Quick answer
Sealer needed (gallons) = area × coats ÷ coverage per gallon. A 50 × 20 ft driveway (1,000 ft²) with 2 coats at 80 ft² per gallon needs 25 gallons.
Enter length, width, coverage per gallon and the number of coats. The calculator returns gallons and area. Use this asphalt sealer calculator to check your own figures.
Related tools: Asphalt Tonnage Calculator: Tons of hot-mix asphalt for a paved area. Roof Pitch Calculator: Roof pitch as rise per 12 inches, angle, slope percent and rafter length factor. Tile Calculator: Number of tiles (and boxes) for an area.
How to use the Asphalt Sealer Calculator
- Enter length (ft) (above 0).
- Enter width (ft) (above 0).
- Enter coverage per gallon (ft²) (above 0).
- Enter coats (a whole number, between 1 and 5). It starts at 2.
- Press Calculate to see the result, and use Reset to start again.
| Input | What to enter | Allowed values |
|---|---|---|
| Length | A number, in ft | > 0 |
| Width | A number, in ft | > 0 |
| Coverage per gallon | A number, in ft². Printed on the container | > 0 |
| Coats | A whole number | ≥ 1, ≤ 5, starts at 2 |
Formula and method
Formula
gallons = length × width × coats ÷ coverage
IEEE-754 double precision; shown to the decimals indicated.
Use the coverage rate printed on the sealer container. Plan geometry only; confirm quantities with your supplier and local code before ordering.
Worked examples
These examples are verified: each one is an automated test case that the live calculator must reproduce exactly.
Example 1
Inputs: Length = 50; Width = 20; Coverage per gallon = 80; Coats = 2.
| Result | Value |
|---|---|
| Sealer needed | 25 gal |
| Area | 1,000 ft² |
Example 2
Inputs: Length = 30; Width = 12; Coverage per gallon = 70; Coats = 1.
| Result | Value |
|---|---|
| Sealer needed | 5.1 gal |
| Area | 360 ft² |
The first line is the headline result (sealer needed). Below it the asphalt Sealer Calculator lists area, which describe the same case from other angles. IEEE-754 double precision; shown to the decimals indicated.
Coverage varies
Labels often state 70 to 100 ft² per gallon per coat for smooth asphalt. Rough or cracked surfaces soak up more, so use the lower end. Two thin coats outperform one thick coat.
Prepare first
Clean, repair cracks and apply when the temperature is suitable. Order a little extra for edges and waste. Sealing is usually repeated every two to three years.
How the result changes with length
Holding every other input at the first worked example, this table changes only length. It shows how sensitive the answer is to that one value; each row was produced by running this calculator.
| Length | Sealer needed | Area |
|---|---|---|
| 25 | 12.5 gal | 500 ft² |
| 50 | 25 gal | 1,000 ft² |
| 100 | 50 gal | 2,000 ft² |
| 200 | 100 gal | 4,000 ft² |
What happens with invalid input
These messages are produced by the calculator itself, so you know what to fix.
- Length: entering "0" shows "Length must be greater than 0." beside that field and no result.
- Coverage per gallon: entering "0" shows "Coverage per gallon must be greater than 0." beside that field and no result.
Choosing between the Asphalt Sealer Calculator and similar calculators
Each row shows what a related calculator on this site asks for and what it returns, so you can pick the one that matches your question.
| Calculator | You enter | It returns |
|---|---|---|
| [Asphalt Tonnage Calculator](/construction/asphalt-tonnage-calculator/) | length, width and compacted thickness | Asphalt needed |
| [Roof Pitch Calculator](/construction/roof-pitch-calculator/) | i know the and value | Pitch |
| [Tile Calculator](/construction/tile-calculator/) | area to tile, tile length and tile width | Tiles needed |
| [Aquarium Volume Calculator](/construction/aquarium-volume/) | length, width and water height | Capacity |
| [Flooring Calculator](/construction/flooring-calculator/) | room length, room width and waste allowance | Flooring to buy |
Background: construction estimates
Material quantities are geometry plus a margin. Calculate the exact volume or area, add an allowance for waste, spillage, cuts and uneven ground (calculator pages commonly mention 5 to 10 percent, a rule of thumb that varies by material and job) and round up to whole units. One cubic yard is exactly 27 cubic feet.
Suppliers often have minimum order sizes and may charge for small loads, so confirm quantities, product yields and local code with your supplier or a qualified estimator before ordering.
Assumptions and limitations
- Rough surfaces use more sealer
Quantities are estimates. Add allowances for waste and site conditions, and follow local codes and a qualified professional's instructions for structural or safety-critical work.
If a required value is empty, not a number, or outside its allowed range, the form marks that field with a message and shows no result instead of a misleading number. The automated checks deliberately try invalid entries for length and coverage per gallon to confirm this.
Frequently asked questions
How long should sealer cure?
Usually 24 to 48 hours before traffic.
How many coats?
Two thin coats are common for driveways.
Does it include crack filler?
No. It estimates sealer only, not crack filler.
What does the Asphalt Sealer Calculator calculate?
Gallons of driveway sealer for an area. It returns Sealer needed and Area.
What formula does the Asphalt Sealer Calculator use?
gallons = length × width × coats ÷ coverage. Use the coverage rate printed on the sealer container.
What do I need to enter in the asphalt Sealer Calculator?
You enter Length (ft), Width (ft), Coverage per gallon (ft²) and Coats.
How is the result rounded or limited?
IEEE-754 double precision; shown to the decimals indicated. Rough surfaces use more sealer.
What is an example of a asphalt Sealer result?
With length 50, width 20, coverage per gallon 80 and coats 2, the sealer needed is 25 gal.
Can I rely on this calculator for a decision?
Quantities are estimates. Add allowances for waste and site conditions, and follow local codes and a qualified professional's instructions for structural or safety-critical work. For this calculator in particular: Rough surfaces use more sealer.
Related calculators
- Asphalt Tonnage Calculator — Tons of hot-mix asphalt for a paved area.
- Roof Pitch Calculator — Roof pitch as rise per 12 inches, angle, slope percent and rafter length factor.
- Tile Calculator — Number of tiles (and boxes) for an area.
- Aquarium Volume Calculator — Capacity and filled weight of a rectangular aquarium.
- Flooring Calculator — Flooring area with waste, and boxes if you know the coverage per box.
- Roof Shingles Calculator — Squares and bundles of shingles for a roof area.
- Drywall Calculator — Sheets of drywall for walls after deducting openings.
- Plywood Calculator — Sheets of plywood or OSB for an area.
- Wallpaper Calculator — Rolls of wallpaper from room perimeter, height and pattern repeat.
Sources
- OpenStax, Prealgebra 2e (Rice University): perimeter, area, volume, circumference and the Pythagorean theorem
- NIST Special Publication 811, Guide for the Use of the International System of Units (SI), Appendix B conversion factors (international foot 0.3048 m, inch 25.4 mm, US gallon 3.785411784 L)
Content last reviewed 2026-11-04. Formulas and worked examples are checked by automated tests against independently computed values.