There is exactly one exception in this section, and it is worth seeing because of how large it is. For bare concrete block, Sherwin-Williams does not adjust the topcoat rate at all. It sends you to a different product: a block filler that goes on at 16 mils wet against a topcoat's 4, and publishes 75 to 125 sq ft per gallon. That is a quarter of the coverage, and it leaves 7.7 mils of dry film, five times a topcoat.

Which is the manufacturer telling you, in the only language a data sheet has, that bare block is not a painting problem. It is a filling problem, and the topcoat rate becomes meaningful again only once the holes are gone.

For everything between smooth siding and bare block, the honest answer is that nobody publishes a number. Paint one wall and measure what it took.

Spraying, and where the allowance goes

The 10% default on this page is for a brush and roller: the nap, the tray, the cut-in overlap and the inch in the can. It is our figure, not a manufacturer's, and it is a field because it should be arguable.

Spraying is a different quantity question. Overspray, wind and the paint left in the hose and the pump all come off the top, and the loss is far larger than a roller's. If you are spraying, raise the allowance and expect to be at the high end of whatever you raise it to on a windy day.

Back-rolling after spraying does not add paint. It moves what is already on the wall into the surface, which is what it is for.

Wet mils, dry mils, and why primer is not a finish coat

Every sheet prints two film thicknesses, wet and dry. Divide dry by wet and you have the volume solids: the share of what you rolled on that is still there once the water has gone. Everything else evaporated.

Product	Wet mils	Dry mils	Volume solids
SuperPaint Exterior Latex Flat (A80)	4	1.5	38%
Duration Exterior Acrylic Flat (K32)	5.3	2.2	42%
PrepRite Interior-Exterior Latex Block Filler (B25W00025)	16	7.7	48%

The PVA primer goes on at the same 4 mils wet as the topcoat and leaves 0.8 mils behind against the topcoat’s 1.4. That is why a primer coat does not count as one of your finish coats: it is doing a different job, sealing porous drywall paper so the topcoat sits on the surface instead of soaking in, and it leaves barely half the film.

It also explains the block filler. At 16 mils wet and 48% solids it leaves 7.7 dry mils, five times a topcoat, because it is not painting the block so much as filling the holes in it.

The sheets these figures were read from

Read 2026-09-08. Every figure on this page came from the manufacturer’s own product data sheet, quoted below as printed, with the document number and revision date the sheet carries.

Document	Revision	Coverage, as printed
SuperPaint Exterior Latex Flat, A80-Series	Sherwin-Williams document 102.01A, 9/2023	Coverage: 350-400 sq. ft. per gallon @ 4 mils wet, 1.5 mils dry
Duration Exterior Acrylic Flat, K32-Series	Sherwin-Williams document 102.06B, 3/2026	Coverage: 250-300 sq. ft. per gallon @ 5.3-6.4 mils wet, 2.2-2.7 mils dry, up to 7.0 mils wet: 3.0 mils dry
PrepRite Interior-Exterior Latex Block Filler, B25W00025	Sherwin-Williams document 107.10, 11/2024	Coverage: 75-125 sq. ft. per gallon @ 16.0 mils wet 7.7 mils dry

Why all six are Sherwin-Williams. Not a preference. Sherwin-Williams publishes its data sheets at a stable public address with a document number and a revision date on every one, which is what makes a figure citable. Where a brand’s coverage number could only be found on a retailer listing or a review site, it is not on this page, because repeating a number does not source it. If you are using another brand, read the back of your can and type the figure into the override field. The label beats this page.

Frequently asked questions

How much paint do I need to paint the exterior of a 2000 square foot house?: Floor area is the wrong input. A 40 by 28 ft two-storey house is about 2,240 sq ft of floor and about 2,572 sq ft of paintable surface once the four wall faces, two gables and the trim are counted and the doors and windows come out. At Duration's published 250 sq ft per gallon less a 10% allowance that is 11.4 gal a coat, so about 23 gallons for two coats.
How do I calculate the area of a gable?: Half the base times the rise. The base is the width of the gable-end wall and the rise is from the top of the wall plate to the ridge. A 28 ft wall with a 7 ft rise gives 98 sq ft. The rise depends entirely on the roof pitch, so measure it rather than assume it: a 12:12 gable is three times a 4:12 gable on the same house.
Why does one exterior paint cover 400 sq ft and another only 250?: Because they are specified at different film thicknesses, not because one is thinner paint. SuperPaint Exterior is 4 mils wet and Duration is 5.3 to 6.4. Divide 1,604 by each and you get the published figures exactly. Duration leaves 2.2 to 2.7 mils of dry film against SuperPaint's 1.5, so you are buying more coating and putting more on the wall.
Do I need to deduct windows and doors on an exterior estimate?: Yes, deduct the opening. Two doors and fourteen windows on the worked example is 208 sq ft, about 8% of the wall. Do not deduct the trim around them if you are painting it, because that goes into the trim quantity instead.
What do I use on bare concrete block?: A block filler before the topcoat, not more topcoat. Sherwin-Williams' PrepRite block filler goes on at 16 mils wet and publishes 75 to 125 sq ft per gallon, roughly a quarter of a topcoat's coverage, and leaves 7.7 mils of dry film. It is filling the holes in the block rather than colouring it.
How much extra should I allow for spraying?: More than the 10% default here, which is a brush and roller figure. No manufacturer publishes a spray allowance, so raise the field until it matches what you have actually seen. Overspray, wind and the paint left in the hose and pump all come off the top.
Does lap siding need more paint than flat siding?: It has more surface, because every course has an exposed butt edge that a flat measurement does not count, and the same is true of rough sawn cedar and stucco. No data sheet publishes a multiplier for any of it. If the texture is pronounced, paint one wall and measure what it took rather than trusting a factor somebody invented.

Check these numbers yourself

SuperPaint Exterior Latex Flat, A80-Series, document 102.01ASherwin-Williams, 9/2023. Coverage: 350-400 sq. ft. per gallon @ 4 mils wet, 1.5 mils dry
Duration Exterior Acrylic Flat, K32-Series, document 102.06BSherwin-Williams, 3/2026. Coverage: 250-300 sq. ft. per gallon @ 5.3-6.4 mils wet, 2.2-2.7 mils dry, up to 7.0 mils wet: 3.0 mils dry
PrepRite Interior-Exterior Latex Block Filler, B25W00025, document 107.10Sherwin-Williams, 11/2024. Coverage: 75-125 sq. ft. per gallon @ 16.0 mils wet 7.7 mils dry

How every figure here is verified: Sources & Method. Who builds this: About. Found something wrong? Tell us and it gets fixed or removed.

Figures on this page last checked against the source documents on 2026-09-08. Codes are amended locally; confirm against the edition your jurisdiction enforces.

Related calculators

The can beats this page. Coverage figures were read from the data sheets named above on 8 September 2026 and manufacturers revise them. The waste allowance is this calculator's default, not a manufacturer's figure. Wall faces are taken as flat: dormers, bays, porches and the butt edges of lap siding are extra, and no data sheet publishes a factor for surface texture.