Roll Coverage Calculator

How the number is worked out

Overlap comes off the sides and the ends, so a roll covers less ground than it measures. Strips of width w lapped by o cover w + (n − 1)(w − o), which sets the passes across the site and the rolls along each.

The widest roll is not always the cheapest. A 27 ft width takes two 15 ft passes and wastes 2.5 ft, or one 15 and one 12.5 and wastes nothing, so the calculator tries every combination and buys the one that wastes least.

Cutting decides how far a roll goes. Anything cuts across to any length, so the part roll each pass ends on is shared: a 328 ft roll finishes fourteen passes that each need 22 ft. Fabric also splits down the middle into two half-width strips, which covers a narrow last pass for half a roll. Geogrid keeps its width.

Rolls do not come cut. Cut them on site, or tell us what you need and we will cut them before they ship. You buy the whole roll either way, and everything rounds up. A roll short mid-job costs more than a spare on the trailer.

Overlap applies to the dimensions only. A quantity off a plan set already carries the engineer's own allowance, so that figure is divided by the roll and left alone.

Paving fabrics are not here. We install those rather than selling them by the roll. See asphalt interlayers.