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Technical Bulletin
Estimating Thread Consmuption
Average Thread Consumption Totals by Garment |
Estimating Thread Consumption |
Estimating Thread Cost |
Introduction |
Measuring Actual Thread Consumed |
Thread Consumption Formulas
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Introduction
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 2)
Calculate the cost of the thread needed to manufacture the finished
product.
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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. (Obviously, you must do
this for each seam to determine the total amount of thread consumed in the
finished product.)
Example:
- Length of seam is 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
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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.
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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.
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Union
Special 401 Chainstitch Chart |
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Seam
Thickness |
8
SPI |
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.055
.060
.065
.070
.075 |
4.88
4.96
5.04
5.12
5.20 |
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.
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Calculation (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.
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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.
Example:
- Stitch & seam: 401 SSa-1
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Length of seam: 42 inches or 1.17 yards
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Fabric weight: Light weight
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Estimated Thread Consumption:
- 1.17 yds. X 5.0 (Ratio) = 5.85 yds. /
seam
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5.85 yds/seam X 1.15 = 6.73 yds/seam, including a 15% waste factor
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Estimated needle thread: 6.73 X 40% = 2.69 yds
- Estimated looper
thread: 6.73 X 60% = 4.04 yds
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Stitch
Type |
Est.
Total Consumption Ratio |
Needle
thread |
Bottom
thread |
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301
Lockstitch |
3.0
to 4.0 (1) |
50% |
50% |
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401 Chainstitch |
5.0 to 7.0 |
Lt. Wt. 40% (2) |
60% |
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M. Wt. 50% |
50% |
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H. Wt. 60% |
40% |
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503
Overedge
(2 thread) |
7.0
to 10.0 |
60% |
40% |
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504 Overedge
(3 thread) |
12.0 to 16.0 |
25% |
75% |
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515
Safetystitch
(4 thread) |
12.0
to 17.0 |
55% |
45% |
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516 Safetystitch
(5 thread) |
17.0 to 23.0 |
37% |
63% |
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- Use lower
estimated thread consumption numbers for light-weight fabrics or
long stitch lengths.
- On the
chainstitch construction, the amount of looper thread does not
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.
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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.
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:
- 25% waste factor = 131
yds.
- Average Cost of T-24
Poly Wrapped Core Thread:
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Cost per yard $4,500:
- 6000 yard cone = $.00075/yard
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Calculation:
- 131 yds./shirt X
$.00075/yard = $.09825/shirt
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Product
Sewn |
Total
Yds/
Garment |
Product
Sewn |
Total
Yds/
Garment |
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Men’s |
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Boy’s |
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Slack |
225 |
Jeans |
168 |
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Jean |
200 |
Pants |
183 |
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Jean Short |
160 |
Jacket |
175 |
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Work Pants |
238 |
Dress Shirt |
101 |
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Suit Coat |
175 |
Knit Shirt |
83 |
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Dress Shirt– long sleeve |
131 |
Baseball Cap |
44 |
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Work Shirt |
115 |
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Knit Polo Shirt |
130 |
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Fleece Sweat Shirt |
280 |
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Tee Shirt |
63 |
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Tank Top |
58 |
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Knit Brief |
68 |
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Women’s |
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Girl’s |
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Lined
Coat |
246 |
Blouse |
73 |
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Blazer |
153 |
Dress |
118 |
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Dress |
141 |
Swim Suit |
65 |
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Skirt |
192 |
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Blouse |
122 |
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Pants |
162 |
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Jeans |
250 |
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Shorts |
151 |
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Robe |
300 |
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Night Gown |
135 |
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Panties |
62 |
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Bra |
63 |
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Other
Information |
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Topics |
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Technical Information
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