Weight, accessorials and the last mile · The number the carrier charges on
Billable weight — actual vs dimensional
Carriers charge the greater of actual weight and dimensional weight, then round according to their tariff.
Key facts
| Actual weight | The physical weight of the parcel on a scale |
|---|---|
| Dimensional weight | Volume divided by the carrier's dimensional divisor |
| Rule | Bill on the greater of actual and dimensional weight |
| Rounding | Carriers round up to the next pound or kilogram, or to a fraction, depending on the service |
| Units | Keep inches/pounds or centimetres/kilograms consistent |
| Impact | Light, bulky products are most exposed |
| Official source | Each carrier's published tariff and dimensional-weight policy |
Design the package around the divisor
A few centimetres of empty space can push a parcel into a higher billable weight. If the product is light, reducing the box volume is often the cheapest shipping optimisation available.
Check whether the carrier applies dimensional weight to all services or only above a volume threshold. The same box can be priced differently by service and by destination.
Use the same units everywhere
Mixing inches with centimetres or pounds with kilograms produces a plausible-looking but wrong number. Choose one unit system for the product record and convert only at the carrier interface.
Weigh a packed parcel, not the bare product. Include the box, filler, label and any insert.
Frequently asked questions
Is dimensional weight always used?
Not always. It depends on the carrier, service and parcel size. When it applies, the carrier bills the greater of actual and dimensional weight.
Why does my light parcel cost so much?
It is probably being billed on dimensional weight. Reduce the box volume or check whether a different service has a more favourable rule.
Ask a compliance question
Free first answer by email. Tell us the destination, the product and the channel — we will point you to the rule and the official source. No obligation, no sales sequence.