Exporters and wholesalers ship products in master cartons: larger outer cartons holding several retail packs. The master carton size affects handling, freight cost, damage rates and how many units fit in a container. This guide explains how to plan a master carton size step by step, using our free Carton Size Calculator.
Start with the inner pack
Measure the retail pack or inner box. Decide how many units go in each master carton, often 6, 12, 24 or 48, according to buyer requirements.
Arrange the units
For 24 units of 10 × 8 × 5 cm, possible arrangements include:
| Arrangement (L × W × H) | Inner size (cm) |
|---|---|
| 4 × 3 × 2 | 40 × 24 × 10 |
| 3 × 4 × 2 | 30 × 32 × 10 |
| 2 × 3 × 4 | 20 × 24 × 20 |
Choose the one closest to a cube-like shape with a stable base; it uses less board and stacks better.
Weight limits
Most buyers and warehouses limit manual-handling cartons to around 20 to 25 kg. Heavier cartons cause injuries and damage. Check gross weight with the Package Weight Calculator.
Pallet fit
Cartons should fit neatly on standard pallets (1,200 × 1,000 mm or 1,200 × 800 mm) without overhang. Overhang weakens boxes and causes damage. Test with the Pallet Loading Calculator.
Board grade
Export master cartons usually use 5-ply (double-wall) corrugated board, especially for heavy goods or long sea journeys. Read about grades in 3-ply vs 5-ply vs 7-ply.
Container fit
A few centimetres can change how many cartons fit in a 20 ft or 40 ft container. Run the numbers with the Container Loading Calculator before finalising carton size.
Marking and labels
Master cartons typically show product code, quantity, gross and net weight, dimensions, carton number (e.g. 1 of 120), origin and handling marks. See packaging label symbols.
Approval
Send a sample carton to the buyer for approval before mass production.
For counting units per carton, read how many products fit in a carton.
Frequently asked questions
What is a master carton?
An outer shipping carton that holds several inner or retail packs.
What is a safe weight for a master carton?
Generally under 20 to 25 kg for manual handling.
Which board is used for export cartons?
Usually 5-ply double-wall corrugated board.