How to Calculate Overall Line Efficiency

Overall Line Efficiency in Garment Manufacturing: How to Calculate with Formula, Steps & Example

In the garment manufacturing industry, line efficiency is measured on a daily basis to monitor productivity and identify areas for improvement. Among various KPIs used to assess efficiency, Overall Line Efficiency (OLE)—often simply referred to as Line Efficiency—is one of the most important metrics for garment factories.

Overall Line Efficiency measures how effectively a production line utilizes its available time to produce garments according to the standard minute value (SMV). It helps factories understand whether their workforce and processes are operating at optimal productivity or if there are bottlenecks, idle times, or inefficiencies that need to be addressed.

In this post, I will guide you through how to calculate Overall Line Efficiency step by step, including the formula and a practical example from a garment unit.

In garment manufacturing, Overall Line Efficiency (OLE) is a key performance metric that measures how effectively a production line is utilizing its available capacity. High efficiency indicates better productivity, lower costs, and improved delivery performance.

Overall Efficiency in Garment Manufacturing

On the shop floor, operators’ time is not always fully devoted to standard production tasks. Sometimes they work on standard jobs, sometimes on off-standard jobs, and occasionally they may be idle due to lost time (such as unavailability of work).

In a typical 8-hour shift, each operator is allocated 8 standard hours of work. These 8 hours can be divided into three categories:

1. Standard Work Hours – Time spent on regular production tasks according to the SMV.

2. Off-Standard Work Hours – Time spent on activities outside the standard production, such as minor repairs, adjustments, or non-productive tasks.

3. Lost-Time Hours – Time when the operator is idle or waiting due to line stoppages, material unavailability, or other interruptions.

When calculating Overall Line Efficiency, all shift hours are considered without deducting any off-standard work or lost time. This gives a true reflection of how effectively the line’s total capacity is being utilized.

Based on the type of activity, efficiency can also be broken down into:

• On-Standard Efficiency – Efficiency based on standard jobs only.

• Off-Standard Efficiency – Efficiency considering off-standard activities.

Key Point: Overall Line Efficiency measures the productivity of the line as a whole, irrespective of whether the time was spent on standard or off-standard tasks or if there was idle time.

How to Calculate Overall Line Efficiency in Garment Manufacturing

To calculate daily Overall Line Efficiency (OLE), you need to measure two things:

1. How much time (hours or minutes) employees actually spent working on the line

2. The output produced by the line during that time

The efficiency is then calculated based on line output data, using the following formula:

$$\text{Overall Line Efficiency (\%)} = \frac{\text{Line Output × Garment SAM}}{\text{Manpower × Shift Hours × 60}} \times 100$$

Overall Line Efficiency (%)=Manpower × Shift Hours × 60Line Output × Garment SAM​×100

Data Required for Calculation

To calculate overall line efficiency, you need to collect the following four key pieces of information:

1. Line Output – Total number of pieces produced by the line. This could be for one style or multiple styles. For simplicity, we will consider one style in the example.

2. Garment SAM (Standard Allowed Minutes) – Total time required to produce one garment, including machine SAM and manual SAM.

3. Manpower – Total number of workers on the line, including operators and helpers.

4. Shift Hours – Total working hours in the factory for the day. A normal shift is 8 hours.

Once you have collected these four pieces of information, you can apply the formula to calculate the line efficiency in percentage.

Formula to Calculate Overall Line Efficiency

The general formula for Overall Line Efficiency is:

$$\text{Overall Line Efficiency (\%)} = \frac{\text{Actual Output} \times \text{Standard Minute Value (SMV)}}{\text{Total Available Time}} \times 100$$

Where:

• Actual Output = Number of garments produced

• SMV = Standard Minute Value per garment (time required to produce one garment)

• Total Available Time = Total working minutes of the line (number of operators × working hours × 60 minutes)

Step-by-Step Calculation of Overall Line Efficiency

1. Determine Actual Output
   Count the total number of garments produced in a shift or specified period.

2. Find Standard Minute Value (SMV)
   Identify the SMV for the style being produced. SMV represents the time it should ideally take to produce one garment.

3. Calculate Total Available Time
   Multiply the number of operators by the shift duration (in minutes).

   $$\text{Total Available Time (min)} = \text{Number of Operators} \times \text{Shift Duration (hours)} \times 60$$

4. Apply the Formula
   Insert the values into the formula to get the efficiency percentage.

Example Calculation

Scenario:

• A line has 20 operators

• Shift duration = 8 hours

• Actual production = 400 garments

• SMV per garment = 10 minutes

Step 1: Calculate Total Available Time

$$20 \text{ operators} \times 8 \text{ hours} \times 60 = 9600 \text{ minutes}$$

Step 2: Calculate Total Standard Minutes Required for Output

$$400 \text{ garments} \times 10 \text{ min/garment} = 4000 \text{ minutes}$$

Step 3: Apply Efficiency Formula

$$\text{OLE (\%)} = \frac{4000}{9600} \times 100 = 41.67\%$$

Result:

The line efficiency is 41.67%, indicating there is room for improvement in productivity.

Tips to Improve Line Efficiency

• Balance workloads across operators

• Reduce bottlenecks in production

• Provide proper training and motivation

• Optimize layout and material flow