The short answer
A cubic capacity rule applies when freight takes up a lot of space for very little weight. Like linear foot rules it comes from the carrier’s tariff, and thresholds differ between carriers.
Do these first
Treat space and weight as separate facts.
- Measure all three finished dimensions — cube depends on actual outside size.
- Use actual shipment weight — low weight does not mean low operating cost.
- Check the carrier tariff — cubic rules are carrier-specific.
Why low-density freight creates a different problem
A trailer can run out of usable volume before it reaches its weight capacity.
Light but bulky freight consumes capacity the carrier could otherwise use for other shipments.
That is the operating problem behind cubic-capacity rules.
How this differs from linear feet
Linear foot rules focus on floor length.
Cubic capacity rules focus on three-dimensional space relative to weight.
A shipment can be short in length but still very bulky.
A shipment can also be long without being especially high-volume.
Carrier tariff controls
Published carrier tariffs show different cubic and capacity provisions.
Dohrn and Moran, for example, publish their own rules rather than following one universal industry threshold.
Use the applicable carrier tariff for the shipment.
Sources
- https://www.dohrn.com/wp-content/uploads/2026/01/Dohrn-Rules-Tariff-Effective-1-5-2026.pdf
Shipping light but bulky freight?
Send the finished dimensions, weight and carrier so I can check whether a capacity rule may apply.
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