Few things frustrate importers more than opening an invoice full of charges they didn’t expect. Demurrage, detention, and per diem are the three fees most likely to appear, and because the terms are often used interchangeably, many shippers don’t realize they’re being billed for three different things. Here’s a plain-English breakdown of each fee, who charges it, and the practical steps that keep all three off your invoice.

The three fees at a glance

All three charges relate to time — either your container sitting somewhere too long, or equipment staying in your custody too long. The difference comes down to where the container is and whose equipment clock is running.

• Demurrage is charged by the terminal (or the ocean carrier on the terminal’s behalf) when a loaded import container stays at the port beyond its allotted free time.
• Detention is charged by the ocean carrier when you keep their container outside the terminal — at your warehouse or yard — beyond the free days allowed for unloading and returning it.
• Per diem is, in most U.S. trades, another name for detention: a daily charge for keeping the carrier’s container or chassis past the free period. Some carriers use per diem for equipment and detention for driver waiting time, so always check the tariff language.

Demurrage: the port clock

When your vessel discharges at PortMiami or Port Everglades, the terminal grants a set number of free days — often four to five working days — to pick up the container. Miss that window and demurrage starts accruing daily, frequently on an escalating scale that can climb past $200–$300 per day within a week.

What triggers it

Late customs clearance, missed appointments, terminal congestion, or simply not having a drayage carrier booked in time. The clock doesn’t pause for weekends at many terminals, and it rarely pauses for problems that aren’t the terminal’s fault.

How to avoid it

Track your vessel’s actual arrival, clear customs before discharge whenever possible, and have your container drayage carrier dispatched against the Last Free Day — not the day after. If the port is congested, a pre-pull to a nearby yard is almost always cheaper than a week of demurrage.

Detention and per diem: the equipment clock

Once the container leaves the terminal, a second clock starts. The ocean carrier typically allows a handful of free days to strip the container and return it empty. Keep it longer and detention (per diem) accrues — commonly $100–$200 per day, per container.

What triggers it

Slow unloading at the warehouse, chassis shortages, empty-return restrictions at the terminal, or simple scheduling gaps. A closed return depot can burn free days through no fault of yours, which is why documenting return attempts matters if you ever dispute a charge.

How to avoid it

Schedule unloading before the container arrives, consider transloading the cargo at a container freight station so the box can be returned immediately, and work with a carrier that monitors empty-return openings daily.

Where a local drayage partner changes the math

An asset-based drayage provider with its own yard gives you a buffer between both clocks. Go Drayage’s five-acre secured yard near PortMiami can hold more than 450 containers, which means a box can come off the port clock the moment it’s pulled and sit in yard storage until your warehouse is ready — usually at a fraction of what demurrage or detention would cost. Company-owned trucks and chassis also remove the equipment-availability excuses that so often burn free days in South Florida.

Quick comparison

• Demurrage — billed by terminal/carrier; container inside the port; avoided by fast pickup and pre-pulls.
• Detention/per diem — billed by ocean carrier; container outside the port; avoided by fast unloading, transloading, and prompt empty returns.

Frequently asked questions

Can demurrage and detention both apply to the same container?

Yes. A container can accrue demurrage while waiting at the terminal, then accrue detention if it’s returned late after pickup. Managing each clock separately is the only way to avoid paying twice.

Are these fees negotiable?

Sometimes. Free time can be negotiated into ocean contracts, and charges caused by terminal closures or return restrictions can often be disputed with documentation. Your drayage carrier’s gate receipts and return attempts are key evidence.

How much free time do I get at PortMiami?

It varies by terminal and carrier agreement, but four to five working days is typical for import demurrage. Confirm your specific allowance on every shipment rather than assuming — free time is set by tariff, not by habit.

Ready to keep your containers off both clocks? Get an instant drayage quote or call (786) 445-0150.