Concrete sealer coverage calculator
Work out how many gallons of concrete sealer you need for a given area, coverage rate and number of coats, and what the material will cost.
Calculator
400 sq ft at 200 sq ft/gal over 2 coats needs about 4.0 gal (buy 4). Coverage varies by product — confirm on the can.
Concrete sealer is sold by coverage rate — the square feet one gallon covers in a single coat — which varies a lot by product and by how porous or textured the surface is. A thin, penetrating siloxane sealer might stretch to 250 sq ft per gallon, while a film-forming acrylic on a rough or exposed-aggregate surface may only reach 150. Most jobs also call for two coats. This calculator turns your area, the coverage rate from the label, and the number of coats into the gallons you need and what they will cost at your price.
The result shows the exact gallons required and the whole gallons to buy (you cannot buy a fraction of a can), plus the material cost. Because coverage is the one number that changes between products, it is an input, not a hidden constant — always confirm it against the can before you order.
Formula
Gallons scale with area and coats and divide by the coverage rate:
gallons = area_sqft ÷ coverage_sqft_per_gal × coats
cost = gallons × price_per_gal
- coverage_sqft_per_gal — from the product label; typically 150–250.
- coats — most sealers need two thin coats for even protection.
- The tool also rounds gallons up to whole cans for purchasing.
Worked example
To seal a 400 sq ft patio with a sealer rated 200 sq ft/gal, applying 2 coats, at $35/gal:
gallons = 400 ÷ 200 × 2 = 4 gal
cost = 4 × $35 = $140
So you need 4 gallons and about $140 of sealer. On a rough surface rated only 150 sq ft/gal, the same two coats would need about 5.3 gallons — six cans to buy — which is why the coverage rate matters so much.
Coverage rates and real-world overage
Coverage rates on the can assume a properly prepared, clean, dry surface; a porous, weathered or freshly acid-etched slab drinks more sealer, so round up and keep a little extra on hand. The first coat on bare concrete always uses the most. Sealer pairs naturally with decorative finishes — size a coat for stamped, colored or exposed-aggregate concrete, or after a resurfacing job. These are labeled planning quantities — confirm the coverage rate on your product.
Frequently asked questions
How much does a gallon of concrete sealer cover?
Typically 150–250 square feet per gallon per coat, depending on the sealer type and how porous or textured the surface is. Penetrating sealers cover more; film-forming acrylics on rough surfaces cover less. Use the figure printed on your product.
How many coats of sealer does concrete need?
Most concrete sealers are applied in two thin coats for even, durable coverage. Always follow the label; some penetrating sealers specify a single saturating coat instead.
How do I calculate how much sealer to buy?
Divide the area by the coverage rate and multiply by the number of coats, then round up to whole gallons. For 400 sq ft at 200 sq ft/gal over two coats that is 4 gallons. This calculator does the rounding for you.
Should I buy extra sealer?
Yes — a porous or weathered slab absorbs more than the rated coverage, and the first coat on bare concrete is the thirstiest. Buying one extra can avoids stopping mid-job.