SAM (Standard Allowed Minutes) and SMV (Standard Minute Value) are the core building blocks of industrial engineering in garment manufacturing. They define how long each operation — and the complete garment — should take to produce at standard performance. Every other production metric flows from SAM: CM cost, manpower requirement, production target, and line efficiency. This guide explains how SAM is calculated and used.
SAM vs SMV — Are They the Same?
In practice, SAM and SMV are used interchangeably in Bangladesh's RMG industry. Technically, SMV is the observed time converted to standard performance, while SAM adds machine and personal allowances on top of SMV. For most factory purposes, the terms are used as equivalents.
How SAM Is Calculated
SAM is derived from a method study and time study of every operation in the garment. Each operation is timed over multiple cycles, a performance rating is applied, and allowances are added.
Basic Time = Observed Time × (Performance Rating / 100) SAM = Basic Time × (1 + Allowance %) Allowances typically include: - Personal allowance: 5% (toilet breaks, personal time) - Fatigue allowance: 4–8% (varies by task physical demand) - Machine allowance: 2–3% (thread breaks, needle changes) Example: Attach sleeve operation Observed time = 0.85 minutes (average of 10 readings) Performance rating = 90% (operator slightly below standard) Basic time = 0.85 × (90/100) = 0.765 minutes Allowance = 12% (5% personal + 5% fatigue + 2% machine) SAM = 0.765 × 1.12 = 0.857 minutes
Building a Complete Operation Bulletin
The garment SAM is the sum of SAM for every individual operation. An operation bulletin lists each sewing, cutting, pressing, and finishing operation with its SAM. A basic t-shirt might have 15–20 operations; a woven shirt 35–50; a structured jacket 80+. The total SAM drives all downstream planning.
Sample Operation Bulletin — Basic Polo Shirt (Partial)
| Operation | Machine Type | SAM (min) |
|---|---|---|
| Collar join to body | 3-thread overlock | 0.72 |
| Collar topstitch | Flatlock / chainstitch | 0.65 |
| Sleeve hemming | Cylinder bed flatlock | 0.58 |
| Sleeve attach | 4-thread overlock | 0.88 |
| Side seam join | 4-thread overlock | 0.95 |
| Placket attach | Lockstitch | 1.20 |
| Bottom hem | Flatlock | 0.68 |
| Button hole + attach | Special machine | 0.85 |
| Total (simplified) | ≈ 12.5 min SAM |
How SAM Drives CM Cost
Once you have the garment SAM, the CM cost per piece follows directly from the line's hourly cost and efficiency. A higher SAM means fewer pieces per hour and a higher CM cost — which is why buyers push back on complex styles with many operations.
Hourly output per operator = 60 / SAM (at 100% efficiency) Adjusted output = (60 / SAM) × (Efficiency % / 100) CM per piece = Line hourly cost (USD) / (Line operators × adjusted output per operator) Example: SAM = 12.5 min, efficiency = 72%, 40 operators, line cost = USD 55/hr Output per operator/hr = (60/12.5) × 0.72 = 3.46 pieces/operator/hr Line output = 40 × 3.46 = 138 pieces/hr CM = 55 / 138 = USD 0.40 per piece
Tip
When a buyer asks you to reduce CM, do not reduce it by negotiating the rate alone — instead analyse the operation bulletin to see whether any operations can be eliminated, combined, or done on faster machines. A 10% reduction in SAM gives a 10% reduction in CM cost without touching labour rates.