Every container you ship comes with a clock attached. Two clocks, actually — and when either runs out, the carrier starts charging you daily fees that can quietly exceed the freight cost itself.
Definitions: demurrage vs. detention
- Demurrage — charged when your container sits inside the terminal longer than the allowed free time. Import example: the box is discharged Monday, free time is 5 days, you pick it up the following Wednesday — you owe demurrage for the extra days.
- Detention (per diem) — charged when you keep the container outside the terminal beyond free time: you picked it up, unpacked it, but returned the empty late.
Free time is the grace period before either clock starts — commonly 3–7 days for demurrage and 3–5 for detention, varying by carrier, port and contract. Charges typically escalate in tiers: the first days past free time might be $75–150/day, rising to $300+/day the longer the box sits. On a delayed multi-container shipment, five figures accumulates fast.
Why charges actually happen
Almost never because someone chose to leave a container sitting. The usual causes are information failures:
- The vessel arrived earlier or later than the ETA everyone was working from, so the trucker/broker weren't ready.
- Nobody noticed discharge had happened, so free time burned silently before customs clearance even started.
- Documentation or customs holds that would have been fine with three days' notice became emergencies.
- The empty return deadline was tracked in someone's head, and that someone was on leave.
Seven practical ways to avoid the charges
- Track the vessel, not just the booking — live AIS positions reveal early/late arrivals days before carrier ETAs update. (Vessel tracking.)
- Alert on discharge — the demurrage clock starts at discharge, so that event should page someone, not sit in a portal.
- Pre-clear customs — file before arrival wherever the regime allows; use accurate predictive ETAs to time it.
- Book trucking against live ETAs — not against the ETA from three weeks ago.
- Make the empty-return date visible — a shared dashboard deadline, not tribal knowledge.
- Watch transshipment ports — a missed connection at a hub shifts the whole arrival window; catching it early resets everyone's planning. (Exception management.)
- Keep an audit trail — event timestamps win disputes; carriers do occasionally start clocks incorrectly.
All seven are visibility problems before they're operational ones — which is why a tracking dashboard with alerts, like Shyppy, pays for itself the first time it saves a single day of demurrage.