Demurrage and detention: how free days work and how to stop paying for idle containers

Demurrage and detention are the charges importers most often call “unexpected” — and the ones that are most often avoidable. They do not depend on the ocean rate or the market. They depend on how many free days you have, and on whether the container is cleared, collected and returned within them.

Three terms, three clocks

• Demurrage — the carrier's charge for a full container staying in the port terminal after the free days. The clock starts at discharge.
• Detention — the charge for keeping the carrier's container outside the terminal (at your warehouse) too long. The clock starts when the box leaves the port and stops when the empty is returned.
• Combined free time (DnD) — one shared allowance for both. Many offers on Asia–Baltic lanes work this way.

On top of these, the terminal itself may charge storage after its own free period. It is a separate bill, so check both.

How many free days do carriers really give?

We looked at the 1,544 carrier offers with stated free time that are valid in our system today. The picture is clear:

• about 41% include 14–15 free days;
• about 41% include 21 days or more;
• about 14% — roughly one in seven — give 7 days or fewer, some as little as 3–4 days.

Two offers with the same ocean rate can therefore end up very different in total cost. Free time is part of the price — compare it at booking, not after arrival.

What actually eats your free days

• Customs holds and late documents. An original bill of lading, certificate or invoice that arrives after the ship is the most common cause.
• No truck or unloading slot. If the warehouse can only unload on Thursday, the container waits until Thursday.
• Weekends and holidays. Free days usually count calendar days, not working days.
• ETA changes. A vessel that arrives two days early starts the clock two days before you planned for it.
• Slow empty return. Detention runs until the empty container is back at the depot the carrier names.

Where tracking makes the difference

Most of these problems are timing problems. When you know where the container is and when it will actually be discharged, you can lodge the customs declaration before arrival, book the truck and the unloading slot for the right day, and plan the empty return. Live tracking of vessel ETA and container events turns demurrage from a surprise into a schedule.

A short checklist

1. Ask for free time at destination with every quote — and whether it is demurrage, detention or combined.
2. For slow-to-clear cargo, negotiate extended free time at booking. It is far cheaper than paying for it later.
3. Have all documents checked before the ship arrives. See our shipping documents guide.
4. Follow the vessel ETA and book delivery as soon as it is firm.
5. Return empties promptly to the right depot and keep the interchange receipt.

How Cargo 4S helps

Our quotes show free days next to the rate, so you compare total cost, not just freight. On the platform you follow every shipment's status and ETA, and a dedicated logistics expert flags the containers whose free time is running out — before the charge starts.