Greige-to-Finished Shrinkage & GSM Yield Calculator
Convert loom-state greige width, GSM, and batch metres into finished cuttable width, finished GSM, GLM, and linear metres per kg after scouring, dyeing, and heat-setting.
Why dyeing shrinkage increases GSM while chemical scouring reduces mass
When loom-state polyester greige enters open-width scouring, disperse dyeing, peaching, and stenter heat-setting, three things happen simultaneously: weft width contracts by 5%–10%, warp length contracts by 2%–5%, and desizing/scouring/peaching removes 2%–12% of fibre and size mass. Because total area shrinks faster than mass is lost, finished GSM almost always rises above greige GSM.
Finished GSM = Greige GSM × (1 − Weight Loss) ÷ [(1 − Width Shrinkage) × (1 − Length Shrinkage)]
280 cm / 88 GSM peachskin greige (−7% width, −3% length, −3% mass loss) → 260.4 cm cuttable width · 94.6 GSM finished · 246.4 g/m GLM
Usual 160–330. Limit 50–360.
Usual 55–280. Limit 20–500.
Usual 1000–50000. Limit 10–500000.
Usual 4–12. Limit 0–35.
Usual 1–6. Limit -10–35.
Usual 1.5–15. Limit 0–40.
Finished cuttable width
260.4 cm · 102.5 in
Finished areal weight (GSM)
94.6 GSM (+7.5%)
Finished yield length
4,850 m · 5,304 yd
Finished linear weight (GLM)
246.4 g/m
Finished yield per kg
4.06 m/kg · 4.44 yd/kg
Batch mass (greige → finished)
1232 kg → 1195 kg
Selectable Greige-to-Finished Mass-Balance Formulas
Every dyeing order balances fibre mass across area contraction. Copy these formulas directly into your mill costing sheet:
Finished Width (cm) = Greige Width (cm) × (1 − Width Shrinkage % ÷ 100)
Finished Length (m) = Greige Length (m) × (1 − Length Shrinkage % ÷ 100)
Finished GSM = Greige GSM × (1 − Mass Loss % ÷ 100) ÷ [(1 − Width Shrinkage % ÷ 100) × (1 − Length Shrinkage % ÷ 100)]
Finished GLM (g/m) = Finished GSM × (Finished Width cm ÷ 100) | Metres per kg = 1,000 ÷ Finished GLM
Worked example (280 cm, 88 GSM waterjet greige for disperse-printed bedding): Notice that when warp length shrinkage (3%) equals desizing/peaching mass loss (3%), the two factors cancel out in the GSM numerator and denominator! Finished GSM is simply 88 ÷ (1 − 0.07) = 94.62 GSM, finished width is 280 × 0.93 = 260.4 cm (trimmed to 260 cm cuttable), and linear density stays 246.4 g/m (4.06 m/kg).
Standard Mill Finishing Shrinkage & GSM Shift Reference Table
Typical greige-to-finished transformations across Changxing waterjet polyester programs.
| Finishing route & program | Greige spec (width / GSM) | Shrinkage (W / L / Mass loss) | Finished spec (width / GSM) | Finished GLM & m/kg |
|---|---|---|---|---|
| Disperse-printed bedding peachskin | 280 cm / 88 GSM | −7% / −3% / −3% | 260 cm / 94.6 GSM | 246 g/m (4.06 m/kg) |
| Piece-dyed washed microfiber sheet | 300 cm / 98 GSM | −6.5% / −4% / −2.5% | 281 cm / 106.5 GSM | 299 g/m (3.35 m/kg) |
| Bleached white hotel satin stripe | 300 cm / 118 GSM | −6% / −3% / −2% | 282 cm / 126.8 GSM | 358 g/m (2.80 m/kg) |
| Alkali-reduced (jianliang) faux-linen / sheer | 160 cm / 72 GSM | −8% / −4% / −12% | 147 cm / 71.7 GSM | 106 g/m (9.47 m/kg) |
| 3-pass piece-dyed curtain blackout | 300 cm / 225 GSM | −6.5% / −2.5% / −2% | 281 cm / 241.9 GSM | 678 g/m (1.47 m/kg) |
| 300D brushed & backed sofa upholstery | 160 cm / 165 GSM | −6% / −3% / −2.5% | 150 cm / 176.4 GSM | 265 g/m (3.77 m/kg) |
Common questions
- Why does GLM stay constant when warp shrinkage equals chemical weight loss?
- Linear density (GLM, grams per metre) depends only on mass per unit length. Weft-way width shrinkage narrows the cloth without changing how many grams sit in one linear metre. When a 3% warp contraction concentrates mass per metre by 1/(1−0.03) and a 3% scouring weight loss removes (1−0.03) of mass, the two cancel out and finished GLM equals greige GLM.
- What weight loss percentage should I enter for alkali reduction (caustic weight reduction)?
- Standard desizing and scouring on polyester filament greige removes 1.5%–3.0% (mostly water-dispersible size and spinning oil), whereas mechanical peaching adds another 1%–1.5% flock loss. True caustic alkali reduction (jianliang) on high-twist or cationic-drape fabrics dissolves 8%–18% of the polyester surface polymer to create a silk-like drape.
- How much extra greige length should a converter book for a 10,000 m finished order?
- Divide your target finished length by (1 − Warp Shrinkage) and add 1.5%–2.0% for end-of-roll seams, leader cloth, and lab inspection cuts. For a 3% warp shrinkage route, booking 10,500 m of greige reliably yields 10,000 m of export-packed finished rolls.