Key takeaways
- Demurrage: the container overstays inside the terminal after arrival. Detention: you keep the container outside the terminal too long after pickup.
- Free time defines both; the Last Free Day is the deadline before demurrage begins.
- Charges escalate and stack, and they usually surface only when the invoice lands.
- Nearly every charge comes from finding out too late — early, portfolio-wide free-time visibility is the real fix.
The one-sentence difference
Demurrage is charged when your container sits inside the terminal too long after arrival. Detention is charged when you keep the container outside the terminal too long after picking it up. Demurrage is about the box overstaying at the port; detention is about the box overstaying at your yard.
When each clock starts and stops
Both charges revolve around free time — the number of days the carrier or terminal allows before fees begin.
- Demurrage runs from roughly when the container is discharged and available until you outgate it. Free time here is set by the terminal or carrier and is often just a few days.
- Detention runs from when you outgate the loaded container until you return the empty. This free time covers unloading at your facility and getting the empty back.
- The Last Free Day (LFD) is the deadline before demurrage begins. It is the single most important date to watch after arrival.
Why the charges add up so fast
Both fees escalate. A terminal might charge a modest rate for the first day or two past free time, then step it up sharply. A handful of containers stuck a few extra days each can turn into a five-figure bill, and it happens quietly — nobody sends an alert until the invoice arrives.
The costs also stack. A container can rack up demurrage at the terminal and, once collected late, detention on the equipment. The same delay bleeds into both buckets.
How to avoid them
Almost every demurrage and detention charge traces back to the same root cause: the team found out too late. The fixes are operational, not clever:
- Know the Last Free Day before the vessel arrives, not after. Surface it the moment discharge is expected.
- Clear holds early — customs, line release, and unpaid fees are the usual reasons an available box cannot be picked up.
- Book drayage against the availability window, not the arrival date. A container discharged Friday but unavailable until Monday burns weekend free time.
- Turn empties around quickly and return them to the correct location to stop detention.
- Watch the whole portfolio, not one box at a time — the container you are not thinking about is the one that overstays.
None of this requires predicting the future. It requires seeing free-time risk across every active container in one place, early enough to act. That visibility is worth far more than the software costs.
A note on accuracy
Exact demurrage and detention outcomes depend on the terminal, the carrier, your specific contract, and local operating rules. A visibility tool can surface the milestones and free-time context that let you prioritize — it should not pretend to compute a guaranteed fee. Treat the alert as a prompt to verify, not a final number.
Frequently asked
Can I get demurrage and detention at the same time?
Not on the same segment, but a single delayed container can incur demurrage while it sits at the terminal and then detention once you collect it late and hold the equipment too long. The same underlying delay drives both.
Who sets free time?
Free time is set by the carrier and terminal and varies by port, contract, and equipment type. It is often only a few days, which is why watching the Last Free Day closely matters so much.