Stop guessing garment costs. A step-by-step guide to calculating Standard Allowed Minute (SAM), applying ILO allowances, and determining precise manufacturing costs.
Why “Time” is Your Most Expensive Raw Material
In garment manufacturing, fabric is expensive, but time is volatile. If you estimate that a shirt takes 12 minutes to sew, but it actually takes 15, you have lost 20% of your production capacity before the line even starts.
Standard Allowed Minute (SAM) is the only metric that matters. It converts the chaos of human labor into a fixed, calculable number.
For the Industrial Engineer (IE), getting this number wrong means the factory either loses money (under-costing) or loses orders (over-quoting). Here is how to calculate it with zero ambiguity.
The Math: From Stopwatch to Standard
Many IEs get confused when converting “Observed Time” to “Basic Time.” Let’s break it down with a real-world example.
The Scenario: We are measuring the operation “Collar Run Stitch”.
- Operator: John (A highly skilled, fast operator).
- Stopwatch Reading (Cycle Time): 0.60 minutes.
If we just use 0.60 minutes as the standard, the average operator will fail. John is fast; the standard needs to be achievable by everyone.
Step 1: Calculate Basic Time (The Normalization)
We must “normalize” John’s speed to a standard pace (100%).Since John is fast, we rate him at 110% (or 1.1).
Basic time = cycle time x performance rating
Basic time= 0.6 min x 1.1 = 0.66 min
The Logic: Because John was working faster than standard, the “Basic Time” for a normal worker is higher (0.66) than John’s actual time (0.60).
Step 2: Apply Allowances (The Human Factor)
No one works 60 minutes an hour. Operators drink water, change bobbins, and experience fatigue. We add Allowances to the Basic Time.
- Machine Allowance: 5%
- Personal & Fatigue: 10%
- Total Allowance: 15%
SAM = Basic time + ( Basic time x Allowance% )
SAM = 0.66 + ( 0.66 x 15%)
SAM = 0.759 minutes
Result: Even though John sewed it in 0.60 minutes, the Standard Allowed Minute for costing is 0.759 minutes.
Standard ILO Allowances Table
Do not guess your allowances. Use strict standards to maintain credibility with buyers.
| Allowance Type | Percentage | Context |
| Personal | 5% | Fixed. For restroom and hydration. |
| Fatigue | 4% – 6% | Variable. Increase for standing ops or heavy fabric (denim). |
| Machine Delay | 3% – 5% | For bobbin changes and thread breaks. |
| Contingency | 1% – 2% | Buffer for supervisor instructions. |
The Financial Impact: Calculating Cost Per Piece
This is where SAM connects to the profit margin. Once you have the SAM, you multiply it by your factory’s Cost Per Minute (CPM).
How to find your Factory CPM:
CPM = Total monthly operational cost / Total available minutes
Real Calculation:
- Total Cost: $100,000 (Salaries, Rent, Electricity, Overheads).
- Total Minutes: 200,000 minutes (25 days x 400 mins x 20 lines).
- CPM: $100,000 / 200,000 = $0.50 per minute.
Costing the Garment: If the Men’s Shirt has a total SAM of 20 Minutes:
Labor cost = 20 (SAM) x $ 0.50( CPM) = $ 10.00 per shirt
The Risk of Error: If you skipped the rating normalization and used John’s raw time (0.60 instead of 0.759), your total SAM might have looked like 16 minutes.
- Calculated Cost: 16 * $0.50 = $8.00
- Actual Cost: $10.00
- Result: You lose $2.00 on every single shirt.
Final Takeaway: Engineering Over Estimation
SAM is not just a number for the production board; it is the financial anchor of your factory. A variation of decimal points in your time study can lead to massive losses in your P&L.
Next Step: Now that you have calculated accurate SAMs, you need a system to manage them. Read our The Textile ERP Buyer’s Guide to see how to integrate these targets into digital production planning.
For a broader look at efficiency strategies, return to the The Ultimate Guide to Textile Manufacturing
