GSM → GLM and fabric weight per roll

In a real company

Fabric merchandiser, fabric store, knitting / processing coordinator

Mills sell knitted fabric by the kilo, but the cutting room plans in metres. GLM (grams per running metre) is the bridge — it tells you how many metres you get from a kilo, and how much a roll should weigh.

Key ideas

• GLM = GSM × usable width in metres.
• 1 inch = 2.54 cm, so 72" = 1.829 m.
• kg per metre = GLM ÷ 1000; total kg = kg per metre × metres.
• Roll weight = width × length × GSM ÷ 1000 — use it to check a supplier's packing list.

Formula

GLM (g/m)

= GSM × Width (m)

Weight (kg)

= GLM × Length (m) ÷ 1000

Worked example

You need 1,000 m of a 180 GSM fabric, 72 inches wide. How many kilos should you book?

1. 1Width = 72 × 0.0254 = 1.829 m
2. 2GLM = 180 × 1.829 = 329.2 g per metre
3. 3Weight = 329.2 × 1,000 ÷ 1000 = 329.2 kg

✅ Book about 329 kg (plus your wastage allowance).

Common mistakes

• Using full width instead of usable (cuttable) width.
• Forgetting tubular knits are measured as a tube — open width is double.
• Mixing inches and centimetres.

Quick quiz

Answer 2 of 3 correctly to complete the lesson.

1. 1. GLM of a 200 GSM fabric that is 1.5 m wide?

   133 g/m300 g/m200 g/m3,000 g/m

2. 2. Why do merchandisers convert GSM to GLM?

   To find the colourMills sell by kg but cutting plans in metresTo calculate SMVFor freight CBM

3. 3. 72 inches is about…

   1.83 m0.72 m7.2 m1.52 m