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GSM Calculator
Fabric GSM from weight and sample area. Verify supplier quality.
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Fabric Weight Calculator — Roll Weight & Lot Weight
Calculate the total weight (grams, kg, tonnes) of a fabric roll or full production lot from GSM, fabric width and roll length. Add price per kg to estimate total fabric cost. Essential for fabric buying orders, inventory checks and cost reconciliation. No account needed — numbers update as you type.
Weight calculation assumes uniform GSM across full roll length and width. Actual roll weight varies ±3–5% due to moisture content, roll tension and GSM variation within the roll. Weigh rolls on arrival and compare with invoice to catch systematic short-weighting.
Step By Step
How to Use This Calculator
5 steps
- Enter the fabric GSM — get this from the supplier's test certificate or measure it yourself using the GSM Calculator.
- Enter the fabric width in centimetres, using the usable width (exclude selvedge — deduct 1–2 cm per edge).
- Enter the roll length in metres (from the roll ticket or measured with a fabric measuring machine).
- Enter the number of rolls in the lot — the calculator shows both per-roll weight and total lot weight.
- Optionally enter the fabric price per kg to get an estimated total cost for the lot.
Worked Example
Worked example — 10 rolls of 160 GSM jersey
Use this sample to sanity-check your inputs and understand what the final result represents.
- 1GSM: 160 · Width: 150 cm (1.50 m) · Roll length: 100 m
- 2Weight per roll: 160 × 1.50 × 100 ÷ 1,000 = 24.0 kg
- 310 rolls: 24.0 × 10 = 240 kg total
- 4Fabric price: $3.80/kg → Total cost: $912.00
Final Result
10 rolls = 240 kg · Estimated fabric cost at $3.80/kg = $912.00.
Methodology
Fabric Weight Formula — derived from GSM definition
This section explains the calculation logic, assumptions, and source material used to make the result more trustworthy and easier to verify.
Weight per roll (kg) = GSM × Width (m) × Length (m) ÷ 1,000. Total lot weight = Weight per roll × Number of rolls. Fabric cost = Total weight (kg) × Price per kg. This formula is a direct algebraic rearrangement of the GSM definition: GSM = mass (g) ÷ area (m²), therefore mass (g) = GSM × area (m²) and mass (kg) = GSM × area ÷ 1,000. Standard test for verifying GSM: ISO 3801:1977 / ASTM D3776. Roll weight verification: place roll on calibrated floor scale on arrival; deviation of more than ±3% from invoice weight warrants investigation.
Practical Guidance
Fabric weight and buying — what purchasing teams check
- 1Knit fabric is traded by weight in Bangladesh and most Asian markets — always confirm whether the price is per kg or per metre and convert if needed using the price conversion formula: price/kg = price/m ÷ (GSM × width m ÷ 1,000)
- 2Woven fabric is typically sold by metre — verify GSM from a test sample before accepting delivery; woven fabric GSM is harder to manipulate but thread count changes are used to reduce cost while staying within the visible specification
- 3Short-weighting (delivering rolls lighter than invoiced) is a known problem in bulk fabric supply; weigh a 10% sample of rolls on arrival and compare to the supplier's roll ticket — consistent 1–3% shortfalls across rolls indicate deliberate under-weighting, not random variation
- 4Roll length verification: unroll and measure or use a fabric measuring machine with yardage counter; short lengths affect your cutting yield and can cause production shortfalls
- 5Moisture adds significantly to fabric weight at high humidity — cotton fabric at 80% RH can weigh 3–5% more than at 65% RH standard; always store and test in climate-controlled conditions where possible
- 6Keep a fabric receipt register: PO number, supplier, roll count, invoiced weight, actual weighed weight, price per kg, total cost — essential for cost reconciliation and audit trail
Frequently Asked Questions
Why is knit fabric sold by weight rather than by length?+
Knit fabric is elastic — the same roll can appear to be different lengths depending on how tightly it is rolled and its tension state at measurement. A tightly rolled knit might measure 90 m but relax to 100 m when spread flat. Weight (kg) is the objective, tension-independent measure that does not change with how the fabric is stored or handled. Bangladesh knit fabric mills invoice by weight; most buyers also specify fabric consumption in their cost sheets as kg/dozen or kg/piece rather than metres per piece for the same reason.
How do I convert fabric price from per-metre to per-kg?+
Price per kg = Price per metre ÷ (GSM × Fabric Width in metres ÷ 1,000). Example: a 160 GSM jersey, 1.5 m wide, priced at $0.57/m: $0.57 ÷ (160 × 1.5 ÷ 1,000) = $0.57 ÷ 0.24 = $2.375/kg. Reverse: Price per metre = Price per kg × (GSM × Width m ÷ 1,000). This conversion is routinely used when comparing quotes from different mills that price in different units, or when checking whether a metre price is competitive with market kg prices.
How do I verify that a supplier is not short-weighting fabric rolls?+
Weigh a representative sample of rolls on a calibrated platform scale on arrival — aim for at least 10% of rolls from every delivery. Compare each roll's actual weight with the weight on the roll ticket and the invoice. Calculate: deviation % = (actual − invoiced) ÷ invoiced × 100. A random variation of ±2–3% is normal. Consistent negative deviations of 2% or more across multiple rolls and deliveries is strong evidence of deliberate short-weighting. Document findings and raise with the supplier in writing, referencing the measured rolls. For a 10,000 kg order, a systematic 2% short-weight means 200 kg missing — at $3.80/kg, that is $760 per delivery.
Does humidity affect fabric weight measurement?+
Yes — all natural fibres absorb atmospheric moisture (termed moisture regain). Cotton's standard moisture regain is 8.5% at 65% RH and 20°C per ISO 6741-1. At higher humidity (common in Dhaka and Chittagong during monsoon), cotton fabric absorbs more moisture and weighs more — which inflates apparent roll weight and can mask short-weighting of actual fibre content. For dispute resolution, condition samples at standard atmosphere (65% RH, 20°C, 24 hours per ISO 139) before weighing. Suppliers sometimes deliver in humid conditions specifically to inflate weight.
How many rolls should I order for a production lot?+
Total fabric weight needed = gross consumption per piece × GSM × fabric width (m) ÷ 1,000 × order quantity × (1 + buffer%). Then divide total weight by average roll weight to get roll count. Add at least 3–5% buffer for: defective sections within rolls, end-of-roll remnants, splicing waste when joining rolls in a lay, and any additional samples required. For a 5,000-piece T-shirt order with 0.336 kg/pc fabric requirement: 5,000 × 0.336 × 1.04 (buffer) = 1,747 kg ÷ 24 kg/roll = 73 rolls minimum. Round up and confirm with your supplier that they can supply all rolls from the same dye lot.