Demurrage and detention explained
Short answer
Both charges are about time, but on opposite sides of the terminal gate. Demurrage is charged when your container sits inside the port or terminal past its allotted free time. Detention is charged when you keep the container outside the terminal — at your warehouse, for example — longer than allowed before returning the empty. You avoid both by collecting your cargo and returning the equipment before the free time runs out.
Demurrage vs. detention
The distinction comes down to where the container is when the clock is running:
Where | What it's for | |
|---|---|---|
Inside the port / terminal | The container stays in the yard past its free time before you pick it up | |
Outside the terminal | You hold the container (e.g. at your warehouse) too long before returning the empty |
Both are billed per container, per day, and the daily rate often steps up the longer the container is held.
How free time works
Carriers and terminals allow a set number of free days for pickup and for returning equipment. Free time starts once the container is available, not the moment the vessel arrives.
A container is not ready the same day the ship docks. Because a large vessel can carry more than 10,000 containers, unloading typically takes a few business days. After unloading:
A full container load (FCL) is placed in the container yard (CY) and becomes available for pickup there.
A less-than-container load (LCL) is moved to a container freight station (CFS) and deconsolidated before it can be picked up.
To avoid demurrage, collect your cargo from the CY or CFS before the Last Free Day — the deadline after which demurrage begins.
How charges accrue
Demurrage accrues for each day the container remains in the terminal past the Last Free Day, until you collect it.
Detention accrues for each day past your allowed free time to return the empty container after you've taken it away.
Rates are set by the carrier and terminal, are charged per container, and commonly escalate over successive days — so a short delay is far cheaper to fix than a long one.
How to avoid them
Have paperwork and customs ready before arrival so nothing blocks release. A customs hold can eat your free time while the clock keeps running.
Arrange trucking early so a driver is available as soon as the container is free.
Return empties promptly to stop detention.
Watch port congestion on your lane — a backed-up port makes pickup slots scarce and free time tighter.
Track your shipment so you know the Last Free Day in advance. See Track your shipments.
How this works at Prime Freight
We track your containers toward arrival and work to line up customs clearance and trucking so your cargo moves before the free time expires. Demurrage and detention information for your containerized shipments appears in the portal — see Track your shipments — and if a delay threatens the Last Free Day, contact your Prime Freight team so we can push to get the container moving.