Summary
The benefits of cartonization all come from one decision: which box each order ships in. When software makes that choice per order, right-size packing lowers dimensional weight charges, uses less carton and void fill, removes restacks at the packing station, cuts damage from items moving in the box, keeps parcels inside the EU's 50% empty space limit from 2030, and lets the box and the carrier be chosen together. Across customer deployments, Pulse cartonization ships 15 to 30% less air.
At most pack stations the box is still chosen by eye. A packer who grabs a box that turns out too small loses time on a restack, so the safe habit is to go one size up. The cost of that habit shows up later, on the carrier invoice.
Parcel carriers bill on the higher of actual and dimensional weight. Since 18 August 2025, UPS and FedEx round every fraction of an inch up to the next whole inch, so shipped air costs more than it used to. In the EU, the Packaging and Packaging Waste Regulation (PPWR) has applied since 12 August 2026, and from 2030 it limits how much empty space a parcel may contain.
For the definition and the basics, start with what cartonization is in a warehouse.
Where do the benefits of cartonization come from?
Cartonization decides, before packing starts, which box or boxes an order goes into and how the items sit inside. All six benefits trace back to that per-order box decision. When the box is right, the six cost lines improve together. When it is wrong, each of them loses a little on every order.
Without software the decision is made in one of three ways. Packers choose by eye and go one size up to avoid a restack. A WMS packing rule adds up item volumes and ignores shape, so it proposes boxes the items cannot physically go into and rejects ones they would fit. A fill-rate tool finds a tight box but never looks at what the carrier will charge for it.
Sophie De Vleeschauwer, Solution Design Manager at Van Moer Logistics, which runs e-commerce fulfillment from Belgium, described where they started:
"Previously, we relied on random boxes without considering the specific order profile. Our pickers didn't know in advance how many and which items would fit in a box."
Signs your box decision is costing you
- Carrier invoices show a large share of parcels billed on dimensional weight instead of actual weight.
- Packers swap boxes or repack orders at the station, and nobody counts how often.
- In pick-to-box, pickers walk back to the outbound area mid-route for a different box.
- Void fill is reordered as often as cartons, or more often.
- Nobody can state the fill rate per parcel, which the PPWR empty space rule depends on.
- The box range was chosen years ago and has never been checked against current orders.
The six benefits of cartonization, and how to measure each
You can put a number on each benefit from your own data before you change anything.
1. Lower shipping cost through dimensional weight
Parcel carriers charge on the higher of actual weight and dimensional weight, which is the box volume divided by the carrier's divisor. A light order in a big box is billed for the size of the box.
A 40 x 30 x 30 cm box holds 36 litres. If the order fits in a 30 x 25 x 20 cm box of 15 litres, the larger box bills 21 litres of air. Right-size packing removes that air at the source, before the label prints, which no invoice audit can do afterwards.
The carriers have made oversizing more expensive. Since 18 August 2025, UPS and FedEx round every fraction of an inch up to the next whole inch. A 12.2 x 9.1 x 6.3 inch box is now billed as 13 x 10 x 7: 910 cubic inches against an actual 699, or 30% more billed volume than the carton holds.
The number to pull is on the carrier invoice: the share of parcels billed on dimensional weight, and billed weight against actual weight per parcel. Across customer deployments, Pulse cartonization ships 15 to 30% less air.
2. Less carton and void fill
Air in a box has to be filled, or the items move. More than a quarter of the volume of a typical e-commerce package is air and filler material, according to a box-sizing study in Production and Operations Management (Kandula, Roy and Akartunalı, accepted 2024). Every litre of that is bought, stored at the station, and thrown away by the receiver.
A better-fitted box uses less corrugated and less void fill per order. The figures to track are void fill consumption and carton spend per 100 orders, before and after.
3. Less time at the packing station
Most station time lost to box choice is spent on restacks. The packer loads a box, finds it too small, and starts again. When the box is assigned at order release, the packer starts with a box the items are known to fit.
At Voltex, which runs Pulse for pick-to-box, the saving showed up in freight, packaging and labor at once. Alex Morton, Distribution Technology Lead: "We've had reduced freight cost, reduced packaging cost, and then reduced labor cost by the time saved in every repacking incident we had previously." Voltex walks through its packing setup in a short customer video, and the Voltex customer story explains how its system calls Pulse for every order.
