Calculate cloth requirements, weights, and costs for sailmaking
"My Boat Plans" is a collection of over 500 boat plans, from simple dinghies to larger cruisers. It includes step-by-step guides, video tutorials, and more.
Download NowOrdering sailcloth is the moment a design becomes a bill of materials, and getting the yardage wrong means either a half-finished sail or an expensive pile of offcuts. A sail is cut from panels laid out along the cloth's width, so the amount you buy depends on the sail's area, how the panels nest on the roll and the layout waste that every cut pattern generates.
Weight and cost follow directly from the cloth's ounce rating and the area you lay out, because sailcloth is sold by weight per square yard and price per linear yard at a given width. Heavier Dacron lasts on a cruising genoa, light laminate suits a racing shape, and the choice drives both the load on the sewing machine and the bill.
Enter luff and foot, choose the sail type and the cloth weight and width, and the calculator estimates panel layout, total yardage including waste, cloth weight and cost so you can order with confidence.
Sail Area = (Luff × Foot) ÷ 2; Yardage = Area ÷ Layout Factor ÷ Cloth Width; Weight = Area × Cloth Ounces ÷ (width factor)| Sail Type | Layout Factor | Common Cloth | Note |
|---|---|---|---|
| Mainsail | 0.85 | 6 - 9 oz Dacron | Durable cruising weight |
| Jib / staysail | 0.88 - 0.90 | 6 - 8 oz | Efficient triangular cut |
| Genoa | 0.82 | 7 - 10 oz | Large, heavier for load |
| Spinnaker | 0.75 | 0.7 - 1.5 oz nylon | Light, high waste |
Layout efficiency and typical cloth by sail type.
Formula verified against standard naval-architecture references · Updated October 2026
Start with the sail's area from luff and foot, divide by a layout factor that accounts for the waste when panels are cut and nested, then divide by the roll width to reach linear yardage. A triangular cut wastes less than a big genoa, and spinnakers waste most. The calculator applies a per-sail-type factor and the cloth width so the yardage covers the real cut, not just the bare area.
By sail type and how hard it works. Cruising mains and genoas commonly use 6 to 10 ounce Dacron for durability and shape under load, lighter 5 to 7 ounce suits small or reaching sails, and specialist light-air sails use very thin nylon or laminate. Heavier cloth lasts and holds its shape but adds weight and cost, so match the weight to the sail's role rather than defaulting to the heaviest.
Because sail panels are cut on the cloth's straight and bias grain and must fit within the roll's width, so the shape of the sail never tiles perfectly onto a rectangle. Curved leeches and overlapping panels leave offcuts too small to reuse, and bigger or rounder sails waste more. The layout factor captures that loss so your order actually covers the pattern.
Dacron woven cloth is the cruising default: strong, durable, forgiving on the seams and stable for years of UV and rough handling. Laminate and radial constructions hold shape better and are lighter for racers and serious cruisers, but cost more and are less tolerant of furling abuse and sun. Choose Dacron for longevity and easy handling, laminate when shape and weight justify the price.
Multiply the cloth's ounces per square yard by the sail's area to get fabric mass, then add thread, tape, corners, bolt rope and hardware. Cloth dominates the number, so weight tracks area and cloth choice, which is why a big genoa in heavy Dacron can weigh far more than a light-air sail of similar size and why the calculator reports it.
It changes the yardage and the seams. Wider cloth means fewer linear yards and fewer seams for the same area, which can save labour and weight, but not all cloths come in all widths and the cut must still fit. Price per yard differs by width and material, so cost is a function of area, layout efficiency, width and cloth type together.
Close enough to order sensibly once you add a small surplus, but the true figure comes from laying out the actual pattern. Cut plans, seam allowances and panel style all shift the amount used, so use the calculator for a solid estimate and contingency, and confirm against the loft's cutting layout before committing to an expensive cloth order.