Concrete Sealer Calculator

1. Enter the length and width of the area you want to seal.
2. Enter the coverage per coat from your sealer label, in square feet per gallon.
3. Set the number of coats and a waste allowance.
4. Read the result: the gallons you need, rounded up to whole gallons and to five-gallon pails.

Here is what each result line means:

A concrete sealer calculator tells you how much sealer to buy for a driveway, patio, garage floor or other slab. It turns the area, the coverage rate on the label and the number of coats into gallons, with a little extra for waste.

It works for both acrylic film-forming sealers, which usually take two coats, and penetrating sealers, which often take one. Because coverage depends so much on the product and the surface, the calculator uses the coverage rate you enter from the label rather than assuming one. To size the slab itself first, use the concrete slab calculator.

The math is straightforward. The area divided by the coverage rate gives the gallons for one coat. Multiply by the number of coats, then add the waste allowance, and round up to whole gallons.

1. Multiply length by width to get the area in square feet.
2. Divide the area by the coverage rate to get the gallons for one coat.
3. Multiply by the number of coats.
4. Add the waste allowance, then round up to whole gallons.

Coverage is the figure that moves the result most. A smooth, sealed surface takes the high end of a product range, while a rough, broom-finished or porous surface drinks more and takes the low end.

Suppose you are sealing a 20 by 24 foot driveway, 480 square feet, with an acrylic sealer rated at 250 square feet per gallon, in 2 coats, with a 10 percent waste allowance.

Calculation: one coat is 480 divided by 250, which is 1.92 gallons. Two coats make 3.84 gallons. Adding 10 percent brings it to about 4.22 gallons. Rounded up, you would buy 5 gallons, which is one five-gallon pail.

The lesson: the coverage rate and the number of coats drive the quantity, so read the label before you buy.

Coverage Rate

This has the biggest effect. Acrylic sealers are commonly 200 to 400 square feet per gallon, and penetrating sealers are often lower. The label figure is the one to trust.

Surface Porosity and Texture

A smooth, dense or previously sealed surface takes less; a rough, broom-finished or porous surface takes more and may need an extra coat. Use the low end of the coverage range for rough concrete.

Number of Coats

Acrylic sealers usually take two thin coats. Many penetrating sealers take one, or two on very porous concrete. Two thin coats beat one thick coat for an even finish.

Waste and Overlap

Some sealer is lost to overlap, soak-in and spillage. Around 10 percent covers it; add more for a very rough or irregular surface.

The two main types seal in different ways and use different amounts, so the comparison matters before you buy.

Acrylic sits on top and changes the look; penetrating soaks in and leaves the surface unchanged. Always take the coverage and coats from the specific product label, since ranges vary widely between brands.

Buying the Right Amount

Avoid a second trip to the store, or a pail of leftover sealer, by buying close to what the job needs.

Comparing Products

See how a 200 and a 400 square feet per gallon sealer differ in cost once you account for the area and the coats.

Planning a Reseal

Work out the sealer for a driveway or patio you reseal every few years, so the budget is ready.

1. Assuming One Coverage Rate

Coverage ranges widely by product and surface. Use the label figure, not a generic number, and lean to the low end for rough concrete.

2. Forgetting the Second Coat

Most acrylic sealers need two coats. Buying for one leaves you short halfway through.

3. Applying It Too Thick

A thick acrylic coat can bubble, blush or peel. Two thin coats give a better, more durable finish than one heavy one.

4. Ignoring the Surface Prep

Sealer bonds to a clean, dry, cured surface. Dirt, moisture or an old coating changes both the result and the coverage.

5. Skipping the Test Patch

A small test area confirms the look and the real coverage before you commit the whole slab.

The arithmetic is exact, but the real coverage depends on your product and surface, so treat the result as a planning estimate and follow the label.

Divide the area by the coverage rate on the label, multiply by the number of coats, and add about 10 percent for waste. A 480 square foot driveway at 250 square feet per gallon in two coats needs about 4.2 gallons, so you would buy five.

It depends on the product and the surface. Acrylic sealers are commonly 200 to 400 square feet per gallon per coat, and penetrating sealers are often lower. A rough or porous surface uses more, so always check the label.

Acrylic film-forming sealers usually take two thin coats. Many penetrating sealers take one coat, or two on very porous concrete. Two thin coats give a more even, durable finish than one thick coat.

Acrylic sealer forms a film on the surface and adds a sheen or wet look. Penetrating sealer soaks in and protects against water and salt without changing the appearance. They cover different amounts, so use the label figure for each.

Yes. Around 10 percent covers overlap, soak-in and spillage. Add more for a very rough, broom-finished or irregular surface, which drinks more sealer than a smooth one.

Yes. Enter the area, the coverage rate and the coats for any flat concrete, such as a garage floor, patio, sidewalk or pool deck. The method is the same.

Coverage depends on the sealer type, the solids content and how porous the surface is. A dense, smooth slab takes far less than a rough, open one, which is why manufacturers give a range and recommend a test area.

The math is exact for the numbers you enter. The uncertainty is in the real coverage, which varies with the product and surface, so treat the result as a planning estimate and follow the label.

No. The calculation runs entirely in your browser and nothing you enter is stored or sent anywhere.

• Quikrete Concrete and Masonry Gloss Sealer (acrylic sealer, 200-400 sq ft per gallon, coverage varies with porosity).
• SealMaster Concrete Sealer (acrylic sealer, 200-300 sq ft per gallon, optional second coat).
• Sika Sikagard H-1001 silane penetrating sealer (penetrating silane sealer data sheet; porous substrates may need a second coat).