Required manpower calculator
How many operators an order needs to be sewn in the working days available, given the garment SMV and the efficiency the line will really run at.
How this is calculated
The order contains quantity × SMV standard minutes. Each operator earns days × hours × 60 × efficiency standard minutes in the period. Operators required = quantity × SMV ÷ (days × hours × 60 × efficiency), rounded up to whole people.
Worked example. 5,000 pieces × 12 min = 60,000 standard minutes. One operator earns 5 × 480 × 0.60 = 1,440 minutes in 5 days. 60,000 ÷ 1,440 = 41.67, so 42 operators.
Quick table: operators needed for an order
Operators needed to sew 10,000 pieces at an SMV of 10, working 8-hour days, for different deadlines and line efficiencies. Rounded up to whole operators. Change any input in the calculator above for your own order.
| Working days | 50% efficiency | 60% efficiency | 70% efficiency | 80% efficiency |
|---|---|---|---|---|
| 10 days | 42 | 35 | 30 | 27 |
| 15 days | 28 | 24 | 20 | 18 |
| 20 days | 21 | 18 | 15 | 14 |
| 25 days | 17 | 14 | 12 | 11 |
Questions
- Why round up rather than to the nearest whole number?
- Rounding down leaves the order short. The exact figure is shown too, so you can decide whether a fraction is better covered by overtime than by an extra operator.
- Does this include absenteeism?
- No. It is the number of operators who must actually be working. If your line runs at 8% absenteeism, roster more people accordingly.
- Does the line balance work out with this many people?
- This is a total-minutes estimate. Whether that headcount can be balanced across the operations depends on the bulletin and the bottleneck operation; use it to size the line, then balance it.
- How do I allow for absence when planning the roster?
- First calculate how many operators must be present. Divide that whole-person count by the expected attendance rate, then round up again. If you need 42 operators present and expect 92% attendance, 42 ÷ 0.92 = 45.65, so roster 46. This covers an average attendance assumption; it does not guarantee the right skills will be available on each operation.
- Which working hours should I enter?
- Use the hours available for the work covered by the SMV. Keep breaks, helper work and downtime consistent with the efficiency figure. If efficiency already includes a loss, do not subtract the same loss from working time as well. Check the result against the operation bulletin and machine capacity before assigning the roster.
- How do I calculate manpower for a garment order?
- Multiply the order quantity by the garment SMV to get the standard minutes in the order. Divide by the standard minutes one operator earns in the time available (days × hours × 60 × efficiency). Round the answer up to whole operators.
- What happens to the headcount if efficiency changes?
- Headcount moves in the opposite direction and by more than most people expect. In the same order, going from 60% to 50% efficiency raises the operators needed by one fifth. Plan with the efficiency the line has achieved on similar styles, not with a hoped-for figure.
- How do I handle overtime?
- Raise the hours per day to include the overtime hours, and check that the efficiency you enter still holds at the end of a long day. Overtime reduces the number of operators needed, but it does not remove the need to check line balance.
- Can I use this for cutting or finishing?
- The identity is the same, but use the SMV and efficiency of that department. A sewing SMV does not describe cutting, pressing or packing work.
Read the full guide
Sources & verification
This is the capacity identity of work study rearranged for headcount (ILO, Introduction to Work Study). The worked example is recomputed in the automated tests.