Guide · June 23, 2026
Two charges that sound interchangeable, come from two different parties, and run on two different clocks. Mixing them up is how importers lose track of the bill.
Demurrage and detention are the two charges that quietly inflate a lot of import invoices. They're related, they're both about time, and they get used as if they're the same thing — but they're billed by different parties for different reasons. Knowing which is which is the first step to keeping either one off your invoice.
Demurrage is charged by the terminal for keeping a container inside the terminal past its free time. When your box is discharged from the vessel, it's given a Last Free Day (LFD) — the deadline to get it out. Leave it sitting in the yard past that date, and the terminal charges demurrage, per container, per day. It's the meter that runs while the container is still inside the gate.
Detention is charged by the carrier or container line for keeping their equipment too long outside the terminal. Once you pull the container out, you have a window to unload it and return the empty (or the chassis). Hold it past that window and detention — also called per-diem on the container — starts accruing. It's the meter that runs while the box is out in your possession.
Demurrage = the box sat too long inside the terminal (terminal's charge). Detention = you kept the equipment too long outside it (carrier's charge). Same idea — time costs money — but a different party, a different clock, and a different free-time window for each.
| Demurrage | Detention / per-diem | |
|---|---|---|
| Who charges it | The marine terminal | The carrier / container line |
| What it covers | Container sitting inside the terminal | Equipment held outside the terminal |
| Clock starts | After the Last Free Day | After the free time on the pulled container |
| Billed | Per container, per day | Per container/chassis, per day |
Neither charge is bad luck — both are clocks you can see coming:
This is the daily discipline of good drayage: watch both clocks per container and act before the deadline. For more on the timeline, see what is drayage.
Demurrage is charged by the terminal for a container left inside the terminal past its free time; detention (per-diem) is charged by the carrier for keeping their equipment too long after you've pulled it out.
The marine terminal charges demurrage, per container per day, once the container stays past its Last Free Day.
The carrier or container line charges detention (also called per-diem) when you hold their container or chassis beyond the allowed free time after pulling it from the terminal.
Track the Last Free Day on every container, book terminal appointments against the deadline, plan the unload and empty return early, and pre-pull when your warehouse isn't ready in time.