This grip is 11 inches wide, and price is $0.50 PER INCH LENGTH. A Typical longboard is about 36 inches long. To find out how much you need, measure your deck carefully following its curved length. Dropped tub decks or camber/rocker will increase the length needed (do not just take a straight nose to tail measurement), maybe add 1 or 2 inches for extra clearance.

Comments by Gary: This is probably the best grip for anyone who is serious about longboarding. It is much coarser than regular skateboarding grip tapes, and it is double sealed with epoxy to last much longer. It is also perforated with small holes to prevent air bubbles on application. If this is still not coarse enough for you, check out the Gator Super XP at 24-grit.

note: pic shows gatorHD grip, hammer is the same but with the addition of anti-air bubble perforations.