GSM Calculator

The Single Number That Defines a Fabric's Weight Class

GSM — grams per square meter — is the standard way the textile industry expresses how heavy or light a fabric is, independent of roll size. A lightweight voile might sit around 100 GSM while a heavy denim or upholstery fabric can run past 400 GSM. This calculator handles the two things done with GSM most often: measuring it directly from a small sample, and converting between GSM and the oz/yd² unit still common in North American sourcing.

The Formulas

GSM = Sample Weight(g) ÷ Sample Area(m²)
oz/yd² = GSM ÷ 33.906
GSM = oz/yd² × 33.906

33.906 is the standard conversion factor between grams per square meter and ounces per square yard, derived from the fixed relationship between grams-to-ounces and meters-to-yards.

Where This Matters

Testing an unlabeled fabric — cutting a small sample of known area and weighing it gives an accurate GSM reading without needing a specification sheet.
Sourcing across regions — US mills commonly quote oz/yd² while most of the rest of the world uses GSM, so cross-checking a supplier's numbers requires converting between the two.
Matching a fabric to its intended use — GSM ranges correspond roughly to end use, from lightweight linings to heavy canvas, making it a quick first filter when evaluating a fabric.

Typical GSM Ranges by Fabric Weight Class

General GSM weight classes used in the textile trade
Weight class	Typical GSM range	Example use
Lightweight	Up to 150 GSM	Voile, chiffon, lightweight shirting
Mid-weight	150–300 GSM	T-shirt jersey, standard shirting, chinos
Heavyweight	300–500 GSM	Denim, canvas, sweatshirt fleece
Extra heavy	Above 500 GSM	Upholstery, heavy canvas, outerwear

These weight-class ranges are general industry reference points rather than strict boundaries; exact classification varies by fiber type and finish.

Worked Example

GSM from sample: 2.5 g over a 100 cm² sample = 250 GSM
Convert: 250 GSM ÷ 33.906 = 7.3733 oz/yd²

How to Use This Calculator

Choose a mode: Calculate GSM from Sample or Convert GSM / oz/yd².
For Calculate GSM from Sample: enter Sample Weight in grams and Sample Area in square centimeters.
For Convert: enter a Value and choose the conversion direction.
Select Calculate to get the result for the chosen mode.

Related Calculations

Apply a known GSM to a full roll with the Fabric Weight Calculator, or check filament yarn fineness with the Denier Calculator.