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Renovation & Construction

Exterior Paint Calculator

Estimate how many gallons or litres of exterior paint you need, accounting for rougher-surface coverage rates.

  • Answers as you type
  • Every formula cited
  • Calculated in your browser
SettingsSettings for this calculationUS
Market
Imperial · sales tax
The total siding/wall area to paint, not subtracting windows and doors unless they're large.

Measure each wall's height x width and add them together. Subtract large openings like garage doors; small windows and doors are usually left in as a buffer for trim work.

2 coats is standard for new siding or a color change; 1 coat may suffice for a refresh in the same color over sound existing paint.

Bare wood, masonry, or a major color change may need a primer coat in addition to the topcoats counted here.

Exterior paint needed

7.5 gallons

Medium confidence

Coverage varies by siding texture (stucco and rough-sawn wood need more paint than smooth vinyl or fiber cement) and paint brand — check your specific product's coverage rating.

Area to cover (all coats)
2,160 sq ft
Then change the inputs to see how far the answer moves.

Show calculation logic

How this was calculated

Formula source(s)

  • Exterior paint typically covers about 250-350 sq ft per gallon per coat, lower than interior drywall's ~350-400 sq ft due to siding texture and porosity

Inputs used

Exterior Wall Area
1080 sq ft
Number of Coats
2

Intermediate steps

Area to cover (all coats)
2,160 sq ft
Final result7.5 gallons

Confidence note: Coverage varies by siding texture (stucco and rough-sawn wood need more paint than smooth vinyl or fiber cement) and paint brand — check your specific product's coverage rating.

What this calculation does not cover

  • Coverage is fixed in the code at 300 square feet (28 m²) per gallon per coat, and there is no field for the spread rate printed on your tin, so at the 250 sq ft (23 m²) end of the range this page cites the same wall takes about a fifth more paint than the figure shown.
  • No opening is deducted inside the formula — the area you enter is multiplied straight through — and the guidance here is to leave small windows and doors in as a buffer for trim work, so a heavily glazed elevation reads high unless you subtract the large openings before typing the number.
  • Every coat is charged at the identical rate, because the arithmetic just multiplies area by the coat count: a thirsty first pass over bare, weathered or chalky siding is not distinguished from the finish coat sitting on top of it, and primer is not counted at all.
  • Only the paint that reaches the wall is counted, with nothing added for what stays in the tray, the roller or a sprayer's hose and overspray, and nothing held back as a touch-up reserve — the single cushion is the round-up to the next half gallon.
  • The 300 sq ft (28 m²) rate and that half-gallon step are both applied in US customary units before the answer is restated for the unit system you have selected, so a litre headline is a converted US gallon still carrying a half-US-gallon increment rather than a tin size, and 'gallons' here is always the US gallon the site converts at 3.785 L, never the larger imperial one.

Estimated cost — your price

This site holds no price list for this material — local prices vary too much to publish honestly. Enter your supplier's price and the result is costed with it.

32.86 ft10.02 m32.86 ft10.02 mequivalent area1,080 sq ft100.34 m²10 ft5 m

Part of bigger jobs

This trade is one line of several job takeoffs. Run the whole job and every other trade comes back with it, off the same measurements.

Computed in your browser — nothing you enter is uploaded. Presented in US customary units and US trade terminology. Where a formula follows a published standard, that standard and its edition are cited beside it on this page; where none governs, the page says so. Local amendments override model codes — verify against the code in force where you build.

Sources checked 2026-09-05 · in the site-wide review of 2026-09-06 · v1.0.1

Regulatory standards & verification citations1
  1. Exterior paint typically covers about 250-350 sq ft per gallon per coat, lower than interior drywall's ~350-400 sq ft due to siding texture and porosity
Cite this page

Your workspace

Most jobs need more than one number. Add the calculators you need next and they open right here, underneath this one — your figures stay on screen and nothing is lost to a page change.

Protection this work requires

  • Stop and check first. Paint under later coats in older housing can be lead-based, and sanding or heat-stripping it produces lead dust that is especially harmful to children and to anyone pregnant. Test before you disturb it — this is a job for a tested, controlled method, not a better mask.

Tools and safety for this job

To roll and cut in two coats and prepare a surface for paint. Generic types, no brands, no prices.

  • Joint-compound dust is very fine and travels: a P1/FFP1 mask is the minimum, and a damp-sponge finish avoids most of it.
  • A dust mask does nothing about solvent vapour: ventilate through, and use an organic-vapour (A1) cartridge respirator in an enclosed room.
  • Most fatal falls on small jobs are from under three metres: use a tower or a ladder tied at the top, and never work off the top two rungs.
Show the 11 tools this job needs

Essential

  • Brushes

  • Dust sheets and masking

  • Filling knife

  • Roller frame, sleeves and tray

  • Scraper

Recommended

  • Caulking gun

  • Extension pole

  • Pole sander

  • Random orbital sander

  • Step ladder

Optional

  • Dust extractor or vacuum with a fine filter

Also needed as materials: abrasive discs, caulk and sealant cartridges, masking tape, plastic sheeting, roller sleeves, sanding screens or paper.

what each painting tool is for, and the spec that decides which to buy where one does.

Now that you have the number

These guides cover the work this quantity is for.

Called something else where you work? Lead paint — the term in each market, how close the equivalence really is, and the standard that governs it.

Still deciding? Repaint vs Replace Siding — the factors that actually differ, with no invented prices.

Already have some? How much siding will my exterior paint cover?

Already gone wrong? The paint on my windows or exterior woodwork keeps failing

The data behind it: Production rates by operation

How to calculate exterior paint in 3 steps

  1. Exterior Wall AreaThe total siding/wall area to paint, not subtracting windows and doors unless they're large.
  2. Number of Coats2 coats is standard for new siding or a color change; 1 coat may suffice for a refresh in the same color over sound existing paint.
  3. Exterior paint neededThe tool computes the exterior paint needed from those figures and shows the formula, its sources, and a confidence rating alongside it.

Exterior paint needed by exterior wall area

Page defaults, not your figures above.

Exterior Wall AreaExterior paint needed (gallons)
500 sq ft3.5
1,000 sq ft7
1,500 sq ft10
2,000 sq ft13.5

Frequently asked questions

Why is exterior coverage lower than interior paint?
Exterior surfaces like stucco, brick, and wood siding are more textured and porous than smooth interior drywall, so more paint soaks in and covers less area per gallon.
Do I need a separate primer calculation?
For bare wood, masonry, or a drastic color change, yes — run this calculator again with 1 coat to estimate primer separately, since primer and topcoat are usually different products.
Does trim paint factor into this?
No — this is field/siding area only. Trim (fascia, soffits, window/door casings) typically uses a separate paint and a much smaller quantity, best estimated by its own linear footage.
Preliminary estimate, not certified engineering. This tool produces an indicative quantity calculation for planning purposes only — it is not a certified structural analysis, a guaranteed material takeoff, or a substitute for building department approval. Always verify measurements on-site and have a licensed contractor or structural engineer review any load-bearing, code-sensitive, or safety-critical work before purchasing materials or starting construction. Spotted an arithmetic or standards error? Report it to contact@craftquantities.com with your inputs — a confirmed fix gets a permanent check of its own, so the same mistake cannot come back.