Boat Shrink Wrap Size Calculator
Measure the finished support frame profile and enter the cover drop and allowances. The calculator matches those dimensions to a standard marine roll and shows how much of that roll each cover uses.
Recommended standard roll17 ft × 120 ft
- Minimum film width
- 15
- Required cut length
- 28
- Complete boat cuts per roll
- 4
- Film area per boat
- 476
- Roll-length utilization
- 93.33%
- Unused roll length
- 8
- Perimeter strap length
- 56
Film area uses the selected roll width, not the calculated minimum width.
Perimeter strapping excludes knot, splice, seam, and tie-down allowances.
How to use this calculator
- Measure the boat length and transom width in feet after accounting for the finished cover shape.
- Measure from one rub rail, over the completed ridge or highest point, then add the intended drop below the rail.
- Choose tuck and end allowances that suit the way you will gather and seal the film.
- Review the selected roll, complete cuts per roll, unused length, and perimeter strap estimate before ordering.
How to size a boat shrink-wrap roll
Measure the actual cover path, not just the boat's published beam. Start at one rub rail, follow the path over the completed support ridge or the highest point, and finish at the opposite rub rail. Add the planned drop below the rub rail and enough film at each side to tuck and fuse. This is especially important when a windshield, flybridge, pulpit, radar arch, or tall frame changes the profile.
This calculator uses the one-side measurement and doubles it:
minimum film width = 2 × (rub rail to ridge + drop below rub rail + side allowance)
It also adds material at both ends of the boat:
required cut length = boat length + 2 × end allowance
The result compares those dimensions with a fixed list of standard marine rolls: 12 × 175, 14 × 150, 17 × 120, 20 × 100, 24 × 115, 26 × 100, 32 × 100, 40 × 100, and 50 × 100 feet. It selects the narrowest roll that is wide enough and long enough for one complete cut. The number of complete covers is the roll length divided by the cut length, rounded down.
Yield, waste, and strapping
Film area per boat uses the selected roll width rather than the calculated minimum width: selected roll width × required cut length. This is the amount of film that must be unrolled for one cover, including the difference between the calculated need and the next available roll width. Roll-length utilization is the length used by all complete cuts divided by the full roll length. The unused length is the remainder that cannot make another full cover.
For a first strapping estimate, the calculator uses 2 × boat length + transom width. It is the perimeter around the sides and stern before allowance for knots, splices, seams, or a specific strapping pattern. A broad transom, swim platform, or unusual stern geometry can require more material.
What moves the result most
The ridge measurement has the largest effect on roll width, because it is doubled. Measure after the support frame is complete and include every protrusion that must fit under the film. Boat length and end allowance control cut length and therefore how many covers a roll can yield. A small increase in cut length can reduce the whole-number yield when it crosses the remaining length on a roll.
What this calculator leaves out
This is a material-dimension estimate, not an installation plan. It does not choose film thickness, support-frame strength, band spacing, vents, access doors, reinforcement patches, seams, damaged film, or practice material. Confirm the exact roll dimensions and stock with the supplier, and follow the film and heat-tool instructions; heat work can damage a boat and create fire and burn hazards.
Worked example
For a 24 ft boat with an 8 ft transom, suppose the one-side rub-rail-to-ridge path is 4 ft, the film drops 2 ft below the rail, the tuck allowance is 1.5 ft per side, and the end allowance is 2 ft per end. The minimum width is 2 × (4 + 2 + 1.5) = 15 ft and the cut length is 24 + 2 × 2 = 28 ft.
The 17 × 120 ft roll is the narrowest listed roll that fits. It produces floor(120 ÷ 28) = 4 complete cuts, uses 112 ft of the roll, and leaves 8 ft. Each cover uses 17 × 28 = 476 square feet of film, and the roll-length utilization is 112 ÷ 120 = 93.33%. The perimeter strap estimate is 2 × 24 + 8 = 56 ft. At a $400 roll price, allocated film cost is $400 ÷ 4 = $100 per boat.
Common questions
How do I measure a boat for shrink wrap?
Measure the cover path from one rub rail over the completed support ridge or highest point to the opposite rub rail, then add the planned drop and tuck allowance on both sides. Measure length along the finished cover from bow to stern and add material at both ends. Include every fitting and frame member that must sit under the film.
Should I measure before or after building the support frame?
Measure after the support frame is complete whenever possible. A ridge pole, arch, windshield, pulpit, or flybridge can increase the cross-section enough to change the required roll width. The finished frame is the shape the film must cover.
How much extra shrink wrap should I leave on each side?
A practical starting allowance is about one to two feet per side for tucking and fusing, adjusted for the hull shape and your installation method. The allowance belongs in addition to the measured cover path and drop below the rub rail. Use more where the cover needs to gather around irregular geometry.
What size roll fits a pontoon or flybridge boat?
Measure the actual support-frame profile rather than choosing from boat length alone. Pontoons can need extra width around rails and furniture, while a flybridge or tall arch can make the ridge path much larger than the beam suggests. If the calculated width exceeds the listed roll widths, obtain a supplier recommendation for a wider roll or a seamed cover plan.
How many boats can one shrink-wrap roll cover?
Divide the selected roll length by the required cut length and round down to a whole number. The remainder may still be useful for patches or smaller jobs, but it cannot make another complete cover of the same size. A different boat size or a larger end allowance changes the yield.
How much perimeter strapping do I need?
The calculator starts with twice the boat length plus the transom width. Add material for knots, splices, banding layout, tie-downs, and any geometry that makes the actual path longer. Follow the film supplier's strapping instructions for the support and wind conditions.