How to Calculate Standard Allowed Minutes (SAM) Step by Step

Every garment target, every costing sheet and every efficiency report in a factory rests on one small number. It is the time a trained operator needs to make a piece at a normal pace. That number is the Standard Allowed Minutes, or SAM. If it is right, targets are fair and prices are safe. If it is wrong by even five percent, the error runs through everything built on top of it.

This guide shows how to calculate standard allowed minutes from scratch. You will see the formula, the steps of a time study, how rating and allowances work and a full worked example, first for one operation and then for a whole T-shirt. We also show how SAM turns into a line target, an efficiency figure and a cost. For the definition and background, see our existing pages on standard allowed minutes and on SAM versus SMV. This article focuses on the calculation itself.

What SAM means in one paragraph

SAM is the standard time, in minutes, to complete a task or a whole garment, including allowances for rest and unavoidable delay. It assumes a trained operator, working at a normal pace, with the right machine, method and material. Many factories use the terms SAM and SMV (standard minute value) for the same thing. A few use SMV for the basic time without allowances. Always check how your buyer or your factory defines it. Our page on the standard minute value explains the second view.

The formula

Basic time = average observed time × rating ÷ 100

Standard time (SAM) = basic time × (1 + allowance %)

Three ideas sit inside these lines.

• Observed time is what you measure with a stopwatch or a video.
• Rating corrects for the pace of the operator you watched. If the person works at a normal pace, the rating is 100 percent. If faster, it is above 100. If slower, below.
• Allowance adds time for personal needs, fatigue and small delays that cannot be avoided.

The result in seconds is divided by 60 to give minutes.

Step 1: Break the garment into operations

List every operation in the order of work. An operation is a task done by one operator on one machine, such as “join shoulders” or “attach neck rib”. Write a clear description, the machine type, the stitch type and any special tool. This list is the operation breakdown. See our example of an operation breakdown and SMV for a knit T-shirt.

Break each operation into small elements if it is long. Elements make it easier to spot slow steps and to compare methods. A typical element list for “attach sleeve” would be pick up parts, align, sew, trim and place aside.

Step 2: Fix the method before you time it

Time study measures a method. If the method changes, the time changes. Before timing, make sure the operator uses the standard method with the right machine, attachment, needle, thread and stitch density. Also check that the workplace is set up correctly and the material is of normal quality. Timing a poor method produces a poor standard.

Step 3: Choose the operator and the sample

Pick a trained operator who is neither the fastest nor the slowest. Explain that the study is to set a standard for the job and not to judge the person. Observe at least 10 cycles for short operations. For very short cycles, more cycles give a steadier average. For long cycles, fewer may be enough, but never base a standard on one or two readings.

Step 4: Time the cycles

Use a stopwatch, a timing app or a video with a time stamp. Record the time for each full cycle of the operation. If an unusual event happens, such as a thread break, note it and exclude that cycle from the average, as it will be covered by allowances. Note the time for each element too, if you are using element timing.

Step 5: Judge the rating

Rating is the study person’s judgement of the operator’s pace compared with a normal pace. The scale used in industry sets 100 as normal. Some systems use 60-80-100-120 anchors. A rating of 90 means the operator is working at 90 percent of a normal pace. Rating is a skill. It needs training and practice, ideally with reference videos so that different engineers reach similar ratings. Consistency matters more than any single number.

Step 6: Decide the allowances

Allowances are extra time to cover things that are part of real work but not part of the basic task. Common groups are:

Allowance	What it covers	Typical range
Personal	Drinking water, toilet, short breaks	About 4 to 6 percent
Fatigue	Tiring work, long standing, awkward posture, heat	About 4 to 10 percent, depending on conditions
Delay or contingency	Small unavoidable stops such as thread breaks, needle changes, waiting for bundle	About 2 to 5 percent
Bundle or handling	Picking and moving bundles	Often included in the others, or set separately
Machine allowance	Machine-controlled time where the operator waits	Added per operation if relevant
Special	Training, cleaning, setting up	Set by the factory

Total allowances in garment factories are often in the range of 10 to 20 percent. The exact figures differ by factory, buyer standard and country. Use the figure agreed with your management and buyer, and write it in the study.

One caution. Some companies add the allowance on top of basic time (multiply by 1.15 for 15 percent). Others define the allowance as a share of the final standard time (divide by 0.85 for 15 percent). The second gives a slightly higher SAM. Pick one rule and apply it everywhere.

Worked example 1: SAM for one operation

The operation is “attach sleeve” on a knit T-shirt, using a 4-thread overlock machine.

Observed times (seconds) for 10 cycles

52, 55, 50, 58, 54, 53, 51, 56, 55, 54

Average observed time

• Sum = 52 + 55 + 50 + 58 + 54 + 53 + 51 + 56 + 55 + 54 = 538
• Average = 538 ÷ 10 = 53.8 seconds

Rating

The operator worked at a pace judged to be 90 percent of normal.

Basic time

• 53.8 × 90 ÷ 100 = 48.42 seconds

Allowances

• Personal 5 percent, fatigue 6 percent, delay 4 percent, total 15 percent

Standard time (add-on method)

• 48.42 × 1.15 = 55.68 seconds
• In minutes: 55.68 ÷ 60 = 0.928 minutes

Standard time (share-of-standard method)

• 48.42 ÷ (1 − 0.15) = 56.96 seconds
• In minutes: 56.96 ÷ 60 = 0.949 minutes

The two methods differ by about 2 percent. This is why the factory must state its rule.

So the SAM for this operation is about 0.93 minutes with the add-on method.

