Weight, accessorials and the last mile · The number behind the volume
Dimensional divisor — 139, 166 and 5000
The divisor converts box volume into a billable weight; common values are 139 and 166 for cubic inches per pound and 5000 for cubic centimetres per kilogram.
Key facts
| UPS | Commonly 139 in³/lb for dimensional weight |
|---|---|
| FedEx | Commonly 139 in³/lb for dimensional weight |
| USPS | Commonly 166 in³/lb where dimensional weight applies |
| DHL Express | Commonly 5000 cm³/kg |
| Formula | Length × width × height ÷ divisor |
| Rounding | Round the parcel dimensions and the result according to the carrier tariff |
| Change risk | Divisors and thresholds can change; confirm the current tariff |
| Official source | Carrier dimensional-weight pages |
A larger divisor is friendlier to bulky parcels
Dividing by 166 produces a lower dimensional weight than dividing by 139 for the same box. That is one reason a postal service can be cheaper for a light, bulky item while a commercial carrier wins on speed or tracking.
Do not assume the divisor is the only difference. The service level, size limits, surcharges and delivery network also change the total.
Measure the outer box
Use the outside dimensions of the packed parcel, including any bulge from the contents. Carriers measure what they handle, not the nominal box size on the spec sheet.
If a parcel is near a rounding threshold, a small reduction in one dimension can change the billable weight. Test the actual packed box before committing to a shipping price.
Frequently asked questions
Which divisor does USPS use?
USPS commonly uses 166 cubic inches per pound where dimensional weight applies. Confirm the current rule for the specific service.
Is 5000 the same as 139?
They are close but not identical: 5000 cm³/kg is roughly 139 in³/lb. Use the carrier's own unit system to avoid conversion errors.
Ask a compliance question
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