In pick-to-box the effect is larger, because a wrong box costs a walk back to the outbound area as well as a restack. Repacks per 100 orders and seconds per order at the station are the two baseline figures. Pulse also shows packers a 2D or 3D placement plan, so the pack the software found is the pack that gets built.
4. Fewer damaged shipments
Items that cannot move in the box are less likely to break. A right-sized box leaves less room for products to shift and needs less filler to hold them in place.
Packing to maximum fill can backfire for fragile items, so a cartonization engine needs rules: weight and crush limits, this-side-up locks, heavy items at the bottom, and items that may not share a box. Damage claims per 1,000 parcels, split by box type, show whether a tighter range changes the rate.
5. PPWR compliance on empty space
The EU Packaging and Packaging Waste Regulation applies from 12 August 2026. From 1 January 2030, or 36 months after the implementing acts if that is later, e-commerce and transport packaging may contain at most 50% empty space.
Filling materials such as paper cuttings, air cushions and bubble wrap count as empty space, so void fill does not make an oversized box compliant. The ratio also applies per package, which takes product dimensions and a per-parcel fill figure that many warehouses cannot produce today.
Cartonization calculates that figure for every order as a by-product of choosing the box. The share of parcels above 50% empty space today is your gap to 2030. Our PPWR guide for logistics covers the full timeline and the duty of care that falls on 3PLs.
6. Better carrier choice
The cheapest box to fill is rarely the cheapest box to ship. Carrier rates have weight bands, dimensional divisors, size limits and surcharges, and each carrier draws those lines in different places. Sometimes two well-filled boxes cost less than one large one.
In most warehouses the station optimizes for fill and the shipping desk picks a carrier after the box is sealed. Scoring every packing option against every carrier rate makes both choices in one step. Cost-optimal packing explains why the cheapest answer can look wrong at first. Across customer deployments, Pulse lowers transport cost by 10 to 30%.
| Benefit | What changes | What to measure today | Figure to compare against |
|---|---|---|---|
| Shipping cost | Smaller billed volume per parcel | Share of parcels billed on DIM weight; billed vs actual weight | 15 to 30% less air (Pulse, across customer deployments) |
| Carton and void fill | Less corrugated and filler per order | Void fill and carton spend per 100 orders | Over 25% of a typical e-commerce parcel is air and filler (Kandula et al.) |
| Station time | No restacks, box known at release | Repacks per 100 orders; seconds per order | Your own baseline |
| Damage | Less movement inside the box | Damage claims per 1,000 parcels, by box type | Your own baseline |
| PPWR empty space | Fill known for every parcel | Share of parcels above 50% empty space | 50% maximum from 2030 (Regulation (EU) 2025/40) |
| Carrier choice | Box and carrier chosen together | Cost per parcel vs cheapest feasible option | 10 to 30% lower transport cost (Pulse, across customer deployments) |
View this comparison on desktop for the full data table.
You can collect all of these baselines without new software. Carrier invoices, consumables orders, station logs and damage claims already hold them, and two weeks of data is enough for a first read.
Why cartonization benefits often fail to show up
Cartonization projects that disappoint usually fail on one of four points.
Volume math instead of 3D
Many WMS packing modules add up item volumes and compare the total to the box volume, a method called liquid cubing. Volume math ignores shape: a long item will not go into a cube-shaped box of the same volume. The result is restacks when the plan is too optimistic and shipped air when it is too cautious.
Optimizing fill instead of cost
A tool that maximizes fill rate will put an order into one box that crosses a carrier's size threshold. Fill rate only matters when it lowers transport cost. If the engine never sees your rate cards, it cannot see the surcharge it just triggered.
Dimensions nobody trusts
Cartonization depends on the SKU dimensions it reads. If the item master holds supplier estimates, case dimensions instead of unit dimensions, or blanks, the engine plans boxes for products that do not exist in that shape. Measuring the fast movers first usually fixes most of the problem, because they make up most of the orders.
A box range that never changed
Per-order cartonization picks the best box from the range you stock. If the range was bought on rules of thumb, or trimmed to a few sizes for a volume discount, the engine is choosing between poor options. Setting the range from order history is a separate exercise, and its savings come on top of the per-order choice.
What does AI packing add to cartonization?
