Backpacking Fabric Chart: Denier, Weight, Durability

Almost every argument about gear fabric goes wrong in the same place: someone compares a denier number to a different material's denier number. Denier is the mass in grams of 9,000 metres of a single yarn. It describes how thick a thread is. It does not describe how strong a fabric is, how waterproof it is, or how long it will last, and it cannot be compared across materials at all.

What exactly is denier and what does it not tell you?

Take a single yarn, measure out 9,000 metres of it, and weigh it in grams. That weight is the denier. A 20D yarn means 9,000 metres weighs 20 grams. A 210D yarn means the same length weighs 210 grams, so it is roughly ten times thicker in cross section. That is the entire definition.

Inside a single material and weave, denier is a useful ranking. Take two silnylon flies from the same maker, one 20D and one 30D, and the 30D will be heavier, thicker, more abrasion resistant and less likely to be punctured by a stick under the floor. That comparison is fair because everything except yarn thickness is held constant.

Across materials it tells you nothing. Dyneema fibre is dramatically stronger per unit weight than nylon, and Dyneema Composite Fabric is not woven at all: it is a grid of unidirectional fibres laminated between polyester films. A 0.51 oz per square yard sheet of it has no meaningful denier and outperforms woven nylon many times heavier on tear strength. Ultra laminates use a similar approach on the pack side. So "is 20D or 30D better" is a real question and "is 20D nylon or 1.0 oz Dyneema better" is not a denier question at all.

The number that does compare across materials is tear strength, usually published in pounds or newtons from a trapezoidal or tongue tear test, alongside fabric weight. If a maker publishes tear strength, use it. If they publish only denier, you can compare their fabrics to each other and to nothing else.

How much does each backpacking fabric weigh?

Fabric weight is quoted either in ounces per square yard or grams per square metre. One ounce per square yard is about 33.9 grams per square metre. The table below gives published typical figures for the fabrics that appear on shelter and pack spec sheets. Nearly everything is a range, because coating weight, ripstop grid, calendering and finish all shift the figure between suppliers, and a single decimal would be false precision.

Read that table by group rather than as one ranked list. The shelter fabrics sit between roughly 0.5 and 2.2 oz per square yard. The pack fabrics sit between roughly 2.6 and 13. The two groups barely overlap, and comparing a fly fabric to a pack fabric is comparing a raincoat to a tyre.

Silnylon, silpoly, Dyneema or polyester: which coating and material?

Once you have the weight, the material choice is a set of trade-offs, and the same four candidates come up on every shelter spec sheet. Here is what actually separates them.

What does a hydrostatic head rating actually mean?

Hydrostatic head is measured by clamping the fabric under a vertical tube of water and recording the height of water column, in millimetres, at which water is forced through. A 1,200 mm rating means the fabric held back a 1,200 mm column. It is a lab number and it is not a rainfall figure, but it does rank fabrics sensibly.

The practical readings are these. Around 1,000 to 1,500 mm is the common floor for a shelter fly and copes with ordinary rain falling on a taut surface. Around 3,000 mm is the level at which a fabric keeps working under pressure, and pressure is the thing people forget. Kneeling on a wet tent floor concentrates your body weight through a small area and generates far more force than rain ever does, which is exactly why floors carry higher ratings than flies, often 3,000 to 10,000 mm on the same tent.

A rating is also not permanent. Silicone impregnation is stable but abrasion thins it, and polyurethane coatings hydrolyse with age, heat and storage while damp, which is how a tent that was waterproof five years ago starts misting through in steady rain. Store shelters dry and loose, not compressed in a stuff sack in a hot garage.

Why does silnylon sag and does it matter?

Nylon is hygroscopic: the fibre takes up water into its structure, swells, and the yarn lengthens. A silnylon fly pitched drum tight at dusk can be visibly slack by midnight in rain, and a slack fly touches the inner, sheds badly and flaps in wind. The standard answer is a mid-night trip outside to re-tension the guylines, which is why experienced silnylon users pitch with adjustable line-locs on every guy point rather than fixed knots.

Polyester does not absorb water in the same way, so silpoly holds its pitch through a wet night. Dyneema Composite Fabric has essentially no stretch in any condition, wet or dry, which is a large part of why cottage shelter makers moved to it. That is the real reason for the shift toward silpoly and Dyneema across the last decade, more than the weight saving. A Durston X-Mid 2 Pro in Dyneema is pitched once and stays pitched, while the NEMO Hornet OSMO 2P uses a polyester based fabric for the same reason on the freestanding side.

Does it matter? On a dry weekend, no. On a five day trip with rain on three of the nights it is the difference between sleeping and getting out of a warm quilt at 1am in the rain. Weigh that against the cost difference honestly rather than treating sag as a specification footnote.

