Textile procurement guide
Fabric GSM and Grams per Linear Metre Conversion
Compare fabric weight units with a declared width, then verify the actual finished article through measurement.
Use this guide to prepare a reviewable request. Confirm the selected article or equipment, test basis and responsibilities in the project scope.
Updated October 7, 2026Direct answer
GSM measures area mass; grams per linear metre also depends on width.
GSM means grams per square metre. Grams per linear metre describes the mass of a one-metre length at a stated fabric width. Convert with g/linear metre = GSM × width in metres, or GSM = g/linear metre ÷ width in metres. The calculation assumes a consistent mass and width basis; it does not measure the fabric, establish tolerance or prove garment performance.
Unit conversion tool
Convert GSM and grams per linear metre.
Use the width corresponding to the stated mass. This browser calculation is unit arithmetic, not a measured fabric result or a shipment acceptance check.
Ask what the weight unit and width actually mean.
A quotation headed “weight: 450” is incomplete. Request the unit, whether the value is nominal or measured, the finished article and the width used. GSM and g/m are not interchangeable. A bare g/m label should be clarified as grams per linear metre rather than guessed from a catalogue layout or a photograph.
Use the same width and mass boundary. A whole-width roll mass includes material outside the usable cutting width; dividing that mass by usable width can overstate the GSM of the fabric area being compared. For procurement, record total width, usable width and selvage treatment separately. Request a suitable measured area-mass result when uniformity or contract acceptance matters.
Use the calculation to expose differences in quotation basis.
Illustrative example A: 300 GSM at 150 cm total width gives 300 × 1.50 = 450 g per linear metre. At 140 cm width, fabric with the same 300 GSM gives 420 g per linear metre. The smaller linear mass does not show that the second fabric has a lighter area weight; its area weight is unchanged.
Illustrative example B: 450 g per linear metre at 150 cm corresponds to 300 GSM. The same stated 450 g per linear metre at 140 cm corresponds to about 321.43 GSM. These invented calculation inputs demonstrate units only and are not specifications, prices or available articles from Allot Tech or Fred Textile.
Separate unit conversion from finished-fabric acceptance.
Ask the supplier or laboratory to identify the article and sample, test method and edition, conditioning basis, sampling locations, result and agreed tolerance. Conversion from a nominal linear mass does not replace a test on a defined fabric area. Finishing, moisture condition and variation across a roll can matter when comparing actual measurement results.
GSM alone does not determine warmth, thickness, stiffness, drape or cutting yield. Compare composition, construction, finish, usable width and a physical sample alongside weight. Carry the approved unit and width basis into the purchase specification so a later packing list or inspection report can be checked against the same definition.
The tool supports positive values within its displayed input limits and rounds the displayed result to four decimal places at most. Keep the original supplier values in the comparison record; display rounding is not a production tolerance. Convert centimetres to metres by dividing by 100 before calculating manually.
Keep four fabric quantities separate.
Use consistent units before you compare articles or quotations.
| Quantity | Unit and meaning | What else to record |
|---|---|---|
| Area mass | g/m² (GSM): mass per fabric area. | Finished article, sampling, conditioning and tolerance. |
| Linear mass | g/linear metre: mass of a one-metre length. | Width and whether selvages are included. |
| Roll length | Metres of fabric along the roll. | Measured length method and roll identity. |
| Area-price comparison | Currency per usable m². | Same currency, usable width and commercial price basis. |
Prepare the request
Send the inputs needed to review this requirement.
Article
Code, composition, finish and approved physical sample.
Weight
GSM or g/linear metre, nominal or measured, and agreed tolerance.
Width
Total and usable width with a clear selvage boundary.
Evidence
Sampling and measurement method, conditioning and identified report.
Purchase basis
Price unit, length quantity, development stage and requested delivery.
Reference basis
Primary sources for the technical context.
The checklists are Allot Tech procurement guidance. External manufacturer examples do not establish the capabilities of a quoted Allot Tech configuration.
- ASTM D3776/D3776M: fabric mass per unit area
Official standard-family reference for measured fabric area mass. The linked edition is a reference, not a claim that it is the latest or a substitute for the agreed full test method.
Frequently asked questions
Is 450 g/m the same as 450 GSM?
No. If g/m means grams per linear metre, divide by the stated width in metres to obtain the corresponding GSM. Ask the supplier to clarify an ambiguous unit.
Should I use usable width in every conversion?
Use the width corresponding to the stated mass. Do not divide whole-width mass, including selvages, by a smaller usable width and label the result as measured fabric GSM.
Can the calculator verify a fabric shipment?
No. It checks unit arithmetic. Shipment acceptance requires identified samples, agreed measurement methods and the actual article and roll records.
Project discussion
Discuss this fabric requirement
Include the available specifications, samples or files, project stage and destination so the next review can address the actual requirement.