Sealer cans promise a coverage number, and the real world rarely matches it. Bare concrete drinks, film-forming products go on thicker than you think, and the second coat always stretches further than the first. Here is how to land on the right number of gallons without a second trip to the store.
The short answer
Plan on about 250 square feet per gallon per coat for a typical mid-range sealer, and plan on two coats. A 20 × 20 ft driveway (400 sq ft) therefore needs roughly 3 gallons; a 12 × 20 ft one-car garage floor (240 sq ft) needs about 2. The concrete sealer calculator does this math and rounds up to whole gallons for you.
Coverage per gallon by sealer type
The product type moves the answer more than anything else. Thin penetrating sealers soak in and spread far; thick decorative and epoxy coatings sit on top and cover far less.
| Sealer type | Per gallon, one coat | Typical use |
|---|---|---|
| Penetrating (silane / siloxane / silicate) | 200–400 sq ft | Driveways, walkways, freeze-thaw protection |
| Acrylic, water- or solvent-based | 150–300 sq ft | Patios, wet-look and color-enhancing finishes |
| Polyurethane | 200–300 sq ft | High-traffic floors, stamped concrete topcoat |
| Epoxy floor coating | 150–250 sq ft | Garage and shop floors |
| Paver sealer (on pavers) | 100–200 sq ft | Paver patios, joint stabilizing |
Those are first-coat numbers on typical broom-finished concrete. Smooth, troweled, or previously sealed concrete lands at the high end; rough, old, or very porous slabs at the low end.
How to calculate it, step by step
- Measure the area. Length × width in feet gives square feet. Break an L-shaped driveway into two rectangles and add them.
- Multiply by the number of coats. Two is standard for almost every sealer.
- Divide by the coverage per gallon printed on your can, or use 250 if you have not picked a product yet.
- Round up to whole gallons, and add about 5% if the slab is rough or you are spraying on a breezy day.
Worked example: a 24 × 24 ft two-car driveway is 576 sq ft. Two coats is 1,152 sq ft of coverage; divided by 250 that is 4.6 gallons, so buy 5. Switch to a penetrating sealer rated at 350 sq ft per gallon and the same driveway needs 3.3 gallons, so a single 5-gallon pail with room to spare.
What 1 gallon and 5 gallons actually cover
One gallon covers about 250 sq ft in one coat, which is a 10 × 12 ft patio with two coats, or a single coat on a one-car garage floor. It is the right size for steps, a small stoop, or a walkway.
Five gallons covers about 1,250 sq ft in one coat, or roughly 600 sq ft with two coats. That is a 20 × 30 ft driveway, a two-car garage plus a walkway, or a large patio. With a penetrating sealer the pail stretches toward 1,750–2,000 sq ft per coat; with a heavy epoxy it may only manage 750–1,000. Five-gallon pails usually cost 15–25% less per gallon than singles, so once you need more than three gallons the pail is the better buy.
Why the first coat drinks more
New and bare concrete is full of open pores, so the first coat disappears into the slab and covers 20–30% less than the label. The second coat sits on a partly sealed surface and goes noticeably further. If you are re-sealing a slab that was sealed a few years ago, expect coverage closer to the top of the range on both coats.
Concrete sealer vs driveway sealer
If your driveway is asphalt (blacktop), you need sealcoat, not concrete sealer. Sealcoat is a thick emulsion that covers only about 80–100 sq ft per gallon, so a 400 sq ft asphalt driveway needs a 5-gallon pail per coat. The driveway sealer calculator uses the right coverage for asphalt.
Pavers and stamped concrete
Pavers have sand joints and porous faces, so they cut coverage roughly in half compared with a slab; budget 100–200 sq ft per gallon. Stamped concrete has more surface area than its footprint and usually gets a film-forming acrylic or polyurethane, so use the low end of that product's range.
Sprayer or roller: does it change the amount?
A pump sprayer lays down a thinner, more even coat and typically gets you the label coverage or a bit better with penetrating and solvent sealers. A roller puts on more material per pass, so thick acrylics and water-based sealers rolled on land toward the low end of the range. Either way, keep a wet edge and do not let sealer puddle; puddles cloud and peel, and they waste product.
How much to buy
Round up to the next whole gallon, then add one extra if the slab is rough, old, or unsealed. Leftover sealer keeps for a year or more in a closed can and is exactly what you want for touch-ups. Plug your dimensions into the concrete sealer calculator and adjust the coats to match your product's label.