Sealcoat Calculator

Sealcoat calculator

A sealcoat calculator divides the area of a driveway or lot by the coverage of the sealer. At 80 sq ft per gallon, a 30 × 12 ft driveway of 360 sq ft needs 4.5 gallons for one coat. At $15 a gallon, that is $67.50.

The number shown is not rounded, because gallons are poured and measured, but pails come in 5 gallons, so you buy in whole pails.

The formula in plain words

1. Area = length × width.
2. Gallons = area ÷ 80.
3. Cost = gallons × price per gallon.

For two coats, double the gallons. For a different coverage rate, replace 80 with the number on your pail.

Worked examples

The default driveway, 30 × 12 ft:

• Area: 360 sq ft
• Gallons: 360 ÷ 80 = 4.5
• Cost: 4.5 × $15 = $67.50
• Pails: one 5-gallon pail covers it

A two-coat job on the same driveway:

• Gallons: 4.5 × 2 = 9
• Pails: 2 pails (10 gallons)
• Cost at $15 a gallon: 9 × $15 = $135, though pails come in whole units

A small parking lot, 60 × 20 ft:

• Area: 1,200 sq ft
• Gallons: 1,200 ÷ 80 = 15
• Cost: 15 × $15 = $225, which is 3 pails

Gallons by driveway size

Driveway	Area	Gallons, one coat	Cost at $15
1-car, 12 × 20 ft	240 sq ft	3.0	$45.00
30 × 12 ft	360 sq ft	4.5	$67.50
2-car, 20 × 20 ft	400 sq ft	5.0	$75.00
50 × 12 ft	600 sq ft	7.5	$112.50
Wide, 24 × 24 ft	576 sq ft	7.2	$108.00

Rough surfaces use more sealer. If the asphalt is pitted, expect to use more than the table shows.

Prep matters more than the pail

• Clean the surface with a stiff broom and a blower. Remove oil spots with a degreaser made for asphalt.
• Fill cracks with a crack filler and patch holes. The cold patch calculator sizes bags for repairs.
• Let the surface dry fully.
• Check the label for weather limits. Many sealers need dry weather and air and pavement temperatures above about 50°F for the application and cure period.
• Block off the driveway for the cure time on the label.

Buying pails

Sealer is sold in 5-gallon pails and sometimes in larger drums. Divide the gallons by 5 and round up. The default 4.5 gallons is one pail, and 9 gallons for two coats is two pails. Since pails are priced as a unit, check the pail price against the per-gallon price you typed in, because they often differ.

How to measure

Measure length and width for a rectangle. For a driveway that widens at the street, treat the flare as a triangle: half the base times the height. Add the pieces together. Subtract grass islands or planters inside the area.

For a driveway with a curve, take the width in three places and average them.

Applying the sealer

• Stir the sealer well so the solids stay mixed.
• Cut in the edges with a brush.
• Pull the sealer across with a squeegee or spray it, working in a thin, even film.
• Work back toward the exit so you do not walk through the wet coat.
• Use the second coat only after the first has dried, as the label directs.

Common mistakes

• Applying one thick coat to save time. It tends to crack and peel.
• Sealing new asphalt too early.
• Buying exactly the calculated gallons. Cushion for edges and rough spots.
• Skipping cleaning. Sealer does not stick to dirt and oil.
• Sealing in cold or damp weather.

Related calculators

If the surface is beyond sealing, the asphalt calculator sizes a new layer, and the asphalt driveway cost calculator puts a price on it. For a bonding layer between new and old asphalt, the tack coat calculator finds the amount.