Enter fabric construction details

Result

Enter knit construction details

Result

Formula used (knit)

Why different sites show different constants

Search any "GSM formula" online and you'll find calculators using 23.5, 23.25, 25.537, or 0.2327 as "the" constant — with no explanation. They are not actually different formulas. They are the same physics, expressed with different rounding and unit assumptions during the imperial-to-metric conversion. Here is the full derivation so you can see exactly where each number comes from.

Where do these numbers come from?

This is the source of the "23.25" or "23.5" constant you see in most formulas — it is simply this fixed conversion bundle, sometimes rounded up to 23.5 for simplicity.

Note: 23.25 becomes 0.2325 here because crimp% is applied as a (100+crimp)/100 multiplier rather than as a separate addition — same result, cleaner to compute in one pass.