How it works
The calculator works out the area of the concrete, divides it by the sealer’s coverage for the first coat and for each further coat, and rounds the total up to whole containers.
Area = Length × Width
Sealer = (Area ÷ First-coat coverage + Area × (Coats − 1) ÷ Later-coat coverage) × (1 + Extra ÷ 100)
Containers = ⌈ Sealer ÷ Container size ⌉
⌈ ⌉ means rounding up to the next whole number. For most products the first-coat and later-coat coverage are the same figure, so the formula is simply Area × Coats ÷ Coverage. In “known area” mode the area you enter replaces length × width.
The worked example
A 24 × 12 ft patio has 288 sq ft. Foundation Armor’s AR350 data sheet lists 175–225 sq ft per gallon in one coat on old or porous concrete, so at the low end two coats take 288 × 2 ÷ 175 = 3.29 gallons – four one-gallon containers. On dense, trowel-finished concrete the sheet gives 250–325 sq ft per gallon, and the same patio needs 576 ÷ 250 = 2.30 gallons, or three containers.
Porous or dense concrete
How far a sealer goes depends more on the concrete than on the sealer. Broom-finished, exposed-aggregate, old and weathered concrete is open and absorbent; a steel-troweled garage floor is dense and smooth. Where a data sheet gives both figures, a “Concrete surface” choice appears and starts on porous, the more conservative choice. QUIKRETE gives 150–200 sq ft per gallon for its Acrylic Concrete Cure & Seal used as a sealer, depending on the texture, and notes that coverage depends on the porosity of the surface.
First and later coats
The first coat fills the pores; the second mostly stays on the surface. Behr states this in its data sheet for Wet-Look Sealer No. 985: the first coat at 200 sq ft per gallon and the second at 450. The calculator applies those two rates when you pick that product. For the other products the data sheets give one figure, and it is used for every coat, which leans towards more sealer.
Units and containers
Measurements, coverage and container size are converted to one internal unit before calculating, so you can enter the patio in feet and inches and buy in gallons or quarts. One US gallon is 231 cubic inches (NIST Handbook 44). In metric, coverage is in m² per liter; container sizes vary by brand and market, so none is filled in – enter the size you’ll buy to see the number of containers.
Worked example
Inputs
- Measure by
- Length × width
- Length
- 24 ft
- Width
- 12 ft
- Number of coats
- 2
- Sealer
- Foundation Armor AR350 – 175 sq ft/gal porous, 250 dense (≈ 4.3 / 6.1 m²/L)
- Concrete surface
- Porous, rough or old (broom finish, exposed aggregate, weathered)
- Extra sealer
- 0 %
- Container size
- 1 gal
Result
- Area to seal
- 288 sq ft
- Coverage used (first coat)
- 175 sq ft/gal
- Sealer needed
- 3.29 gal (13.17 qt)
- Containers
- 4
Common mistakes
- Using a dense-surface coverage figure on broom-finished, exposed-aggregate or old, weathered concrete. Porous concrete drinks sealer – choose the porous figure if in doubt.
- Putting on one thick coat instead of two thin ones. Foundation Armor says to avoid excessive build-up and puddles, and QUIKRETE says not to apply more than the recommended amount.
- Assuming the second coat takes as much as the first. Where the data sheet gives a separate second-coat rate, the second coat goes further because the pores are already filled.
- Using one sealer’s coverage for a different type. Penetrating, film-forming, wet-look and cure-and-seal products differ widely in coverage.
- Forgetting steps, curbs and the sides of a raised patio. Measure them as extra rectangles and add them to the area.
Assumptions and limits
- The area is a rectangle of length × width, or the area you enter. Joints, cracks and texture are not added.
- Coverage is the documented rate of the product you pick – the low end of its range – or the figure you type. For Behr Wet-Look Sealer the first coat uses 200 and later coats 450 sq ft per gallon, as its data sheet states; other products use one figure for every coat.
- For products with separate figures, the porous or rough figure is used unless you choose dense.
- Containers are rounded up to whole containers of the size you choose; the calculator does not mix sizes.
- Surface preparation (cleaning, etching, stripping old sealer) is not included.
Frequently asked questions
How much area does a gallon of concrete sealer cover?
It depends on the product and how porous the concrete is. Foundation Armor lists 175–225 sq ft per gallon in one coat on old or porous concrete and 250–325 on dense, trowel-finished concrete for AR350. QUIKRETE gives 150–200 sq ft per gallon for Acrylic Concrete Cure & Seal used as a sealer, depending on the texture of the surface. Behr gives 200 sq ft per gallon for the first coat of its Wet-Look Sealer and 450 for the second. The calculator uses the low end of each range.
How many coats of concrete sealer do I need?
Follow the label. Foundation Armor says AR350 is designed to be applied in two thin coats, not one thick coat, and Behr’s data sheet gives film thicknesses for a first and a second coat.
Why does porous concrete need more sealer?
Open, rough or weathered concrete absorbs sealer into its pores before a film forms. That is why Foundation Armor gives 175–225 sq ft per gallon on porous surfaces but 250–325 on dense, trowel-finished ones.
Can I use this for pavers or stamped concrete?
Yes, if the sealer is made for them. Measure the paved area and pick the porous figure or type the coverage your sealer gives for pavers.
Is this the same as a driveway sealer for asphalt?
No. Asphalt (blacktop) driveways use a different product sold by the pail; use the driveway sealer calculator for those.
Sources
- BEHR PREMIUM Wet-Look Sealer No. 985 – Technical Data Sheet (rev. 11/2015) — Behr Process Corporation. "1st Coat … @ 200 Sq. Ft./Gal. 2nd Coat … @ 450 Sq. Ft./Gal." and "Coverage: 200-450 Sq. Ft./Gal. depending on application method and substrate porosity" (preset: 200 for the first coat, 450 for later coats).
- Armor AR350 Wet Look/Satin Gloss Acrylic Sealer – Technical Data Sheet — Foundation Armor. "Old or Porous Surfaces 175-225 ft2/gallon in one coat; Dense or Trowel Finished Surfaces 250-325 ft2/gallon in one coat" (preset: 175 porous, 250 dense).
- Acrylic Concrete Cure & Seal No. 8730 – Data Sheet — The QUIKRETE Companies. Sealer applications: "Apply at a uniform thickness to obtain a coverage of 150 – 200 ft2/gal (3.7 - 4.9 m2/L), depending on the texture of the surface" (preset: 150 rough, 200 smooth); sizes 1 gal (3.8 L) bottle and 5 gal (19 L) pails.
- NIST Handbook 44, Appendix C – General Tables of Units of Measurement — National Institute of Standards and Technology. Exact unit definitions: 1 in = 2.54 cm, 1 yd³ = 27 ft³, 1 US gal = 231 in³, 1 lb = 0.45359237 kg.
Method reviewed November 5, 2026