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    Industrial Engineering Formulas for Garments

    Every core IE formula in one searchable place — SMV, efficiency, takt time, capacity, target and manpower — with worked examples for garment and textile production.

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    Industrial Engineering Formulas

    Standard time study, capacity, efficiency and line balancing references.

    Time Study
    7

    Observed Time (OT)

    No Pro Certification

    OT = Σ Cycle Times ÷ Number of Cycles

    Average of the recorded cycle times for one operation.

    Basic / Normal Time (BT)

    Professional Certification

    BT = Observed Time × Performance Rating

    Rating of 100% = standard pace.

    Standard Time (SMV)

    Professional Certification

    SMV = Basic Time × (1 + Allowance %)

    Typical garment allowance: 15–20%.

    Allowance Time

    No Pro Certification

    Allowance = Basic Time × Allowance %

    Covers personal, fatigue and delay (PFD).

    Cycle Time from SMV

    No Pro Certification

    Cycle Time (sec) = SMV × 60

    SMV is expressed in minutes.

    Coefficient of Variation (CV)

    Professional Certification

    CV % = (Standard Deviation ÷ Mean) × 100

    Lower CV = more consistent cycles.

    Number of Observations

    Pro Certification + Featured

    N = ((40 × √(NΣx² − (Σx)²)) ÷ Σx)²

    ±5% accuracy, 95% confidence level.

    Capacity & Output
    6

    Capacity per Hour

    No Pro Certification

    Capacity/hr = 3600 ÷ Cycle Time (sec)

    Machine or operator theoretical output.

    Capacity with Allowance

    Professional Certification

    Capacity/hr = (3600 × Efficiency %) ÷ Cycle Time (sec)

    Realistic achievable output.

    Target per Hour

    Professional Certification

    Target/hr = (60 ÷ SMV) × Efficiency % × Operators

    Line target for one operation.

    Daily Output

    No Pro Certification

    Output = Target per Hour × Working Hours

    Excluding breaks and downtime.

    Takt Time

    Pro Certification + Featured

    Takt = Available Time ÷ Customer Demand

    Pace required to meet demand.

    Pitch Time

    Pro Certification + Featured

    Pitch = Total SMV ÷ Number of Operators

    Also called average station time.

    Efficiency & Productivity
    6

    Line Efficiency

    No Pro Certification

    Efficiency % = (Total Produced × SMV) ÷ (Operators × Working Minutes) × 100

    Core garment line KPI.

    Operator Efficiency

    Professional Certification

    Efficiency % = (Earned Minutes ÷ Available Minutes) × 100

    Earned minutes = output × SMV.

    Labour Productivity

    No Pro Certification

    Productivity = Total Output ÷ Total Manpower

    Pieces per operator.

    Machine Productivity

    No Pro Certification

    Productivity = Total Output ÷ Number of Machines

    Pieces per machine.

    Overall Equipment Effectiveness

    Pro Certification + Featured

    OEE = Availability × Performance × Quality

    World-class benchmark ≈ 85%.

    Utilisation

    Professional Certification

    Utilisation % = (Actual Run Time ÷ Available Time) × 100

    Excludes idle and downtime.

    Line Balancing
    6

    Bottleneck

    No Pro Certification

    Bottleneck = Operation with the Highest Cycle Time

    Line output is limited by this station.

    Line Balancing Efficiency

    Professional Certification

    LBE % = (Total SMV ÷ (Stations × Bottleneck Time)) × 100

    Target ≥ 85%.

    Balance Loss

    Professional Certification

    Balance Loss % = 100 − Line Balancing Efficiency %

    Idle time distributed across stations.

    Theoretical Minimum Stations

    Pro Certification + Featured

    Nmin = Total Task Time ÷ Takt Time

    Round up to the next whole number.

    Smoothness Index

    Pro Certification + Featured

    SI = √(Σ (Max Station Time − Station Time)²)

    Closer to 0 = better balanced.

    Work-in-Progress

    Pro Certification + Featured

    WIP = Throughput × Lead Time

    Little's Law.

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    Most-used garment IE formulas

    • SMV = Basic time × (1 + Allowance %)
    • Line efficiency % = (Output × SMV) ÷ (Operators × Minutes) × 100
    • Takt time = Available time ÷ Demand
    • Capacity per hour = 3600 ÷ Cycle time (s)
    • Target per hour = (60 ÷ SMV) × Operators × Efficiency

    Where these numbers come from

    SMV values usually come from GSD, PMTS, MTM-2 or MOST systems, or from a time study on the floor. ProdEnhancer's AI video analysis calculates them from a short video so you don't need to memorize code tables.

    Frequently asked questions

    How do you calculate SMV?

    SMV = basic time × (1 + allowance %). Basic time = observed time × performance rating ÷ 100. For an observed time of 0.50 minutes at 90% rating with 15% allowance, SMV = 0.45 × 1.15 = 0.52 minutes.

    What is takt time?

    Takt time = available production time ÷ customer demand. If a line has 480 minutes and must ship 960 pieces, takt time is 0.5 minutes (30 seconds) per piece.

    How do I calculate target per hour?

    Target per hour = (60 ÷ SMV) × operators × target efficiency. For a 0.8 SMV operation, 1 operator and 75% efficiency: 60 ÷ 0.8 × 0.75 = 56 pieces per hour.

    How many operators does a line need?

    Required operators = (target output × SMV) ÷ (working minutes × expected efficiency).

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