The inner size is the product size multiplied by the arrangement plus a clearance gap on every side: inner length = product length × count + (count + 1) × gap. The outer size then adds the flute allowance, because corrugated board has real thickness and the box bulges slightly once assembled. A-flute adds roughly 6 mm to length and width and 9 mm to height.

B-flute is about 3 mm thick with a fine profile — it prints well and suits retail packaging. A-flute is about 5 mm and gives more cushioning and stacking strength, so it is the usual choice for shipping cartons. AB-flute is a double wall around 8 mm, used for heavy contents or tall stacks where compression strength matters most.

Two limits decide it: the carton weight and the pallet footprint. Manual handling guidance generally keeps a carton under about 15 kg. Beyond that, a carton that divides neatly into the pallet gives a better load — which is exactly what the Max Load option searches for, testing every arrangement that stays under your weight limit.

RSC stands for Regular Slotted Container, the most common corrugated box. It is made from one blank: four side panels plus a glue tab, with flaps top and bottom. Each flap is half the box width, so the two outer flaps meet in the middle when closed. The dieline this tool draws is an RSC blank, with cut lines in red and crease (fold) lines in blue.

A carton only loads well if its footprint divides into the pallet with little waste. On a 1,100 × 1,100 mm pallet, a carton of 550 × 366 mm tiles almost perfectly, while one a few millimetres larger can drop a whole row and lose 10% or more. Because the carton size follows from the arrangement, changing how many products go in each carton is usually the fastest way to raise the load.

Products are never exactly their nominal size — labels, seams and slight bulging all add a little. Leaving a 2–3 mm gap around each product prevents the case where everything fits on paper but not on the packing line. The gap is included when the carton size is calculated, so it flows through to the outer size and the pallet load.

Red solid lines are cuts, where the blade goes through the board. Blue dashed lines are creases, where the board is scored so it folds cleanly. The shaded tab on the left is the glue flap that joins the last panel when the box is formed. The four flaps top and bottom are each half the box width, so the outer pair meets in the middle when closed.

CBM (cubic metre) is length x width x height converted to metres and multiplied. A 447 x 539 x 135 mm carton is 0.447 x 0.539 x 0.135 = 0.0325 CBM. Always use the outer size, never the inner one, because freight is charged on the space the carton actually occupies. Multiply by the carton count for the shipment total.

A 20ft container takes about 10 standard pallets, a 40ft about 20 to 21. So multiply the cartons-per-pallet figure from this tool by those numbers for a rough container estimate. Floor-loading without pallets fits more but costs far more labour and handling time.

If the product has a this-side-up constraint, such as liquids or aerosols, then yes: untick Any orientation so the tool keeps the carton height vertical. Without that constraint, letting the tool rotate all three axes usually loads more, because a carton lying on its side may divide into the pallet more cleanly.

Overhang is when cartons stick out past the pallet edge. Even 25 mm of overhang can cut a carton compression strength by around a third, because the corners that carry most of the load are left unsupported. It also invites damage in transit. This tool never places a carton past the pallet edge, so the occupancy figure is always achievable.

With Max Load on, the tool optimises for units per pallet, not for a round-looking number. A 447 x 539 mm carton looks arbitrary but can tile the pallet almost perfectly, while a tidier 450 x 550 mm carton may drop a whole row. If you need a specific size, turn Max Load off and enter the arrangement yourself; the tool will show you exactly what that choice costs.