What this tool does
Two numbers decide a product's pack configuration: how many units go in an inner pack, and how many inner packs go in a master carton. The second follows from the first, but it is where the errors live, because a carton count entered once at supplier onboarding propagates into every inventory valuation, every purchase order and every rate card. This calculator multiplies the pack structure out to a carton quantity, works out how many cartons an order needs, and shows what the packing actually costs you in freight volume.
How it works
Units per carton is units per inner pack multiplied by inner packs per master carton. Six units to an inner pack with twelve inner packs to a master carton is 72 units per carton. That multiplication is the whole formula, and it is worth writing into the item master rather than holding in your head, because a 72 and a 96 look identical on a shelf but mean very different things when a customer orders fifty.
Volume efficiency is the part that decides whether a pack structure is any good, and it matters because freight is charged on the cube a shipment occupies and not only on its weight. Straight-sided boxes packed tight can approach 100%, but anything round or irregular loses 20% or more to the air inside the carton. That lost volume is not free: on courier divisor 5000, every 10,000 cm3 of dead air is 2 kg of chargeable weight, whether the goods inside it weigh 2 kg or nothing at all.
Pallet standards are worth getting right, because the most widely quoted EUR pallet size is misquoted constantly. The EPAL/EUR pallet is 1200 x 800 mm, which is 120 by 80 cm and not 120 by 100. The 1219 x 1016 mm figure, 48 by 40 inches, is the US GMA pallet, and the Australian standard is 1150 x 1150 mm. A loading or racking plan built on 120 x 100 will not take a real EUR pallet, and the error only surfaces when someone tries to execute the plan.
Planning a pallet count from carton dimensions takes three steps: divide the pallet length by the carton length and round down, divide the pallet width by the carton width and round down, then multiply. Multiply by the layer count, which is the maximum stack height divided by the carton height, and 180 cm is the common limit. Volume efficiency also decides whether a quantity break is worth taking, because a 72-unit carton at a better unit price can cost more in freight than a 48-unit carton at a worse one if the outer dimensions grow.
Worked example
A 1-litre bottle is 8 cm across and 25 cm tall, standing upright. Six bottles make an inner pack (2 wide by 3 deep) and 12 inner packs make a master carton.
- Inner pack = 2 x 3 = 6 bottles, measuring 16 x 24 x 25 cm
- Master carton = 12 inner packs, arranged 3 x 2 x 2, so 48 x 48 x 50 cm
- Units per carton = 6 x 12 = 72 bottles
- Carton volume = 48 x 48 x 50 = 115,200 cm3 = 0.1152 CBM
- One bottle occupies pi x 4^2 x 25 = 1,257 cm3, so 72 bottles = 90,500 cm3
- Volume efficiency = 90,500 / 115,200 = 78.5%
72 bottles per master carton at 0.1152 CBM and 78.5% volume efficiency. The missing 21.5% is the air between round bottles, and on divisor 5000 that dead air bills as chargeable weight.
Accuracy and limitations
- Carton count is arithmetic, not physics. A pack structure also has to survive a drop test and fit your shelf and racking, and no formula here tells you which inner pack quantity a given carton will actually hold in practice.
- Freight cost depends on the carrier's rate for your lanes, so the CBM figure is what drives any saving rather than a rupee amount. Rate cards vary by zone, weight break and mode.
- Breakage and shrinkage are excluded. A carton that arrives with three broken bottles still consumed the full freight, so damage allowance belongs in the costing, not in the pack structure.
Frequently asked questions
- What is the standard EUR pallet size?
- 1200 by 800 mm, which is 120 by 80 cm. The 120 by 100 cm figure that circulates is the US GMA pallet at 1219 by 1016 mm, and the Australian standard is 1150 by 1150 mm. Three different pallets and one very common mix-up.
- How many units fit in a master carton?
- Multiply the units per inner pack by the inner packs per carton. Six per inner pack with twelve inner packs gives 72 units per master carton, and the calculator also converts that figure into the number of cartons needed for a given order quantity.
- Why do my cartons not fit a full pallet layer?
- Because a carton count that does not divide evenly leaves unusable space, or because the pallet standard in use is not the one assumed. Round down on both axes: 800 divided by 72 is 11.1, so 11 rows, not 12, since a partial row does not go on a pallet.
- How much empty space should a carton have?
- For straight-sided rectangular goods, 5% or less. For round or irregular items, 15-25% is normal and unavoidable, because circles do not tile a rectangle. That gap is still worth measuring, since the dead air is charged as volumetric weight on every shipment.
- Is there a good units-per-carton number?
- There is no universal figure, and anyone quoting one is selling a carton rather than solving your problem. It depends on your product's dimensions, shelf life, picking ergonomics and your supplier's minimum order quantity, and the practical targets are a loadable carton, a quantity that divides cleanly into your customers' order sizes, and an outer size that fills a pallet layer.