Common production measures and their formula.
In the apparel industry, industrial engineers, production managers and production planners measure the factory performance on daily basis by following standard formula for each measure. You might be already using such formulas for calculating your factory performance. For example, industrial engineers
 prepare OB sheet,
 measure key performance indicators (KPIs)
 prepare daily reports on factory performance, and
 line performance in terms of productivity and efficiency.
As these are common measures in apparel production, most of the factories use excel templates preparing such reports and calculations where the excel template are prefilled with formula. We just follow the report template. We don’t need to calculate every time we make a report. So, many times we are not clear about how to calculate a particular measure.
Let’s discuss 10 basic production measures and formula used calculating those measures.
1. Hourly production target
Hourly production target = (60 / Operation SAM)
Note: This target is calculated at 100% efficiency. In case you want to plan hourly production target at certain percentage, multiply the above by line efficiency / individual operator efficiency based on your need.
In the table1 few examples are shown for calculating hourly production target at 100% efficiency.
We measure individual operator’s performance (efficiency %) for operator grading, skill matrix, and daily employee performance reporting. In case you are distributing performance based incentives to individual operators, you need to measure individual operator efficiency too. This is the formula to calculate individual operator efficiency.
Total hours worked by the line = Number of operators X Shift hours
Machine productivity is measured as production per machine per shift day. See the following example (Table5).
Standard time is the time allowed to an operator to carry out the specified task under specified condition and defined level of performance. This is a standard definition for standard time. Some additional time is added to basic time to arrive standard time of a task. In practice none can work throughout the day without taking rest. Operators need time for relaxation from fatigue. Various allowances are relaxation allowance, contingency allowance (like machine breakdown) and bundle allowance (for PBS system).
Machines and equipment are primary resources of garment manufacturing unit. These resources must be utilized as much as possible to improvise factory performance. But due to work unavailability or less work, some machines (like specialized machines) are partially utilized by the factory. In such case, same machine is shared for multiple lines. Machine utilization is calculated using below formula.
Production capacity is measured in available minutes as well as in number of pieces. First we will see how available minutes in a line are calculated. Then we will calculate capacity in number of pieces.
Table6: Example of production capacity calculation
Like other garment manufacturing units, you might be also measuring some key production measures to keep track of production performance and controlling the production. Whatever measures and formula you are using must be standardized and approved by the authorized person internally. Also everyone in an organization should be aware how the particular measures are calculated. It is good to have a poster of commonly used formulas and keep the poster in your work space. A poster would be helpful for learning for newcomers.
Note: This target is calculated at 100% efficiency. In case you want to plan hourly production target at certain percentage, multiply the above by line efficiency / individual operator efficiency based on your need.
In the table1 few examples are shown for calculating hourly production target at 100% efficiency.
Table1: Examples of hourly target calculation
Like the hourly production target, daily production target of a line is calculated. This target is given to line supervisors. Based on the daily production target production planning and total production time needed to complete an order is calculated. Following formula is used to calculate daily line target.
Sl. No.

Operation

SAM

Hourly Target (60/SAM)

1

operation1

0.78

76.92

2

operation2

0.85

70.59

3

operation3

1.2

50.00

4

operation4

0.9

66.67

2. Daily Line Target
Like the hourly production target, daily production target of a line is calculated. This target is given to line supervisors. Based on the daily production target production planning and total production time needed to complete an order is calculated. Following formula is used to calculate daily line target.
Daily Line Target = (Shift hours X 60 X No. of operators working in a line X Line efficiency %) /Garment SAM
See the example in the following table
Table2: Daily production target calculation
Table2: Daily production target calculation
Line no

Manpower

Shift hours

Average line eff%

Garment SAM

Daily production Target

1

40

8

65%

30

416.0

2

40

8

60%

24

480.0

3

42

8

62%

42

297.6

4

46

8

58%

38

337.0

3. Individual operator efficiency
We measure individual operator’s performance (efficiency %) for operator grading, skill matrix, and daily employee performance reporting. In case you are distributing performance based incentives to individual operators, you need to measure individual operator efficiency too. This is the formula to calculate individual operator efficiency.
Individual operator Efficiency% = (Total minutes produced*100/Total minutes worked)
Where,
Total minutes produced = Total units produced X operation SAM
See the following examples (table3) for calculating individual operator efficiency. In case an operator is doing more than one operation, first calculate total minutes produced in each operation and sum up total minutes produced in all operations by an employee.
Table3: Examples of individual operator efficiency calculation
Line efficiency is the common measure for measuring line performance and factory performance. Performance of a production line vary depending on operators’ skills, product design, line balancing, presence of lost time, style run time and many other factors. A better efficiency means higher output and reduced production cost. So we aim to improve line efficiency as much as possible. Line efficiency is calculated using following formula.
See the following examples (table3) for calculating individual operator efficiency. In case an operator is doing more than one operation, first calculate total minutes produced in each operation and sum up total minutes produced in all operations by an employee.
Table3: Examples of individual operator efficiency calculation
Sl. No.

