Estimating Thread
Consumption:
Learn Apparel
Merchandising.
Thread Consumption
Formulas
It is important to
know the amount of thread consumed in a sewn product so you can:
1) 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 is 42
inches or 1.17 yards.
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: 6.63 yards/seam X 1.15 = 7.62 yards/seam including 15% waste
factor.
Obviously, you must do
this for each seam to determine the total amount of thread consumed in the finished product.
Thread Consumption
Formulas
Union Special Machine
Company published a "Thread Consumption Booklet" that consists of
a 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. On some overedge
and coverstitch types it is necessary to also know the seam width or
needle spacing to properly calculate the amount of thread consumed.
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.
|
Union Special 401 Chainstitch Chart
|
|
|
Seam Thickness
|
8 SPI
|
|
.055
.060
.065
.070
.075
|
4.88
4.96
5.04
5.12
5.20
|
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
1.17 yds X 5.20 = 6.08 yds / seam.
6.08 yds/seam X 1.15 = 7.00 yds per seam including a 15% waste
factor.
Estimating Thread
Consumption
As you can see from
the Union Special chart, the more stitches per inch and the thickness of the seam impacts the
amount of thread consumed. However, most heavy fabrics are sewn with fewer
stitches per inch and most light fabrics are sewn with more stitches per inch.
Therefore we have come up with the following estimates based on typical
seam thickness and stitch length.
|
Stitch Type
|
Est. Total
Consumption Ratio
|
Needle thread
|
Bottom
thread
|
|
301 Lockstitch
|
3.0 to 4.0 (1)
|
50%
|
50%
|
|
401 Chainstitch
|
5.0 to 7.0
|
Lt. Wt. 40% (2)
M. Wt. 50%
H. Wt. 60%
|
60%
50%
40%
|
|
503 Overedge (2 thread)
504 Overedge (3 thread)
|
7.0 to 10.0
12.0 to 16.0
|
60%
25%
|
40%
75%
|
|
515 Safetystitch (4 thd.)
516 Safetystitch (5 thd.)
|
12.0 to 17.0
17.0 to 23.0
|
55%
37%
|
45%
63%
|
|
1. Use lower estimated thread
consumption numbers for light-weight
fabrics or long stitch lengths.
change unless the stitches per inch
changes. On the other hand, the
needle thread will change based on
the thickness of the seam.
Therefore, the percentage of
needle thread goes up when the fabric
gets heavier. Lt. Wt. (light
weight) is generally like shirts and
blouses; M. Wt. (medium weight) is
generally like slacks or chinos;
and H. Wt. (heavy weight) is
generally like denim applications.
|
|||
Example:
Stitch & Seam –
401 SSa-1
Length of seam – 42
inches or 1.17 yards
Fabric weight – Light
weight
Estimated Thread
Consumption = 1.17 yds. X 5.0 (Ratio) = 5.85 yds. / seam
5.85 yds/seam X 1.15 =
6.73 yds/seam including a 15% waste factor
Estimated needle
thread = 6.73 X 40% = 2.69 yds
Estimated looper
thread = 6.73 X 60% = 4.04 yds
Average Thread
Consumption Totals by Garment
The following is a
list of sewn products and thread consumption totals based on thread consumption reports
conducted by our Technical Service Department. These thread consumption
figures include a 25% waste factor and are based on a typical garment construction.
|
Product
Sewn
|
Total
Yds/Garment
|
Product
Sewn
|
Total
Yds/Garment
|
|
Men’s
|
Boy’s
|
||
|
Slack
Jean
Jean
Short
Work
Pants
Suit
Coat
Dress
Shirt – long sleeve
Knit
Polo Shirt
Fleece
Sweat Shirt
Tee
Shirt
Knit
Brief
|
225
200
160
238
175
131
115
130
280
63
58
68
|
Jeans
Pants
Jacket
Dress
Shirt
Knit
Shirt
|
168
183
175
101
83
44
|
|
Women’s
|
Girl’s
|
||
|
Lined
Coat
Blazer
Dress
Skirt
Blouse
Pants
Jeans
Shorts
Robe
Panties
Bra
|
246
153
141
192
122
162
250
151
300
135
62
63
|
Blouse
Dress
Swim
Suit
|
73
118
65
|
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
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