Asphalt Sealer / Driveway Sealer Calculator
Enter your driveway dimensions, number of coats, and sealer type to calculate how many buckets of sealcoat you need and what the materials will cost.
Estimate only — not professional advice. Always verify results independently before purchasing materials or beginning work. Terms of Use
What is Asphalt Sealer / Driveway Sealer?
An asphalt sealer calculator determines the number of gallons and buckets of driveway sealcoat needed based on driveway area, number of coats, and the type of sealer being applied. Sealcoating protects asphalt driveways and parking lots from UV degradation, water penetration, oil and gasoline spills, and oxidation that causes the surface to become brittle and crack over time. The calculation is straightforward: driveway area multiplied by the number of coats gives the total coverage area. Dividing by the sealer's coverage rate per gallon determines total gallons needed, which is then divided by 5 to convert to standard 5-gallon bucket count. Two main types of driveway sealer are available for residential use. Coal tar sealer (also called coal tar emulsion or refined tar sealer) is the traditional commercial-grade product used by professional sealcoating contractors. It offers superior resistance to gasoline, oil, and UV damage, with a coverage rate of approximately 80 square feet per gallon when applied at proper thickness. Coal tar sealer produces a deep black finish and lasts 3 to 5 years between applications. Asphalt emulsion sealer is a petroleum-based alternative that is less toxic, lower odor, and more environmentally friendly than coal tar. It covers approximately 60 square feet per gallon because it is typically applied at greater thickness. Asphalt emulsion is becoming the standard in many regions where coal tar has been banned or restricted due to environmental concerns (coal tar contains polycyclic aromatic hydrocarbons, or PAHs, which are harmful to waterways). Asphalt emulsion lasts 2 to 3 years between applications. Professional sealcoating contractors always apply two coats. The first coat penetrates into the asphalt surface, filling small pores and creating a bond. The second coat builds the protective surface layer that resists wear and weathering. Single-coat applications are significantly less durable and are not recommended by any sealer manufacturer. For heavily worn or porous driveways, a third coat may be warranted. Application conditions matter significantly. Sealer should be applied when the air temperature is above 50 degrees F and rising, with no rain forecast for 24 to 48 hours. The driveway must be completely clean, with all oil stains treated with a primer, and all cracks wider than 1/4 inch filled with rubberized crack filler. Sealer applied over dirty or oil-stained asphalt will not bond and will peel within months. Driveway sealer is sold in 5-gallon buckets at home improvement stores (typically $25-45 per bucket) and in 55-gallon drums for contractors. The 5-gallon bucket is the standard unit for residential projects. Always buy in complete buckets — partial buckets cannot be stored once opened because the sealer skins over and becomes unusable.
How to Calculate
- Measure the driveway length and width in feet
- Set the number of coats (2 is the industry minimum)
- Select the sealer type based on your preference and local availability
- Enter the cost per 5-gallon bucket from your local supplier
- Review the area, gallons, bucket count, and estimated material cost
- Add crack filler, primer, and applicator costs separately (not included)
Formula
Area = Driveway Length (ft) x Driveway Width (ft) Total Coverage Area = Area x Number of Coats Gallons Needed = ceiling(Total Coverage Area / Coverage per Gallon) Buckets Needed = ceiling(Gallons Needed / 5) Total Cost = Buckets Needed x Cost per Bucket Coverage rates: Coal Tar = 80 sq ft/gal, Asphalt Emulsion = 60 sq ft/gal. These rates assume a properly cleaned and prepared surface with medium porosity.
Example Calculation
A 40 ft x 12 ft driveway, 2 coats of coal tar sealer (80 sq ft/gal), at $35 per 5-gallon bucket: Area = 40 x 12 = 480 sq ft Total Coverage Area = 480 x 2 = 960 sq ft Gallons = ceil(960 / 80) = 12 gallons Buckets = ceil(12 / 5) = 3 buckets Total Cost = 3 x $35 = $105.00
Frequently Asked Questions
How often should I sealcoat my driveway?
Sealcoat every 2 to 3 years for optimal protection. New asphalt should cure for at least 6 to 12 months before the first sealcoat application. Over-sealing (annually) can actually cause problems — thick buildup becomes brittle and flakes. The sealer should be visibly worn and the asphalt color showing through before reapplication.
Is coal tar or asphalt emulsion sealer better?
Coal tar offers superior chemical and UV resistance, lasting 3 to 5 years versus 2 to 3 years for asphalt emulsion. However, coal tar contains PAHs (polycyclic aromatic hydrocarbons) that are harmful to waterways, and it has been banned in some states and municipalities. Asphalt emulsion is more environmentally friendly, lower odor, and easier to apply. For most homeowners, asphalt emulsion is the practical choice unless maximum durability is the priority.
Can I apply sealer myself or should I hire a contractor?
Driveway sealing is one of the most accessible DIY exterior maintenance tasks. A homeowner with a squeegee applicator or roller can seal a standard two-car driveway in 2 to 4 hours. The key is thorough cleaning (pressure wash, degrease oil stains, fill cracks) and applying two thin coats rather than one thick coat. Professional contractors charge $0.15 to $0.25 per square foot, so a 480 sq ft driveway costs $70 to $120 for labor alone.
How long does driveway sealer take to dry?
Most sealers are dry to foot traffic in 4 to 8 hours and ready for vehicle traffic in 24 to 48 hours. Apply the first coat in the morning and the second coat in the late afternoon once the first is dry to touch. Cooler temperatures, high humidity, and shade extend drying time significantly. Do not drive on the sealed surface until it is fully cured — early traffic will leave tire marks and scuffs.
Do I need to fill cracks before sealing?
Yes. Cracks wider than 1/4 inch must be filled with rubberized crack filler and allowed to cure (24-48 hours) before sealing. Sealer is a surface coating — it cannot bridge or fill cracks. Unfilled cracks allow water to penetrate beneath the sealer, causing the asphalt to deteriorate from below and the sealer to peel away from the crack edges. Crack filling is the most important preparation step.
Why does my sealer peel or flake off?
The most common causes are: applying over dirty or oil-stained asphalt (sealer cannot bond), applying too thick (one heavy coat instead of two thin coats), applying when temperature is too low (below 50 degrees F), applying before rain (sealer washes off before curing), and applying over an existing buildup of old sealer that was not properly adhered. Proper cleaning and thin coats solve most adhesion problems.