Fabric · 4 min read
The three numbers that describe a fabric
What the spec sheet means
Fabric specifications are written for people who already know what they mean, which is why they so often read as a list of confident adjectives. Strip out the adjectives and there are three numbers and two words underneath.
The five things that carry information
- Weight (gsm)
- Grams per square metre. Under 140 is light and semi-opaque; 160–180 is standard game kit; over 200 is structured and warm.
- Knit
- Birdseye, micromesh, interlock, performance knit. Determines airflow and how evenly colour sits.
- Stretch
- Two-way or four-way. Four-way matters on anything close-fitting and is irrelevant on a loose cut.
- Composition
- 100% polyester, or a poly blend. Decides whether sublimation is even possible.
- Finish
- Wicking, anti-microbial, water-repellent. Real, but the smallest of the five effects.
What the adjectives are usually hiding
"Premium" and "professional grade" describe nothing. "Breathable" is a property of the knit — if a spec claims it without naming the knit, it is a claim rather than a specification. "Moisture-wicking" is genuine and is also true of essentially all performance polyester, so it does not distinguish one quote from another.
The number that gets left out most often is gsm, and it is the one that most affects how a garment feels in the hand. Asking for it is a reasonable request and a supplier who cannot answer it quickly is worth a second look.
Where a specification does matter enormously is the fit between fabric and sport, and the trade-offs are set out in our guide to choosing a fabric for a particular sport.
The five numbers on a spec sheet that mean something
A fabric specification is mostly noise around these.
- GSM
- Grams per square metre — the weight. It is the single most useful number, and the one that determines whether a garment survives contact or breathes on a warm court.
- Composition
- What it is made of, as percentages. Polyester takes sublimation; cotton does not. Elastane percentage tells you how much it gives.
- Knit type
- Interlock, mesh, jersey, birdseye. This decides airflow and how the colour reads, which is why the same dye reference looks different on two fabrics.
- Stretch direction
- Two-way stretches across the body; four-way stretches in both axes. For anything worn close to the skin on a body reaching overhead, four-way is the requirement rather than the upgrade.
- Finish
- Wicking, antimicrobial, UV. Real finishes are named and measurable; a finish described only as "premium" is a marketing word on a technical document.
What a spec sheet will not tell you
A specification describes the fabric as it leaves the mill. It says nothing about what fifty washes do to it, and that is the part a program actually experiences.
Two fabrics with identical GSM, composition and knit can behave completely differently after a season, because durability lives in the quality of the yarn and the tightness of the knit rather than in the numbers that get printed. This is the honest limit of reading a spec sheet: it lets you rule things out, not rule things in.
Which is why the useful move is to stop reading and start handling. Ask for the fabric in your hand, stretch it, hold it to the light, and if the supplier has an older garment in the same material, ask to see that instead — a two-year-old sample tells you more than any document. The full walk-through sits in our fabric guide.
Quick answers
Is heavier fabric better?
It is more durable and less comfortable. The right weight depends on the sport and the climate, not on a quality ranking.
Does a higher gsm mean better quality?
No. It means more cloth. A 220gsm volleyball jersey would be a bad volleyball jersey.
Which number should I look at first?
GSM. It is the weight, and it does more than any other figure to determine whether a garment survives contact or breathes on a warm indoor court. Everything else on the sheet is refinement around it.
Is a higher GSM always better?
No, and this is the most common misreading. Higher GSM is more durable and hotter. A volleyball shirt built to football weight is a bad volleyball shirt. The right weight is the one matched to the sport rather than the highest available.
Why does composition matter so much?
Because it decides what decoration is possible. Sublimation bonds to polyester and does not bond to cotton, so a cotton-rich fabric rules out the method before you have chosen a design. Elastane percentage tells you how much the garment gives.
What is the difference between two-way and four-way stretch?
Two-way stretches across the body only. Four-way stretches in both axes. For anything close-fitting worn by a body reaching overhead, four-way is the requirement rather than the upgrade, and it should be specified explicitly.
How do I judge a claimed finish?
By whether it has a name. Wicking, antimicrobial and UV finishes are real, specific and measurable. A finish described only as premium is a marketing word sitting on a technical document.
Does knit type actually affect anything I will notice?
Two things you will definitely notice: airflow, and how the colour reads. Mesh breathes more and reflects less light, so the same dye reference looks darker on it than on a smooth interlock.
What can a spec sheet not tell me?
What fifty washes do. Two fabrics with identical GSM, composition and knit can behave completely differently after a season, because durability lives in yarn quality and knit tightness rather than in the printed numbers.
So what should I ask for instead?
The fabric in your hand, and if the supplier has a two-year-old garment in the same material, that as well. A worn sample answers the durability question that no specification document can.