Hoodie GSM explained: fabric weight, garment weight and fit

GSM describes an area of fabric

Fabric weight is commonly expressed as grams per square metre, written g/m² or GSM. AS Colour explains the measurement as fabric mass divided by the area sampled. The unit therefore includes an area; a plain weight in grams is a different measurement.

One square metre of 400 GSM fabric has a mass of 400 grams. The same area of 350 GSM fabric has a mass of 350 grams. The first is about 14.3% heavier per unit area. That calculation does not establish that a finished hoodie is 14.3% heavier, warmer or better made.

Keep fabric, garment and parcel weights in separate columns

A hoodie contains more than one simple square of fabric. Its pattern, size, hood, ribbing, fasteners and other components affect the finished item. A shipping sample can include additional packaging. Those quantities cannot be exchanged just because all contain a weight number.

When a listing shows a warehouse sample weight, retain its stated role. Do not copy it into a GSM field or use it to reverse-engineer a fabric specification without the necessary area and component information.

Compare construction and composition beside GSM

AS Colour’s hoodie guide describes different fabric constructions, including fleece and French terry. Its French-terry explanation identifies loops on the inside, while its published range includes different cuts and fabric weights. This is a useful reminder to read the construction description, not just a large weight number.

The manufacturer’s Heavy Hood specification separately states 400 GSM, a cotton/polyester blend and an oversized fit. Those are distinct fields. That specification belongs to that manufacturer’s product; it is not evidence that a similarly described spreadsheet listing uses the same fabric or pattern.

For a candidate hoodie, request the composition and the inner-face construction if they are missing. Ask whether a stated GSM applies to the main body fabric or a different component. Keep an unavailable answer marked as unavailable.

Use weight labels in their own context

Terms such as midweight and heavyweight are most useful within a clearly described range. AS Colour’s guide labels its 290 GSM and 400 GSM hoodies differently and also describes their respective fits and features. Those examples illustrate one brand’s range; they do not create universal boundaries for every supplier.

When comparing records, keep the actual unit next to the description. If one seller writes only “heavy” and another publishes a GSM value, the first has not supplied the same information. Ask for the missing specification rather than converting the adjective into a number.

Choose the fit with dimensions, not fabric mass

Decide which fit you want before comparing size labels. Measure a similar hoodie that already fits, then compare the candidate’s chest width, body length and sleeve method in the same units. Check dropped shoulders or a cropped body as design features instead of assuming that every difference is a size error.

A GSM value cannot supply a missing chest measurement. Likewise, a body-weight size hint does not show sleeve length. Keep the fabric question and the fit question separate so each has an answer you can inspect.

On the external order page, confirm the chart and selected size for the exact option. If the chart belongs to another style, the fit comparison remains unresolved even when the fabric description looks complete.

Worked comparison: a higher GSM does not fill in a missing size chart

Imagine listing A states 400 GSM but supplies no garment chart. Listing B states 350 GSM and supplies a chart with flat chest width and body length. Both are fictional examples; neither is a product assessment.

A has the higher stated fabric mass per area. B supplies information you can compare with a hoodie that fits. Neither fact proves which hoodie is warmer or better made. If A is your preferred style, ask for its garment dimensions; if construction or composition is missing from B, ask for those fields before judging the fabric.