Driveway sealer renews the dark color of an asphalt driveway, smooths the surface and covers tiny cracks or old patches. You can spread it with a brush or spray it on. It usually comes in 1-gallon or 5-gallon containers and the amount you need depends on the size of your driveway, as well as the texture of the surface. For instance, a rough surface needs as much as 65 percent more sealer than smooth driveway with the same square footage, according to CSGNetwork's driveway sealer calculator.
Measure the length of your straight driveway a tape measure or measuring wheel. Round the measurement to the nearest foot.
Measure the width of your straight driveway. Round the measurement to the nearest foot.
Multiply the length of your straight driveway times its width to determine the square footage.
Divide the result by 80 for an average driveway. The result is the estimated number of gallons of driveway sealer you'll need.