Plan a cable gland shipment from the packed product outward: quantities determine cartons, products and packaging determine gross mass, and the final shipping units determine measured volume. Calculate these separately before applying the carrier’s charging rule. Product mass alone cannot predict the freight invoice, and the sum of loose-carton volumes may differ from a pallet’s external shipping envelope.
The example below is a hypothetical order, with stated packing and quotation inputs. You can replace each input with your own approved packing schedule. It contains no current freight rate or universal volumetric factor.
Freeze the SKU and packing schedule
The packing schedule starts with an exact supplied unit. A gland body, a complete gland assembly and a gland with a locknut and sealing washer can have different masses and packing quantities. Match the unit-mass record to what the purchase order actually includes.
| Example SKU | Ordered units | Units per carton | Product mass per supplied unit | External carton dimensions |
|---|---|---|---|---|
| A | 1,250 | 100 | 0.085 kg | 40 × 30 × 25 cm |
| B | 420 | 60 | 0.140 kg | 50 × 35 × 30 cm |
For this example, SKUs cannot share a carton and a partly filled carton retains its normal external dimensions. Those are packing assumptions, not properties of cable glands. If you permit mixed cartons, list each carton’s actual contents instead of rounding separate SKU totals and then mixing them afterward.
Keep lot identities, accessory counts and any permitted quantity variance with the schedule. Also record how unit mass was obtained: a controlled drawing estimate, supplier declaration or weighing of the defined supplied assembly. A preliminary estimate remains an estimate until the final packed shipment is weighed.
Calculate full cartons and the final partial carton
For an order quantity and a positive whole-number packing quantity , total carton count is:
Full cartons number , and the remainder is . A zero remainder means there is no additional partial carton; it does not mean the last full carton is empty. An order of zero units requires zero cartons.
SKU A needs 12 full cartons and one carton containing 50 units: 13 cartons. SKU B needs seven full cartons: 7 cartons. The shipment therefore contains 20 cartons and 1,670 supplied units.
We can cross-check our order against the carton contents: 12 × 100 + 50 = 1,250 and 7 × 60 = 420. That catches a common spreadsheet mistake—using the rounded carton count to reconstruct the ordered quantity and inadvertently creating 50 extra units of SKU A.
If a smaller approved box is used for the remainder, create a separate carton-type row with its own tare and dimensions. You cannot reduce freight volume merely by labeling the original box “half full.”
Add packaging once to obtain gross mass
Net product mass is the sum of each SKU quantity multiplied by its defined unit mass:
Here, SKU A contributes 106.25 kg and SKU B contributes 58.80 kg, giving 165.05 kg net product mass. Use kilograms consistently. The NIST SI conversion tables provide conversions when source records use other mass or length units.
The example packaging belongs in separate, non-overlapping rows:
| Mass item | Calculation | Added mass |
|---|---|---|
| Empty A cartons | 13 × 0.60 kg | 7.80 kg |
| Empty B cartons | 7 × 0.80 kg | 5.60 kg |
| Bags, partitions and other internal packing | Recorded total for this order | 2.50 kg |
| One pallet | Recorded tare | 20.00 kg |
| Wrap, straps and corner protection | Recorded total | 1.20 kg |
| Total packaging | Sum of the five rows | 37.10 kg |
Gross shipment mass is therefore 165.05 + 37.10 = 202.15 kg. These are invented example inputs, not catalogue masses or measured shipment results.
Keep the measurement boundary explicit. If a packed-carton weight already includes its bags and partitions, do not add those materials a second time. If the loaded pallet has been weighed as one unit, that reading already includes the pallet and its wrapping. Retain the calculated breakdown as a reconciliation check and investigate a material difference from the final scale reading.
Calculate CBM from the shipping unit’s external dimensions
CBM means cubic metres. For rectangular packages, multiply external length, width and height after converting all three to metres. With dimensions in centimetres:
The example A cartons occupy 13 × 0.40 × 0.30 × 0.25 = 0.3900 m³. The B cartons occupy 7 × 0.50 × 0.35 × 0.30 = 0.3675 m³. Their summed external carton volume is 0.7575 m³.
