Demurrage is the fee when a container sits in the port past its free time. Detention is the fee when you keep the container outside the port past its free time. Both usually go to the shipping line, both grow daily, and both are avoidable with fast customs clearance, early trucking, and prompt empty return.
What is demurrage?
Demurrage is the fee charged when a container stays inside the port or terminal beyond its free time. On an import, the clock starts when the container is discharged from the vessel and stops when it leaves the terminal. It is charged per container, per day.
Many shipping lines count calendar days, so weekends and holidays use up free time. A vessel that arrives on a Thursday can lose days to the weekend before customs even clears. On exports, demurrage can also apply when a loaded container is returned to the port but can’t be shipped out in time.
What is detention?
Detention, also called per diem, is the fee charged when you keep a shipping line’s container outside the terminal beyond its free time. On an import, the clock starts when the container leaves the terminal (gate out) and stops when you return the empty container to the depot.
It pays for the line’s equipment, which it can’t reuse while you hold it. Typical causes are slow unloading at your warehouse, or an empty that isn’t returned on time.
What is the difference between demurrage and detention?
The difference is where the container is when the delay happens. Demurrage happens inside the terminal, and detention happens outside it.
| Factor | Demurrage | Detention |
|---|---|---|
| Where the container is | Inside the port or terminal | Outside the terminal, such as your warehouse or yard |
| Usually billed by | The shipping line (terminals may add storage) | The shipping line |
| Clock starts | When the container is discharged from the vessel | When the container gates out of the terminal |
| Clock stops | When the container leaves the terminal | When the empty container is returned to the depot |
| Typical free time | Commonly 3 to 7 days, varies by line and port | Commonly 3 to 10 days, varies by line and contract |
| Main fix | Faster customs clearance and pickup | Faster unloading and empty return |
Terminals can also charge their own storage after their free days, so ask your forwarder to list every charge and who is billing it. Some lines also offer combined free time, where one set of days covers both charges. Confirm this at the quote stage.
How are demurrage and detention charges calculated?
They are charged per container per day once free time ends, and the daily rate usually rises in tiers the longer the container stays. That means ten days late costs much more than ten times the first day’s rate.
Here is an example with illustrative numbers, not Postkodes rates. Your demurrage free time is 5 days. Days 6 to 8 cost 100 per day, and days 9 to 12 cost 200 per day. You collect the container on day 12:
3 days at 100 is 300. 4 days at 200 is 800. Demurrage is 1,100.
Then your detention clock starts when the container leaves the terminal. With 7 free days and an empty returned 3 days late at 80 per day, detention adds 240. The total for one container is 1,340, and nothing in that bill is freight.
What is free time and how long is it?
Free time is the number of days you can hold a container before charges begin. It is set by the shipping line, the port and your contract, and the last free day is the final day before charges start.
Industry guides commonly put demurrage free time at 3 to 7 days and detention free time at roughly 3 to 10 days, but the range is wide. Confirm the exact free days on your quote or bill of lading, ask whether weekends count, and get both figures in writing.
Air freight has no container, so the equivalent is airport storage, and free time is usually much shorter, often 1 to 3 days, according to industry guidance. Confirm the current terms with Postkodes.
What causes demurrage and detention?
Almost always a delay somewhere between the vessel and your door. The usual causes are:
- Customs holds from missing, late or incorrect documents
- Physical inspections or other agency checks
- Port congestion or a full terminal yard
- Trucking not booked in advance
- A warehouse that is full, closed or has no delivery appointment
- Disputes between the shipper and the consignee
- Slow unloading, or an empty depot that is closed or full
How do you avoid demurrage?
Plan the pickup before the vessel arrives, not after.
- Ask your forwarder for the last free day in writing, before the vessel arrives.
- Get your documents ready early: the bill of lading, commercial invoice and packing list. Our guide to commercial invoices and packing lists shows what each should contain.
- Pre-clear the cargo where your customs system allows it, so it can be released as soon as it lands.
- Book trucking before the vessel arrives, not after customs clears.
- Confirm that your warehouse has space and a delivery appointment.
- Track the vessel and container, and act on any delay the same day.
- If you ship regularly, ask for longer free time. Lines often grant it to steady volume.
How do you avoid detention?
Move the container through your premises quickly, and return the empty.
- Have staff and equipment ready before the container arrives.
- Unload as soon as it lands, and return the empty immediately.
- Check the depot’s opening hours and return location in advance, so you don’t miss the window.
- Ask for extra free time if your cargo needs a long unload.
- If a customs inspection holds the container, ask the line for an extension.
- Keep your return receipt as proof of the date.
What can you do if you have already been charged?
Check the invoice against your bill of lading first: the free days, the daily rate and the start date. Collect evidence of delays that weren’t your fault, such as customs hold notices, terminal closures or strikes. Then ask the shipping line, through your forwarder, for a waiver or an extension.
Lines have dispute processes, and a well-documented case can win a partial or full waiver. Raise it quickly, because the charges keep growing every day.
What about demurrage and detention at Lagos and other West African ports?
The charges hurt most where clearance is slow. In August 2026, a Nigerian trade body linked rising demurrage and detention at Apapa and Tin Can Island to port congestion and containers not being returned on time. An earlier study by the Nigerian Shippers’ Council, reported by BusinessDay, found containers dwelling about 21 days at Nigerian ports against five demurrage-free days.
Terms change, so confirm the current free days with Postkodes. My advice: if you’re shipping to Nigeria, have your clearance documents ready before the vessel arrives, and never assume the free days will cover the time clearance takes.
Frequently asked questions
What is the difference between demurrage and detention?
Demurrage is charged when a container stays inside the port or terminal past its free time. Detention is charged when you keep the container outside the terminal past its free time. The difference is where the container is when the delay happens.
Who charges demurrage and detention?
In most cases the shipping line bills both, using its published tariff or your contract. Terminals can also charge separate storage after their own free days, so ask your forwarder to list every charge and who is billing it.
How many free days do I get?
Commonly 3 to 7 days for demurrage and about 3 to 10 days for detention, according to industry guides, but it varies by shipping line, port and contract. Check the free days on your quote or bill of lading, and ask whether weekends count.
Can demurrage and detention be waived?
Sometimes. Shipping lines have dispute and waiver processes, and a well-documented case, such as a customs hold or terminal closure that wasn’t your fault, can win a partial or full waiver. Raise it quickly, because charges grow daily.
Do demurrage and detention apply to LCL or air freight?
Not in the same way. LCL cargo shares a container, so you’re more likely to face storage charges at the warehouse where it is unpacked. Air freight has no container, so airport storage applies, usually with much shorter free time. Ask your forwarder what applies.
Does the clock run on weekends and holidays?
Often yes. Many shipping lines count calendar days, so weekends and holidays use up free time. A vessel arriving on a Thursday can lose days to the weekend before customs clears, so check how your line counts days.
What should you do next?
Before you book, ask for the free days at the destination in writing, for both demurrage and detention, and plan your clearance and trucking before the vessel arrives.
When you request a quote through Postkodes’ Quick Quote page, ask what free time applies and who bills the charges. You can also look at our sea freight services to see how container shipments are handled.
