SMV, or standard minute value, is the time a trained operator needs to complete a task at a normal working pace, including allowances for personal needs, fatigue and small unavoidable delays. It is expressed in minutes.
If the side seam of a T-shirt has an SMV of 0.55, a qualified operator working at standard pace should complete one side seam operation, on average, every 0.55 minutes over a normal working day.
Almost every production number in a garment factory depends on SMV: targets, efficiency, capacity, manpower, line layout and the cost of making. That is why a wrong SMV causes problems everywhere at once.
What SMV includes#
An SMV has three parts:
| Part | Meaning |
|---|---|
| Basic time | The time the work takes at standard pace, without any extras |
| Allowances | Extra time for personal needs, fatigue and small delays that are part of normal work |
| (Sometimes) Contingency | Extra for occasional work such as thread changes or bundle handling, if not already in the method |
The SMV of a garment is the sum of the SMVs of all its operations, from the first sewing operation to the last manual task that the line performs (such as thread trimming or checking), depending on how the factory defines the scope.
How SMV is set#
There are two main approaches.
Time study#
An industrial engineer times each operation with a stopwatch or video, over several cycles, judges the operator's pace against standard pace (the performance rating), then adds allowances:
Time study is quick to start and uses real conditions, but it depends on the observer's rating skill. The full method is in how to calculate SMV and time study.
Predetermined time systems#
Systems such as GSD (General Sewing Data) break each operation into standard motions (get, place, sew a given distance, trim, aside) and add up the standard times for those motions. Time is usually counted in TMU, where 1 TMU is 0.00001 hour, or 0.0006 minutes.
These systems give consistent SMVs before a style reaches the floor, which helps costing and planning. They need trained analysts and licensed software.
Many factories use predetermined systems for costing and planning, and time study to check and improve methods on the line.
What SMV is used for#
| Use | How SMV enters |
|---|---|
| Line efficiency | Efficiency = output × SMV / (manpower × minutes) |
| Production target | Target = manpower × minutes × efficiency / SMV |
| Capacity planning | Orders are converted to minutes (quantity × SMV) and compared with available minutes |
| Manpower and machines | Operation SMVs decide how many operators and machines each operation needs |
| Line balancing | Pitch time = garment SMV / operators |
| CM cost | CM = SMV × cost per minute / efficiency |
| Incentives | Operator efficiency = pieces × operation SMV / minutes worked |
Try the line efficiency calculator and the production target calculator to see how a change in SMV moves both numbers.
A worked example#
A basic T-shirt has these operations:
| Operation | SMV (min) |
|---|---|
| Shoulder join | 0.30 |
| Neck rib join | 0.45 |
| Neck top stitch | 0.40 |
| Sleeve attach (two) | 0.90 |
| Side seam and sleeve seam (two) | 1.00 |
| Sleeve hem (two) | 0.60 |
| Bottom hem | 0.45 |
| Label attach | 0.25 |
| Trim and check | 0.80 |
| Garment SMV | 5.15 |
A line of 20 operators working 480 minutes at 70% efficiency should make 20 × 480 × 0.70 / 5.15 = 1,305 T-shirts per day.
Rough SMV ranges#
Every factory's SMVs depend on construction, fabric, machines and method, so use your own data. As a rough order of magnitude, simple knit tops are measured in single-digit minutes, polo shirts and basic woven shirts in the teens to twenties, and jeans and tailored jackets higher still. A jacket with linings and many pockets can exceed an hour.
Why SMVs go wrong#
- Rating everyone at 100%. The standard then follows the operator you happened to time.
- Timing a new operator or a new style on day one. Learning time is not work content.
- Leaving out manual work. Trimming, turning, marking and bundle handling take real time.
- Copying a buyer's SMV without checking scope. A buyer SMV for costing may exclude work your line actually does.
- Not updating after a method change. A new folder or attachment can cut an operation's time sharply.
SMV and SAM#
SAM (standard allowed minute) is another name for the same idea. Some companies use SMV, others SAM, and a few distinguish them by scope. See SAM vs SMV.
Summary#
- SMV is standard time in minutes: basic time plus allowances.
- Garment SMV is the sum of operation SMVs, and its scope must be clear.
- It drives targets, efficiency, capacity, manpower, balancing and CM cost.
- Set it with time study or a predetermined time system, and keep it up to date.
Build an SMV from time study data with the garment SMV calculator.
Related guides#
- Line efficiency: the most common use of SMV on the line.
- Production target calculation: setting targets from SMV.
- CM cost: costing garments from SMV.