What is Capacity Planning
Capacity planning is the process of calculating how much production a factory can handle in a given period and then matching that capacity to the incoming orders. In garments, capacity is usually measured in pieces per day, per line, or per machine. Good capacity planning prevents late shipments, reduces overtime, and helps the factory quote realistic lead times to buyers.
How to Calculate Capacity
Basic capacity equals number of machines times available hours times efficiency divided by SMV. For example, 30 machines, 8 hours shift, 60 percent efficiency, and SMV of 5 minutes gives 30 times 8 times 60 divided by 5 equals 288 pieces per day.
Practical Example 1 — Single Line
A line with 30 machines runs 8 hours at 65 percent efficiency with an SMV of 4 minutes. Capacity is 30 times 8 times 60 times 0.65 divided by 4 equals 2340 pieces per day. If the buyer orders 50,000 pieces, the line needs 21.4 days, so plan 22 days plus buffer.
Practical Example 2 — Full Factory
A factory has 10 lines, each with 30 machines. Total capacity is 10 times 2340 equals 23,400 pieces per day. Monthly capacity over 26 days is 608,400 pieces. Before accepting orders, compare total booked pieces against this number.
Practical Example 3 — Style Change
A new style has SMV of 6 minutes instead of 4. Same line capacity drops to 1560 pieces per day. Capacity planning must account for SMV changes when mixing styles.
Practical Example 4 — Peak Season
In peak season, factory works 10 hours per day and 6 days a week. Capacity rises, but overtime cost and fatigue rise too. Capacity planning should also plan for realistic efficiency loss, not just the theoretical maximum.
Steps in Capacity Planning
First, calculate the base capacity per line. Second, collect all confirmed and forecasted orders. Third, allocate orders to lines and time slots. Fourth, compare load against capacity. Fifth, identify overloaded or idle periods. Sixth, adjust by overtime, subcontract, adding lines, or rescheduling orders.
Key Factors That Affect Capacity
SMV of the style, skill level of operators, absenteeism, machine breakdown, style change frequency, layout, material availability, and quality rejection rate. A factory that ignores these factors always misses its plan.
Common Mistakes
Using theoretical efficiency instead of actual history. Ignoring absenteeism. Not updating SMV after style change. Accepting more orders than the factory can deliver. Not reserving buffer for rework or breakdowns. Not coordinating with merchandising and production together.
Capacity Planning Tools
Excel is the most common tool. Simple spreadsheets with columns for line, style, SMV, machines, hours, efficiency, and daily pieces are enough for most factories. Larger factories use ERP or specialized software like Fast React, Coats, or GSD-based systems.
When to Use It
Capacity planning is used before order confirmation, during monthly production planning, during style changeovers, and during peak season. It is a core skill for IE, production planning, and merchandising teams.