SAM, cost per minute and line efficiency: the three numbers behind sewing cost
Sewing cost is standard minutes times cost per minute, divided by efficiency. Each of the three is easy to get wrong in a way that makes the garment look cheaper than it is.
Sewing cost has a simple shape: **standard minutes × cost per minute ÷ efficiency**. Three numbers. Each one is routinely wrong, and all three errors push the cost in the same direction — down.
1. Standard minutes: measured, not estimated
SAM is the time the garment should take, operation by operation, at a normal working pace with allowances included. It is the sum of the operation breakdown, not a figure for the whole garment plucked from a similar style.
If you have no time study, the honest fallback is to time the operations on a running line and record that you did. A measured figure with a known method beats a borrowed figure with no method — and it can be improved next season.
2. Cost per minute: what the line actually costs
Total cost of running the line for a period, divided by the productive minutes available in that period. "Total cost" is the part people cut short — it must include:
- Operator wages with all statutory on-costs, not base pay.
- Supervisors, mechanics, quality checkers and helpers — the line does not run without them.
- The share of factory overhead allocated to this line.
Leaving out indirect staff is the usual error, and it is a large one: a line's support headcount is a meaningful fraction of the people standing on it.
3. Line efficiency: the divisor everyone forgets
A line does not deliver its theoretical minutes. Learning curves, imbalance, changeovers, machine stops and absenteeism all take a share, and what remains is efficiency.
Cost sewing at SAM × cost per minute **without dividing by efficiency** and you have costed a factory that does not exist. This is the single most common error in garment costing.
What the three numbers reveal once they are separate
Kept apart, they answer a question a single CM figure cannot: **why** is this garment expensive?
| If the outlier is | The problem is | Where to look |
|---|---|---|
| High SAM | The garment is complex, or the method is | Operation breakdown, attachments, work aids |
| High cost per minute | The line is expensive to run | Indirect headcount, overhead allocation, wage structure |
| Low efficiency | The line is not delivering what it could | Balancing, changeover time, absenteeism, training |
Three different problems, three different departments, three different solutions. Merged into one CM number, they are indistinguishable — and that is why so many cost reduction programs in this industry consist of pressing everyone to work faster.
Where this guide stops
This is about how to measure and record. It does not tell you what efficiency you should reach or what SAM a given garment ought to have — those depend on your machines, your operators and your product mix, and you know them better than any general document.
Related guides
- Garment costing: the ten categories behind a CM price
How a garment cost is actually built — fabric, trims, cutting, sewing minutes, finishing, packing — and why the CM number quoted to a buyer only makes sense once you know what sits underneath it.
- Fabric consumption per garment, and where the fabric actually goes
Fabric is the biggest line in most garment costs. How to get consumption from the marker rather than from memory, what marker efficiency really measures, and the losses that never appear on the marker at all.