How do these fabrics behave on a pack rather than a shelter?

Packs live in a different world. A fly is loaded evenly and rarely abraded. A pack is dragged against granite, jammed under bus seats, sat on, and loaded with sharp edged gear from the inside. Abrasion resistance, not tear strength, is what usually kills a pack fabric.

That is why 210D robic nylon remains the value answer: at 3.5 to 4.5 oz per square yard it is light enough for a two pound pack and tough enough to last years. X-Pac and EPLX laminates add a waterproof film and a stiffer hand that helps a frameless pack hold its shape, at a few extra ounces. Ultra laminates and Dyneema Composite Fabric take the weight down again and are effectively waterproof, which is how a Hyperlite Mountain Gear Southwest 55 lands at 2 lb 0 oz and a Zpacks Arc Haul Ultra 60 at 1 lb 5 oz. Those fabrics can wear through at hip belt and shoulder strap contact points before a woven nylon would, which is the cost of the weight saving.

None of these fabrics makes a pack waterproof at the seam and zip level, which is why a pack liner is standard regardless of fabric. The pack roundup covers which fabric suits which base weight, and the Big Three guide explains why the pack is the last of the three to buy.

How does fabric choice change packed volume?

Weight and bulk are not the same problem, and Dyneema Composite Fabric is the clearest example. It is dramatically lighter than silnylon for the same shelter, and it packs bigger. The reason is structural: a laminate creases rather than compresses, so a Dyneema fly folds into a stiff slab where a silnylon fly of the same area stuffs into whatever gap is left in the pack.

That matters more than it sounds when you are choosing pack volume. Two hikers with identical base weights can need different pack sizes purely because one carries a laminate shelter and a synthetic quilt while the other carries silnylon and high fill down. Down compresses further than anything else in the pack, silnylon compresses well, coated polyester less so, and laminates barely at all.

Pack fabrics run the same way. X-Pac and Ultra laminates have a stiff hand that helps a frameless pack hold its shape and resist barrelling, which is a genuine structural benefit, but it also means the empty pack does not fold flat. A 210D robic pack packs down into itself. A laminate pack does not, which matters if you ever need to stow it.

How do you repair and maintain each fabric?

Repairability should be part of the buying decision, because light fabrics get damaged and the question is only whether you can keep using them afterwards. Each material has a different answer, and carrying the wrong repair kit for your fabric is the same as carrying none.

Silnylon and silpoly do not accept ordinary adhesive tape reliably, because silicone impregnation is designed to shed things. They take silicone based repair patches and silicone sealant, and both sew well, so a needle and thread plus sealant over the stitching is a permanent field repair. Seams on these fabrics cannot be factory taped either, which is why many silnylon shelters ship unsealed and expect the owner to run a bead of thinned silicone along the seams before the first trip. Skipping that step is a common reason a new shelter leaks.

Dyneema Composite Fabric is the opposite. Dyneema tape bonds to it extremely well and a tape patch on both sides is effectively a permanent repair, which is why cottage makers often ship a roll of it with the shelter. It does not sew well, because stitching perforates a laminate whose strength comes from continuous fibres and films, and it delaminates at the end of its life rather than tearing. Polyurethane coated polyester takes standard tape and patches and sews fine.

Maintenance is mostly about storage. Store every shelter dry, loose and out of heat. Compressed, damp storage is what hydrolyses polyurethane coatings and what turns a functioning fly into one that mists through in steady rain. Wash pack fabrics with plain water rather than detergent, since surfactant residue in a coated fabric is a leak path.

How do I use this chart when choosing gear?

Work in this order. First decide the job: shelter fly, shelter floor, pack body, quilt shell. Second, pick a weight band from the table that suits how hard you will use it. Third, only then compare denier, and only inside the same material.

A concrete example. Two 20D silnylon flies from different makers are directly comparable, so pick on price, geometry and seam sealing. A 20D silnylon fly against a 1.0 oz Dyneema fly is not a denier comparison at all: it is a comparison of weight, sag, UV life, noise, packed bulk and cost, and the answer depends on how many nights a year you will use it. The tent weight chart puts real published shelter weights next to each other, and the trekking pole versus freestanding comparison covers the structural side of the same decision.

One more principle worth stating plainly: fabric choice does not change what conditions a shelter can survive. A tarp in 1.0 oz Dyneema is still a tarp. A single wall shelter in an expensive laminate is still a single wall shelter. Going ultralight must not mean going unprepared, and shelter adequate to the conditions you will actually meet is a fixed cost, not a place to save grams. Choose the shelter type for the trip first, then choose the fabric that shelter is built from. The tent roundup starts from that order.