Industrial engineering formula

Manpower requirement formula

Operators needed to meet a daily target at a planned efficiency, grossed up for absenteeism.

Formula

M = \dfrac{Q \times \text{SMV}}{T \times \eta} \times \dfrac{1}{1-a}

Symbol	Meaning	Unit
Q	Daily target	pcs
T	Working minutes per day	min
η	Planned efficiency	-
a	Absenteeism	-

When to use it

Use it when planning a new line or deciding how many operators to add for a higher target.

Worked example#

Target 1,000 pcs, SMV 12, 480 minutes, 65% efficiency, 5% absenteeism.

Present operators = 1,000 × 12 / (480 × 0.65) = 38.46
With absenteeism = 38.46 / 0.95 = 40.49, so plan 41 operators

Where this formula is explained

Industrial EngineeringHow-to5 min read

Line Balancing in Garment Manufacturing: Step-by-Step Method

Line balancing spreads the operations of a garment across operators and machines so work flows at the target rate without piles of WIP or idle people. A practical step-by-step method with a worked example, balancing efficiency and common mistakes.

Industrial EngineeringHow-to3 min read

Production Target Calculation for Sewing Lines

How to set an hourly and daily production target from SMV, manpower, working minutes and planned efficiency. Worked examples for new and running styles, learning curve targets and why a target at 100% efficiency is not a real target.