Worked example 2: SAM for a whole T-shirt

Once every operation has its standard time, the garment SAM is the sum. Here is a sample list for a basic round-neck T-shirt. The figures are illustrative.

No.	Operation	Machine	SAM (min)
1	Join shoulders	4-thread overlock	0.42
2	Make neck rib loop	Lockstitch	0.30
3	Attach neck rib	4-thread overlock	0.95
4	Attach back neck tape	Lockstitch	0.55
5	Topstitch neck	Coverstitch	0.70
6	Attach sleeves	4-thread overlock	0.93
7	Side seam with care label	4-thread overlock	1.10
8	Hem sleeves	Coverstitch	0.60
9	Hem bottom	Coverstitch	0.70
10	Attach main label	Lockstitch	0.35
11	Thread trimming	Hand	0.45
	Sewing SAM		7.05
12	Finishing, iron, check, fold, pack	Hand	1.10
	Total garment SAM		8.15

Check the sum of the sewing operations: 0.42 + 0.30 + 0.95 + 0.55 + 0.70 + 0.93 + 1.10 + 0.60 + 0.70 + 0.35 + 0.45 = 7.05. Adding finishing, 7.05 + 1.10 = 8.15. Cutting is usually counted separately.

From SAM to a line target

The target for a day follows from SAM.

Target = operators × working minutes × efficiency ÷ SAM

Take a line of 25 operators, 480 working minutes and a planned efficiency of 70 percent, using the sewing SAM of 7.05.

• Available minutes = 25 × 480 = 12,000
• Productive minutes = 12,000 × 0.70 = 8,400
• Target = 8,400 ÷ 7.05 = 1,191 pieces

From SAM to efficiency

Efficiency compares the minutes earned with the minutes available.

Efficiency % = output × SAM ÷ (operators × working minutes) × 100

If the line makes 1,000 pieces:

• Earned minutes = 1,000 × 7.05 = 7,050
• Efficiency = 7,050 ÷ 12,000 × 100 = 58.75 percent

From SAM to operators needed

If the plan calls for 1,200 pieces a day at 70 percent efficiency:

• Operators = 1,200 × 7.05 ÷ (480 × 0.70) = 8,460 ÷ 336 = 25.2

So the plan needs 26 operators, rounded up, and the line balance decides how they are spread across operations.

From SAM to cost

If the factory cost per available minute, including wages and overheads, is 0.03 dollars:

• Conversion cost per piece = SAM ÷ efficiency × cost per minute
• At 70 percent efficiency: 7.05 ÷ 0.70 × 0.03 = 0.302 dollars
• At 58.75 percent: 7.05 ÷ 0.5875 × 0.03 = 0.360 dollars

The same garment costs about 6 cents more to make at the lower efficiency. See our guides on how to calculate product cost and factory overheads for the full chain.

Why accuracy matters: a 5 percent error

Suppose the true SAM is 7.05 but a rushed study says 7.40, which is about 5 percent higher.

• The target at 70 percent would become 8,400 ÷ 7.40 = 1,135 pieces instead of 1,191, a drop of 56 pieces a day
• An operator who makes 1,191 pieces would show an efficiency of 1,191 × 7.40 ÷ 12,000 = 73.4 percent, instead of the true 70
• The quoted cost would be too high by 5 percent on the labour portion, which can lose an order

A SAM that is too low does the opposite. It sets targets that nobody can meet, and it hides a loss in prices. Our article on target versus actual production shows how that gap appears on the floor.

Other ways to get SAM

Stopwatch time study is the most direct method, but it is not the only one.

Method	How it works	Notes
Stopwatch time study	Observe and time real operators	Needs trained observers and rating skill
Video time study	Record and time the video	Allows review and training
Predetermined time systems (PTS)	Break the task into basic motions with known standard times, using systems such as MTM or garment-specific data like GSD	Faster for new styles, needs trained users and licensed data
Work sampling	Random observations of activity	Good for allowances and delays, not for operation times
Historical data and style libraries	Reuse SAMs from similar past styles	Quick, but check differences in fabric and details
Software tools	Library-based SAM calculators	Depend on the quality of the library

Many factories use predetermined times for a first estimate in the sampling stage and then confirm with a time study on the line.

Factors that change SAM

• Fabric type, weight and stretch
• Seam length and stitch density
• Machine type, speed and attachments
• Style details such as pockets, plackets, topstitching and trims
• Operator skill and training
• Bundle size, layout and workplace design
• Needle and thread quality
• Buyer quality standards and tolerances

When any of these change, the SAM may need a recheck. A new fabric or a new attachment is a good reason for a new study.

Common mistakes

• Timing one or two cycles and calling it a standard
• Timing the fastest operator and using a rating of 100 anyway
• Mixing the add-on and share-of-standard methods
• Leaving out the allowances
• Forgetting to separate machine time from handling time
• Copying a SAM from a different fabric or style
• Not updating the SAM after a method change
• Using a SAM for sewing only when the buyer expects a total including finishing
• Rating without a reference or training

A simple checklist

1. List and describe every operation.
2. Fix the method, machine and workplace.
3. Choose a trained, typical operator.
4. Time at least 10 cycles for each operation.
5. Remove unusual cycles and average the rest.
6. Apply a rating for pace.
7. Add allowances using one agreed rule.
8. Convert to minutes and sum for the garment.
9. Check against similar past styles and buyer data.
10. Record the study and review it after the first production run.

Final thoughts

Learning how to calculate standard allowed minutes gives you control over targets, efficiency and cost. Fix the method, time enough cycles, rate honestly, apply one clear allowance rule and add the operations up. Then check the figure against the first production run and correct it. A SAM that people trust makes the whole factory easier to plan.

Frequently asked questions