Merge or ship separately: two totals side by side
Decide whether combining parcels saves freight, once the volume discount, reinforcement fees and any storage overage are counted.
Merge planner result
Merging saves 56.00 (24.9% of shipping separately).
Saving rate 24.9%
7.00 kg charged across 2 parcel(s), 222.00 of freight plus 3.00 of reinforcement.
6.00 kg charged at a 0.85 volume factor.
| Parcel | Actual kg | Volume kg | Charged kg | Freight | Reinforcement |
|---|---|---|---|---|---|
| Parcel 1 | 3.00 | 4.00 | 4.00 | 122.00 | 0.00 |
| Parcel 2 | 3.00 | 2.50 | 3.00 | 100.00 | 3.00 |
The merged parcel is billed on its weight: 6.00 kg against 5.53 kg of volume.
How the calculation runs
Parameters and the date they were checked
Parameters checked 2026-10-06. The defaults on this page are the values we recorded when we last read the relevant pages, and they are listed with the same date on the sources page. Change any rate, fee or day count and the tool labels itself manual, so a figure you supplied is never mistaken for one we recorded.
Three ways to use it
- Enter each parcel the way it arrives at the warehouse: actual weight, box sides in centimetres, and the reinforcement fee quoted for that parcel if there is one.
- Leave the volume discount factor at 0.85 for a normal repack. Raise it towards 1 when boxes keep their shape, and lower it when items are soft and compress well.
- Set the storage days to the number you expect, not the number you hope for. A merged parcel keeps everything in the warehouse until the last item lands, so the free window is measured from the first arrival.
Questions this tool gets
When is merging the wrong move?
When the volume discount factor is low and the reinforcement fee is high at the same time. A low factor means the merged box barely shrinks, so the volumetric side keeps charging for the same space, while the reinforcement fee is paid once on a larger, heavier box. The tool prints that verdict when both conditions hold.
Why does the merged parcel sometimes charge on actual weight?
Because merging adds weight but not always volume: once the combined actual weight passes the discounted volume weight, the scale decides again. That is why the two cards can be close even when the boxes look very different in size.
Where it stops being reliable
Boundaries and exceptions
- Fewer than two parcels returns an error: the question this tool answers only exists from two parcels upward.
- A volume discount factor above 1 is rejected as meaningless, since a merged box cannot take more space than the boxes it was built from.
- A combined actual weight above 30 kg is flagged with the suggestion to split the shipment, because most lines stop quoting per kilogram at that point.
- Storage overage is estimated from the days you enter at the daily rate you enter. It is not a quote: overage rules and rates differ per warehouse and are checked on the warehouse pages.
Stops that use this number
- Stop 4: The warehouse clock — Arrival starts a clock. Verify the window on your own account before you plan around it.
- Stop 6: Merge and pack — Merging trades a second freight charge for a bigger volumetric weight. Run both sides.
Readings behind it
- The storage clock: when free days turn into a fee — The clock starts on the arrival date and is counted on the space a parcel takes, not its weight.
- Chargeable weight without the guesswork — Chargeable weight is the larger of the scale reading and the volume divided by the line’s divisor.
- Three hauls, three merge timings, three totals — Merging three light parcels into one saves 0.53 billable kilos at divisor 6000 and 0.40 at 8000.
Other tools: all nine. The reading protocol and the cost waterfall are the two tools that exist only on this site.