"AI packing" and "smart cartonization" are used loosely, often for anything with an algorithm in it. In a warehouse packing solution, most of the intelligence is optimization: software that searches a very large number of item placements and box combinations for each order, under hard physical and commercial rules.
The underlying problem is 3D bin packing, and it is NP-hard: the number of possible arrangements grows explosively with every item added. Neither a packer nor a fixed rule can search that space. A packer can fit one order well, and "it fits" is the natural point to stop; the algorithm keeps looking for the arrangement that also ships cheapest.
What smart cartonization does that rules cannot
- Real 3D placement with rotation, including diagonal placement. Pulse places items at an angle where that finds a fit an axis-aligned algorithm misses.
- Physical constraints: weight and crush limits, orientation locks, fragile items on top, and items that may not share a box.
- Cost scoring: every option priced against your own carrier rates, with objectives you rank yourself, for example lowest cost first and highest fill second.
- Envelopes and nesting: flat, light items routed to mailers instead of corrugated, and items placed inside each other where they nest.
- Box range analysis: order history used to recommend which box sizes to stock.
Machine learning is most useful for that last point. The box-sizing study cited above used machine learning to choose an e-commerce company's box sizes, and estimated the saving for that company at about 7.1 million USD a year.
With or without AI, the engine needs clean dimensions, real rate cards and rules that match your operation. It replaces the guess at the station, and the people who know the floor still set the rules.
How to estimate the benefits of cartonization for your warehouse
The fastest way to size the gain is to replay orders you have already shipped. It needs no integration and no change on the floor, and it gives a separate figure for each benefit area.
- Export two to four weeks of shipped orders with order lines, plus SKU dimensions and weights.
- Add your current box range and the carrier rate cards you pay, including surcharges.
- Record today's baseline per area: billed against actual weight, void fill and cartons per order, repacks, damage claims, and the share of parcels above 50% empty space.
- Run the same orders through a cartonization engine and compare box by box and carrier by carrier.
- Check the outliers by hand. Fragile, oversized and very light items are where rules matter most.
Our guide to reducing transport costs with smart packing includes a shipping air audit that works as a quick first pass before a full replay.
Most Pulse cartonization projects start with this replay. Pulse runs cartonization through an API on top of your WMS, ERP or TMS, so the box is assigned when the order is released and the WMS stays in place.
At Van Moer Logistics, which packs with seven box types and two envelope types, each order travels as an EDI message. Sophie De Vleeschauwer describes the loop: "Every order we receive, we first send it as an EDI message to Optioryx's system, after which we immediately receive a message back with information about which products to pack in which boxes."
Van Moer's pickers now know before they start which of the seven box types to take, and they can be sure every item on the order fits. The team used to request more shipping labels from the carrier than it ended up using. With more items fitting into one box, it needs fewer labels. The Van Moer packing case describes the full setup.
SAP EWM users can feed the same box decision into the warehouse task flow. We cover that integration in cartonization in SAP EWM.
Questions?
The main benefits of cartonization are lower shipping cost from smaller billed volume, less carton and void fill, fewer restacks at the packing station, fewer damaged shipments, a per-parcel empty space figure for the EU PPWR, and a box choice that matches the cheapest carrier. All six come from choosing the right box for each order before packing starts. Across customer deployments, Pulse cartonization ships 15 to 30% less air.
Parcel carriers bill on the higher of actual weight and dimensional weight. Cartonization puts each order in the smallest box it physically fits, so less air is billed. Cost-aware cartonization also prices every option against the carrier's rates and size thresholds. Since 18 August 2025, UPS and FedEx round each dimension up to the next whole inch, which makes oversized boxes more expensive.
Smart cartonization uses 3D packing algorithms instead of volume sums or packer judgement to choose boxes. It places items in three dimensions with rotation, respects weight, crush and orientation rules, and scores each option against carrier rates. Some tools, Pulse included, also use order history to recommend which box sizes to stock.
Yes. From 1 January 2030, or 36 months after the implementing acts if that is later, e-commerce and transport packaging may contain at most 50% empty space, and filling material counts as empty space. Cartonization calculates the fill of every parcel while it chooses the box, which gives the per-parcel figure the rule needs and reduces the number of parcels above the limit.
No. Cartonization software assigns a box from your existing range and can guide packers with a 2D or 3D placement plan, so it works at manual pack stations. Box-on-demand machines are optional, and the same software can size boxes for them.