by **Wiz.au** » Wed Jan 07, 2009 11:15 am

Knight (William?), you need to be careful that you haven't used an "area" calculation for Thread Count.

Thread count is defined as the number of horizontal threads per measure, _ADDED_ to the number of vertical threads per measure. It is a "Count" of lines, not intersections as an "Area" or "Volume" calculation is.

Example:

A weave of 120 vertical threads in 1 inch and 150 horizontal threads in 1 inch gives the "Thread Count" of 270TC/SqIn (NOT 18,000)

In metric countries it has become the standard to use "10SqCm" (A square measuring 3.16cm x 3.16cm) instead of the "Inch Square" (A square measuring 2.54cm x 2.54cm) for Thread Count, mostly due to marketing reasons, as it makes the product look higher quality compared to the Imperical measurement.

So you would first have to find the number of threads per cm and extrapolate from this.

So from the example above:

120 vertical threads per Inch becomes

47.244 threads per cm => 144 Threads per 3.16cm

_ADDED_ to

150 horizontal threads per Inch becomes

59.06 Threads per cm => 187 Threads per 3.16cm

Giving a total Thread Count of

106TC/SqCm or 331TC/10SqCm

Your calculation gives the result of 41.86 which is incorrect.

The quick method used by a lot of textile mills is a conversion rate of 1.25 which in my example above gives a Metric Thread Count of 337TC/10SqCm from the orginal 270TC/SqIn, which is close enough for their grades. (80TC, 120TC, 140TC, 180TC, 200TC, 300TC, 400TC, 500TC,...)