Fabric weight from the weave, when nobody will tell you the GSM

If you have the tape denier and the mesh count, the fabric weight follows. This is the formula used on the factory floor.

GSM = (warp denier × warp mesh + weft denier × weft mesh) ÷ 228.6

Worked example. 1000 denier tape at 12 × 12 tapes/inch: (1000 × 12 + 1000 × 12) ÷ 228.6 ≈ 105 g/m².

Use it in reverse to check a claim: if a supplier offers 12 × 12 at 1000 denier and calls it 80 g/m², one of the three numbers is wrong.

Next: turn that GSM into a bag weight.