To calculate the asphalt driveway cost, you just need to take a measurement of length x width to get the approximate square foot area, and multiply it by the average cost of $3-$4/square foot. Example: A driveway that’s 10′ wide and 60′ long equals 600 square feet.t that approximate cost, a driveway contractor will dig out 4-6 inches of whatever you already have in place, replace it with clean driveway gravel and grade it to a level and compacted surface. After that, they will put down 3-4 inches of base asphalt, and a final coating of 1-2 inches of topcoat.