Gsm — grams per square meter — is the first number on any fabric spec, and the most misread. Heavier is not “better quality”; weight is a design decision about opacity, structure, warmth and drape.

Typical ranges and what they feel like

Performance legging fabrics commonly run around 200–280 gsm: the lighter end feels cooler and more mobile, the heavier end more sculpting and warmer. Bra and top fabrics often sit lighter, roughly 160–220 gsm, with linings and powernet adding structure where needed. Summer training tees can drop to 120–160 gsm.

These are orientation ranges, not rules — knit structure moves the feel dramatically. A dense 220 can wear warmer than a loose 250. Always judge the actual fabric, on a body, in motion.

Weight vs opacity — the misunderstanding

Buyers often chase gsm to fix see-through samples. Opacity under stretch depends on knit density, yarn count, cross-section and dye depth as much as raw weight; adding 30 gsm of loose knit fixes nothing and adds warmth the studio customer resents.

The correct sequence: define the opacity requirement first (backlit squat test in the palest colorway), then let the mill hit it with the lightest construction that passes.

Seasonality and line planning

Running one legging weight year-round is common and defensible, but seasonal capsule logic — a lighter summer knit, a brushed heavier winter version of the same block — gives customers a reason to buy twice and search engines two products to rank.

Keep the block and change the fabric: fit stays approved, sampling is faster, and the collection reads coherent.

How to specify weight sensibly

Spec gsm with a tolerance (commonly ±5%) and pair it with the measurements that actually protect you: stretch percentages, recovery after wash, and the opacity pass condition. At final inspection, fabric weight is verified against the approved spec — at SEAMDANCE that check is part of AQL 2.5 inspection against the sealed reference.

When comparing supplier quotes, compare at equal gsm and composition; a cheaper quote at 20 gsm lighter is a different product, not a better price.

Quick answers

What gsm should premium yoga leggings be?

Most premium studio leggings cluster around 230–270 gsm in nylon/spandex, but the honest answer is: the lightest fabric that passes your opacity and recovery requirements with the hand feel your customer expects.

Does higher gsm mean more compression?

No. Compression comes from fabric modulus and pattern reduction. Weight adds warmth and opacity potential, not hold.