Thread Consumption Formulas & Practical System For Knit Garments

It is important to know the amount of thread consumed in a sewn product so you can:

Estimate the number of cones needed and calculate the cost of the thread needed to manufacture the finished product. Thread consumption can be determined in several ways.

To calculate the amount of thread in a seam, you can:

• Measure the actual amount of thread consumed in a specific length of seam.

• Calculate the thread consumption by using mathematical stitch formulas based on the thickness of the seam and the number of stitches per inch.

• Calculate the thread consumption using thread consumption estimates.

Measuring Actual Thread Consumed

A specified length of the seam, for example 3 inches, is measured on the seam and then the thread is removed by carefully unraveling the stitch. You can then calculate the amount of thread consumed in one inch and multiply this factor times the total length of the seam measured in inches.

Example:

Length of seam= 42 inches or 1.17 yards.

Stitch and seam construction: 401 SSa-1.

Specified length of thread removed from a seam equals= 3 inches.

Needle thread removed = 9 inches

Looper thread removed = 8 inches

Calculation:

Needle thread factor = 9/ 3 = 3 inches of needle thread per inch of seam.

Looper thread factor = 8/ 3 = 2.67 inches of looper thread per inch of seam.

Total needle thread consumed = factor 3 X 1.17yds = 3.51 yds

Total looper thread consumed = factor 2.67 X 1.17yds = 3.12 yds

Total Thread = 3.51 + 3.12 = 6.63 yards per seam.

Generally, a 15 to 20% waste factor is added due to chaining-off, thread breaks, repairs, etc.

If a waste factor of 15% is selected then, 

Total Thread= 6.63 yards/seam X 1.15 = 7.62 yards/seam

Obviously, you must do this for each seam to determine the total amount of thread consumed in the finished product.

Technical Thread Consumption Formulas

Thread Consumption depend on number of thread consumption formulas for various stitch types based on the stitch length and thickness of the seam. These mathematically derived consumption factors can be multiplied times the length of the seam to estimate the combined amount of top and bottom thread.

Example:

Stitch and seam: 401 SSa-1

Stitches per inch: 8

Thickness of the seam: .075 inches (measured with a micrometer)

Length of the seam: 42 inches or 1.17 Yds.

Consumption based on the mathematical equation:

C = 4 + 2TS

C = 4 + 2(.075 X 8) = 5.20

T = Thickness of The Seam

S = Stitches Per Inch

Actual Required Thread= 1.17 yds X 5.20 = 6.08 yds / seam.

Total Thread required= 6.08 X 1.15 = 7.00 yds/ seam (15% waste factor)

Practical Thread Consumption System:

Seam Length (Inch) x M/C wise Thread per Inch

Thread Consumption = ----------------------------------------------------------------------- + Wastage%

39.37 (Convert in Meter)

Machine Wise Sewing Thread Consumption Per Inch

Sewing thread consumption depending on type of Machine:
 

Example:

Length Side Seam= 42”

Machine = Over Lock- 4 Thread

 42 x 18

Thread Consumption = ------------------ (1+ 7%)

    39.37

                                    = 20.5 Meter

After this you must include another 15% sewing thread before place the work order.

Estimating Thread Cost

The thread cost can be estimated by multiplying the thread consumed times the cost of thread in the same units. 

For example:

Men’s Dress Shirt thread consumption with 25% waste factor = 131 yds.

Average Cost of T-24 Poly Wrapped Core Thread = $4.50 / 6000 yard cone.

Cost per yard = $4.50 ¸ 6000 = $.00075/yard

Calculation: 131 yds /shirt X $.00075/yard = $.09825/shirt

Sewing Thread Consumption per Body

Sewing thread consumption is very important for the garments costing. For quick costing we use our previous idea to calculate the sewing thread cost. Please find below an approximate sewing thread consumption list for some common item. This list is based on minimum wastage. So, at first please check your percent of wastage & and try to control it.