What is the difference between demurrage and detention?
Demurrage is charged when a full container stays at the port or terminal beyond its free time. Detention is charged when a container is kept outside the port, at your site or in transit, beyond its free time before being returned empty. Both are charged by the shipping line, usually per container per day.
Demurrage and detention are two of the most common unexpected costs on a container shipment, and two of the most avoidable. They're often confused with each other and with port storage, which is a separate charge from a different company. This guide explains the difference, shows how the costs build up and sets out how to keep them to a minimum.
The difference at a glance
| Charge | Where the container is | Clock starts | Clock stops | Charged by |
|---|---|---|---|---|
| Demurrage | In the port or terminal, still full | When free time at the terminal ends, counted from discharge | When the full container leaves the terminal | Shipping line |
| Detention | Outside the port, at your site or on the road | When free time ends, counted from when the full container leaves the terminal | When the empty is returned to the line | Shipping line |
| Port storage (quay rent) | In the terminal | When the terminal's own free storage ends | When the container is collected | Terminal operator |
On exports the same charges apply in reverse. Detention runs while the empty is with you for loading, and demurrage runs if the full container sits at the terminal waiting for a vessel.
Some carriers combine demurrage and detention into one allowance, often called merged or combined free time. In that case the clock simply runs from discharge until the empty is returned, however the days are split between the port and your site.
Free time
Free time is the number of days the shipping line gives you before charges start. It varies by carrier, port, container type and your contract. A few days each for demurrage and detention, or a combined allowance of one to two weeks, is common. Reefers and special equipment usually get less.
Free time can often be negotiated at the quote stage, especially if you ship regularly. It's much harder to get extra days once the container has landed.
How the costs build up
Most carriers charge in tiers: a lower daily rate for the first few days after free time ends, then higher rates the longer the container is held. That's why a delay of a week or two can cost far more than people expect.
- Days 1–10
- Free
- Days 11–14: 4 days at £75 per day
- £300
- Days 15–18: 4 days at £120 per day
- £480
- Charges for one container
- £780
Illustrative rates only. Every carrier publishes its own tariff, and rates for 40ft and special equipment are usually higher than for 20ft. Port storage may be charged on top if the container was also held in the terminal. Try different figures with our demurrage and detention estimator.
Multiply that by several containers held up in the same shipment and the costs can soon run into thousands of pounds, often more than the haulage itself.
Why containers get held
- Customs holds caused by missing or incorrect documents, wrong commodity codes or a selected inspection
- Unpaid freight or destination charges, so the line won't release the container
- Late haulage bookings, especially in peak season when slots are scarce
- Port congestion or bad weather delaying collection
- Slow unloading at the delivery site, or no space to receive the goods
- Empty returns delayed because the nominated depot is full or far away
How to avoid demurrage and detention
- Negotiate free time at the quote stage. If you know your site is slow to unload, ask for extra detention days up front.
- Get your documents right before the vessel arrives. Lodge the customs entry before discharge where possible.
- Pay freight and destination charges promptly, so the line releases the container without delay.
- Book haulage early, as soon as the ETA is confirmed.
- Plan unloading. If it will take a while, use a side-loader or drop and collect so the container can be emptied and returned quickly.
- Track free time for every container, not just the shipment as a whole.
Who pays?
On an import, the shipping line normally bills whoever takes delivery of the container, usually the consignee or their forwarder. Your Incoterms and the contract with your supplier decide whether any of it can be recharged. If a charge was caused by a carrier's own delay, such as a terminal problem or a late release, it's worth disputing with evidence of the dates.
How we can help
We agree free time when we quote, check documents before arrival, book haulage early through our sister company, and track each container's free time so you hear about a risk before it becomes a charge. See also what to check before your container lands.
Written by the 365 Freight team · Last reviewed . General guidance only, so check the specifics for your shipment.