12 Useful Formula for Industrial Engineers in Garment Manufacturing (Poster)

I love formulas for mathematical calculations. Because a formula helps me get the result quicker and it specifically mentions all data I need to collect to find the result of the desired thing. In this post, I have shared 12 important garment production formulas for engineers.

garment IE formula

In garment manufacturing, industrial engineers, production managers, and planners measure factory performance on a daily basis. Performances are measured using standard formulas. I guess you are already using such formulas for calculating performance.

Don't you think, it would be a good idea to have a poster of commonly used formulas in your workspace? A poster is a very useful tool for many reasons. I have made one poster for you and sharing it with you.

The following are the common formulas those are used by garment industry professionals.

Formula#1: Calculating the daily production target of a line

Daily Line Target = (Total shift hours X 60 X No. of operators in a line X Line Efficiency%)/Garment SAM

Here is an example to understand this calculation. 
Daily shift Hours of a factory = 8 Hours
Number of operators working in that line= 30 operators
Average Efficiency of that line: 60% 
Garment SAM: 20 Minutes

Production target of this line (Daily) = (8 X 60 X 30 X60%)/20
                            =(480 x 30 x60) / (100 X20)
                            = 432 Pieces 

Read another example for calculating the production target.

Formula#2: Operator-wise production target calculation 

Individual operator target = (Total working minutes in a day X Line Efficiency %)/Operation SAM

In Formula #1, you have the formula for calculating the daily production target for a line. 
But operators working in that line will be working on different operations and the SAM of those operations will be different. 

So, you need to calculate individual operator targets as well based on Line efficiency and operation SAM. 

Refer to this example for the calculation operator target for the specific line.  

Factory shift: 8 Hours (480 Minutes)
Line efficiency = 60% (considering it is the same line in formula#1)
Operation SAM: 0.5 Minutes
Production target of that operator: (480 Minutes x 60%)/0.50
                = (480 X 0.60)/0.5
                = 576 Pieces per 8 hours per day.

In case you use operator performance level (efficiency%) and operation SAM and calculate the production target of that operator, the result is called the operator's production capacity.
Normally, an operator-wise target is not given based on the individual operators' performance, instead, it is calculated based on the line efficiency. See the below example of the operator's capacity. 

Factory shift: 8 Hours (480 Minutes)
Operator efficiency = 80%
Operation SAM: 0.5 Minutes
Production capacity of that operator: (480 Minutes x 80%)/0.50
                = (480 X 0.80)/0.5
                = 768 Pieces per 8 hours per day.

Read more about the operator's target calculation. 

Formula#3: Calculating operator efficiency

Individual operator Efficiency% = (Units Produced X Operation SAM X 100)/Total minutes worked

When you develop the skill matrix for sewing operators you need to measure individual performance. 
Secondly, if you plan to start a performance-based incentive scheme for the individual operator, measuring individual operator efficiency is essential.

Let's say you need to calculate the efficiency of an operator based on the last production day's data. 
Operator Produced total unit: 500 pieces 
SAM of the operation: 0.60 Minutes
The operator worked: 480 Minutes (full shift hours)

Operator Efficiency     = ((500 x 0.60)/480 )X100 

Formula#4: Line efficiency

Line Efficiency% = (Line output X Garment SAM X 100)/(Number of operators X Minute worked in a day)

Note: Include helpers and workers doing manual operations in case you have included SAM of those operations.

Line A produced 600 units (Style Z)
SAM of style Z is 20 Minutes
Attendance in Line A = 30 Operators
Shift Time: 8 Hours

Line Efficiency (Overall Efficiency%)= (600 x 20 x 100)/(30X8 x60)
    = (1200000/14400)
    = 83.33%

Here is another example of line efficiency calculation.
Note: include helpers and workers doing manual operations in case you have included SAM of those operations.  See an example of line efficiency calculation.

Formula#5: Machine productivity

Machine Productivity: (Line output / No. of machine used in producing those garments) 

Machine productivity is measured in production per machine per shift day. In this article, I have discussed more about machine productivity calculation with examples.

Considering Line A has production of 600 units. 
Numer of sewing machines used: 27 Machines

Machine productivity:
                        =  (600/27)
                        = 22.22 units per machine 

Formula#6: Labour productivity

Labor Productivity = Line output / No. of total manpower (operators +helpers)

Considering Line-A has production of 600 units
Numer of sewing operators used: 30 and helpers 5. Therefore labor productivity
                = (600/35)
                = 17.14 units per labor


Line WIP (work in process) = Total pieces lying on the line for a particular order line 

WIP of the line of an order is equal to the total pieces loaded till date minus Total pieces out till date. The WIP calculation method and Excel report template are shown in this post.

Standard Time = (Observed time X observed rating) + Allowances
Allowances – Relaxation allowance, contingency allowance

Machine utilization% = (Actual Machine running Time X 100) / Time available

Cost per minute = Total cost incurred in labor / Total available working minute in a day X no. of labors

Production Cost per unit = Total cost incurred in production in a day/ no. of garment produced in a day

Man to Machine ratio = Total manpower of the factory / Total no. of sewing machines (utilized)
Learn more about Man to Machine Ratio.

Poster Download: 
12 useful performance measuring formulas (Click to enlarge the image and save the image file).

To download the poster save the image after clicking on it.

Note: Our purpose is to provide you with correct information. Still, if you find any formula that is not correct you may comment in the below comment box.

Prasanta Sarkar

Prasanta Sarkar is a textile engineer and a postgraduate in fashion technology from NIFT, New Delhi, India. He has authored 6 books in the field of garment manufacturing technology, garment business setup, and industrial engineering. He loves writing how-to guide articles in the fashion industry niche. He has been working in the apparel manufacturing industry since 2006. He has visited garment factories in many countries and implemented process improvement projects in numerous garment units in different continents including Asia, Europe, and South Africa. He is the founder and editor of the Online Clothing Study Blog. He lives in India. linkedin

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