Operators

Operation

SAM

Unit produced

Hours worked

Efficiency%

1

Operator1

operation1

0.78

500

8

81%

2

Operator2

operation2

0.85

480

8

85%

3

Operator3

operation3

1.2

300

8

75%

4

Operator4

operation4

0.9

480

8

90%

4. Line Efficiency
Line Efficiency% = (Total minutes produced *100) / (Total hours worked * 60)
Where, Total minutes produced by the line = Line output X Garment SAM
Total hours worked by the line = Number of operators X Shift hours
Table4: Examples of line efficiency calculation
Note: Include helpers and worker doing manual operations in the manpower, in case SAM of the manual operations are included in garment SAM.
The above mentioned formula is used majorly used for line efficiency calculation. This is known as output based line efficiency. Line efficiency can be also measured in a different way. Instead of line output data, individual operators produced minutes and hours worked are calculated first and later their produced minutes and hours worked are summed up to calculated line’s produced minutes and total hours worked. To many this is not easy to calculate individual operators output, their total produced minutes and actual hours they worked in a day. Following the second method is only practical if a factory is using real time production tracing system.
Machine productivity is measured to know the average production per machine per day or in the defined time frame. A line with 48 machines producing 480 shirts and another line with 36 machines producing 400 shirts (same design). How do you figure out which line doing better? This can be answered simply by measuring machine productivity.
Productivity is the ratio of output and input. Machine productivity of a production line is calculated using following formula.
Machine Productivity= Line output / No. of machine used
Sl. No.

Line

Style

SAM

Units produced

No. of manpower

Hours worked

Efficiency%

1

Line1

Style1

24

400

25

8

80%

2

Line2

Style2

30

480

35

8

86%

3

Line3

Style3

12

300

20

8

38%

4

Line4

Style4

20

500

35

8

60%

Note: Include helpers and worker doing manual operations in the manpower, in case SAM of the manual operations are included in garment SAM.
The above mentioned formula is used majorly used for line efficiency calculation. This is known as output based line efficiency. Line efficiency can be also measured in a different way. Instead of line output data, individual operators produced minutes and hours worked are calculated first and later their produced minutes and hours worked are summed up to calculated line’s produced minutes and total hours worked. To many this is not easy to calculate individual operators output, their total produced minutes and actual hours they worked in a day. Following the second method is only practical if a factory is using real time production tracing system.
5. Machine Productivity
Machine productivity is measured to know the average production per machine per day or in the defined time frame. A line with 48 machines producing 480 shirts and another line with 36 machines producing 400 shirts (same design). How do you figure out which line doing better? This can be answered simply by measuring machine productivity.
Productivity is the ratio of output and input. Machine productivity of a production line is calculated using following formula.
Machine Productivity= Line output / No. of machine used
Machine productivity is measured as production per machine per shift day. See the following example (Table5).
Table5: Example of machine productivity calculation
Productivity is also measured as labour productivity. Instead of machine input in this case line output is divided by labour input to calculate labour productivity.
Sl. No.

Line

Machines used

Production

Machine productivity

1

Line1

48

480

10

2

Line2

36

450

12.50

3

Line3

36

420

11.67

6. Labour Productivity
Productivity is also measured as labour productivity. Instead of machine input in this case line output is divided by labour input to calculate labour productivity.
Labour Productivity = Line output / No. of total manpower (operators +helpers)
7. Standard Time Estimation
Standard time is the time allowed to an operator to carry out the specified task under specified condition and defined level of performance. This is a standard definition for standard time. Some additional time is added to basic time to arrive standard time of a task. In practice none can work throughout the day without taking rest. Operators need time for relaxation from fatigue. Various allowances are relaxation allowance, contingency allowance (like machine breakdown) and bundle allowance (for PBS system).
Standard Time = (Observed time X observed rating) + Allowances
Allowances includes Relaxation allowance, contingency allowance
The basic constituents of standard time are shown in the following chart. This chart shows how standard time is made up from observed time and basic time of a job.
Chart1: This chart shows how standard time is made up. Source: Introduction to work study by ILO
The basic constituents of standard time are shown in the following chart. This chart shows how standard time is made up from observed time and basic time of a job.
8. Machine utilization percentage
Machines and equipment are primary resources of garment manufacturing unit. These resources must be utilized as much as possible to improvise factory performance. But due to work unavailability or less work, some machines (like specialized machines) are partially utilized by the factory. In such case, same machine is shared for multiple lines. Machine utilization is calculated using below formula.
Machine utilization% = (Actual machine running time X 100) / Time available
If you are running one of your special machines only 4 hours in 8 hours day, utilization of that particular machine would be 50%.
Labour cost is part of garment FOB. For every order we have a target labour cost. We need to track the actual labour cost and control it. So we measure it after a style is loaded. Here is the formula to calculate labour cost per garment.
If you are running one of your special machines only 4 hours in 8 hours day, utilization of that particular machine would be 50%.
9. Labour cost per unit
Labour cost is part of garment FOB. For every order we have a target labour cost. We need to track the actual labour cost and control it. So we measure it after a style is loaded. Here is the formula to calculate labour cost per garment.
Labour cost pet unit = (Total cost incurred in labour wages / No. of garments produced) in a day
10. Production capacity
Production capacity is measured in available minutes as well as in number of pieces. First we will see how available minutes in a line are calculated. Then we will calculate capacity in number of pieces.
Line capacity per day= {(No. of machine x daily work hours x 60)*(1 – absenteeism %)} x Efficiency % (capacity in minutes)
Production capacity (in pieces) = Available minutes / Garment SAM
Production capacity (in pieces) = Available minutes / Garment SAM
Table6: Example of production capacity calculation
No.

No. of Machines

Minutes/Day (Daily working Hrs. X 60)

Line Efficiency

Absenteeism %

Capacity available (in minutes)

Garment SAM

Production capacity (pieces)

Line 1

30

480

60%

10%

7776.00

15

518.40

Line 2

28

480

72%

8%

8902.66

20

445.13

Line 3

32

480

65%

9%

9085.44

20

454.27

Line 4

32

480

55%

10%

7603.20

20

380.16

Conclusion:
Like other garment manufacturing units, you might be also measuring some key production measures to keep track of production performance and controlling the production. Whatever measures and formula you are using must be standardized and approved by the authorized person internally. Also everyone in an organization should be aware how the particular measures are calculated. It is good to have a poster of commonly used formulas and keep the poster in your work space. A poster would be helpful for learning for newcomers.
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