Free Box Size Calculator for Multi-Item Orders

The smallest carton whose inside dimensions hold every item in some arrangement, while staying under the carton's weight rating. That is harder than comparing volumes: three items totalling 400 cubic inches may not fit a 500-cubic-inch box, because boxes are rigid and orientation matters. This tool actually packs the items — it places each one at a coordinate and checks nothing overlaps — rather than dividing volumes, and it shows you the arrangement it found.

For one item, sort its three dimensions and find the smallest carton that beats all three after sorting. For more than one item there is no formula: you are solving a 3D packing problem, which is NP-hard, and the honest methods are either exhaustive search on small orders or a heuristic that tries orientations in a sensible order. This tool does the second, tells you it is a heuristic, and publishes how often it misses a packing an exact solver finds.

The warehouse term for choosing which box each order ships in, and in which arrangement. It sits between picking and packing: the WMS proposes a carton, the packer either accepts it or overrides it, and the difference between those two shows up as void fill, dimensional weight, and damage. Good cartonization is measured in shipping cost per order, not in fill percentage.

Because you gave it a tolerance. If you tell the tool your measurements are accurate to a quarter inch, it re-packs every carton with each item a quarter inch larger and ranks cartons that survive that test ahead of cartons that do not. A box that only fits if every dimension is exactly right is not a box your packers can use. The result always names the smaller carton it passed over and what it would take to choose it — set tolerance to zero and it will.

Carriers bill the greater of an order's actual weight and its dimensional weight, which is the box's volume divided by a divisor the carrier sets. A low divisor means bulky parcels cost more. This tool never hardcodes a divisor — you supply yours, because they change and they differ by carrier, service and contract. It also asks for your wall thickness, because carriers measure the outside of the box and a carton library records the inside.

Inside. A carton's usable space is what determines whether the order fits, so the library here is inside dimensions, the same convention a WMS carton table uses. Supply your wall thickness separately and the tool converts to outside dimensions for the dimensional weight calculation. If you enter outside dimensions as if they were inside, every answer will be slightly too optimistic.

Accurate enough that the answer does not change, and this tool tells you exactly what that means for your order. For every item and every axis it scans upward from your stated dimension until the carton stops working, and reports the value it packs up to and the value it fails at. If an item has a tenth of an inch of headroom, your master data needs to be better than a tenth of an inch. If it has two inches, it does not.

The tool proposes the smallest change that fixes it, and executes each suggestion against the packer before offering it. That may be a split — and the split names which items go in which box, with each box's weight against its rating, not just a count. It may be a carton size you do not currently stock, built and packed to confirm before it is named. If weight rather than size is the blocker it says so instead of suggesting a bigger box.

Not on its own, and this is the limitation most likely to bite you. The solver places items touching each other at zero separation, which is not how any packer works. The honest workaround takes ten seconds: enter each item at its wrapped size, adding twice the wrap thickness to every dimension, so a 6 x 4 x 2 inch item in a quarter inch of bubble becomes 6.5 x 4.5 x 2.5. Do not use the clearance setting for this — clearance pads the carton walls, not the gaps between items, so it will not stop two wrapped items being placed face to face. And do not use the tolerance setting either: that is how wrong your measurements might be, which is a different question from how much material you deliberately add.

Yes. Mark an item upright and the packer only considers orientations that keep its original height vertical, which is how you encode a liquid, a fragile item, or a THIS SIDE UP label. The tool will never suggest laying that item down to make an order fit — that is a contradiction of a safety constraint, not an optimisation trade-off. You can separately mark an item as not rotatable at all if you want it packed exactly as entered.

It is the same computation, run on one order instead of on your whole order stream. Inside Binlogic the carton library is your real one, the item dimensions come from your master data rather than a form, and the result feeds the pack station rather than a browser. What this page shows is the reasoning: the same solver, with every claim it makes carrying the evidence behind it.