That sum describes the cartons individually. If the order is tendered as one pallet, request the carrier’s measurement rule for that handling unit. Suppose its final measured external envelope, including pallet and protection, is 1.20 × 1.00 × 1.10 m. The pallet envelope is 1.3200 m³. It includes the spaces within the stack and the pallet height, which are absent from the sum of carton volumes.
The assumed envelope is a shipment-planning input; the carton arrangement, stack strength and securing method still need their own approval. Do not replace the measured envelope with an ideal volume simply because it produces a lower quotation. Measure protrusions and bulging packaging using the service’s stated method.
Apply the carrier’s factor and rounding rule
DHL’s chargeable-weight guide distinguishes gross shipment weight, including packaging and pallets, from dimensional weight. It also explains that density ratios can vary by mode and carrier. The actual quotation identifies the applicable rule; a divisor from another service may use a different basis.
For a service that charges the greater of actual mass and volume multiplied by a factor in kg/m³:
Suppose this example’s hypothetical quotation specifies 200 kg/m³, applied to the whole pallet before any stated billing rounding. The volumetric mass is 1.32 × 200 = 264 kg, which exceeds 202.15 kg. The preliminary chargeable mass is therefore 264 kg. The factor is an example quotation input, not a recommended or universal carrier conversion.
The calculator implements the comparison above. It does not decide whether the carrier rates each parcel separately, rounds dimensions before multiplication, imposes a minimum charge, or adds non-stackable or oversize charges. If comparison is per package, calculate each package first and then sum; taking the maximum only after aggregating can give a different result. A container-based quotation may use another charging basis entirely.
Reconcile the packing list and quotation
Before booking, compare the worksheet with the actual packed order: SKU totals, 20 carton identities, net mass definition, gross scale reading, pallet count and final external dimensions. Every change to accessories or packing can affect more than one field.
Record the named transport service, route, quotation date, measurement and rounding rules, currency, minimums and included charges. Handling symbols under ISO 780:2015 communicate package handling instructions; they do not establish carton strength or a freight rate.
When comparing offers, use the same delivery boundary and packing assumptions. The cable-gland quotation comparison guide explains how freight and included accessories fit into the broader purchase comparison. I would resolve an unexplained mass or volume discrepancy before treating two freight totals as equivalent.
Conclusion
A reliable shipment worksheet keeps the quantity, mass and volume calculations traceable to the same packed order. In this example, 1,670 supplied units become 20 cartons; their net product mass and packaging produce a different quantity from their carton volume or pallet envelope. Those distinctions make the quotation inputs reproducible.
Your next step is to replace the example assumptions with the approved packing schedule, then reconcile the final measured load with the carrier’s written charging rule. That preserves the usefulness of the calculation when the carton size, accessory pack or transport service changes.
FAQ
Does a partial carton count as a full carton for volume?
Use its actual external dimensions. A normal carton containing fewer glands still occupies its normal envelope. If packing uses a smaller approved carton, record that box as a separate carton type. I would never multiply the regular carton volume by its percentage fill unless that calculation is specifically for internal space utilization.
Is gross shipment mass the same as chargeable weight?
No. Gross mass describes the physical packed shipment. Chargeable weight is a billing quantity under a particular service rule and may be based on dimensional weight instead. I keep the gross scale result and the carrier calculation in separate fields, together with the applicable factor, measurement basis, rounding and minimum-charge conditions.
Can I use one unit mass for all cable gland sizes?
Only if that value actually represents each supplied unit being counted, which should not be assumed across different sizes or accessory packs. Calculate each SKU using its own documented unit mass and then add the results. If only an estimate exists, identify it and reconcile the estimate with final packed weighing before shipment.
Why can pallet CBM exceed the sum of carton CBM?
The pallet’s external shipping envelope includes its base, protection, spaces between cartons and any unused space within the measured outer dimensions. The sum of individual carton volumes omits those features. I use whichever shipping-unit measurement the quotation requires and retain both figures with clear labels when they serve different planning purposes.
Sources and technical references
- DHL — Calculating Chargeable Weight by Air, Ocean, Road and Rail, accessed 2026-10-22.
- NIST — Guide to the SI, Appendix B.9: Conversion factors by quantity, accessed 2026-10-22.
- SIS — ISO 780:2015: Distribution packaging handling and storage symbols, accessed 2026-10-23.