A specified length of a given seam is measured and then the thread is pulled out of this length. We can use the amount pulled out of this specified length to calculate the ratio of thread consumed in the entire seam. By dividing the amount of thread by the seam length, we get the ratio of thread consumed. If we multiply this factor times the total length of seam, we can determine the total thread consumed for that seam.

Example:

Length of seam = 100 cm (1 metre)
Stitch class 401 = 2-Thread Chain stitch
Length of seam for which thread is removed = 15 cm
Needle thread removed = 19.5 cm
Needle thread factor = 19.5/15 = 1.3
Looper thread removed = 62.0 cm
Looper thread factor = 62.0/15 = 4.1
Total Needle thread = 100 cm x 1.3 = 130 cm
Total Looper thread = 100 cm x 4.1 = 410 cm
Total thread consumed = 130 + 410 = 540 cm
Add 15% wastage* = 540 cm x 1.15 = 621 cm

*Generally, 10% to 15% wastage of thread is added to the consumption derived. This wastage occurs due to shop-floor conditions like machine running, thread breakage, repairs, etc. The above example shows the total thread consumed for one type of stitch class in a garment. By following a similar procedure, you can calculate the thread consumed for different stitching operations in a garment.