QUICK ANSWER Demurrage is charged when a loaded container stays inside the port terminal past its free time, typically 4 to 5 free days at US ports. Detention, often billed as per-diem, is charged when the container or chassis stays outside the terminal past its free time, usually because the empty has not been returned. Both run daily and escalate, commonly from around $150 a day into the $300s.
Demurrage is the charge importers meet the hard way: the vessel arrived, something stalled, and now a container is earning the terminal money by the day. Detention is its twin on the other side of the gate. This guide separates the two, adds the per-diem, storage, and driver-detention variants that get mixed into the same conversation, and shows what actually stops each clock.
One principle behind all three charges
Every charge in this family prices the same thing: your cargo is occupying someone else's asset longer than agreed. The terminal's ground space, the carrier's container, the chassis under it on the drayage leg, the driver's hours. Each asset owner grants a window of free time, and past it, a daily meter runs. The names differ by which asset is waiting and which side of the terminal gate it is on, and that distinction decides who bills you and what stops the meter.
Demurrage: the terminal clock
Demurrage applies to a loaded import container sitting inside the terminal after discharge from the vessel. US ports typically allow 4 to 5 working days of free time; after that, the terminal or carrier bills the consignee daily, and the rate climbs in tiers the longer the box sits. Each terminal publishes its own tariff; the numbers differ port to port, the tiered shape does not.
Typical US port demurrage escalation (illustrative)
| Days past free time | Daily rate |
|---|---|
| Days 1 to 4 | $150 to $250 |
| Days 5 to 8 | $250 to $350 |
| Day 9 onward | $350 or more |
The usual causes are a customs hold or exam, missing paperwork, a delivery order that is not ready, or simply no trucker booked when the container discharged. The charge stops only when the container physically leaves the terminal, which is why release without pickup solves nothing.
Detention and per-diem: the equipment clock
Detention, which US truckers and carriers often call per-diem, starts once the container is out of the terminal. The carrier's equipment free time, commonly 3 to 5 days, covers delivery, unloading, and returning the empty. Keep the container or chassis longer, because unloading queued behind a full warehouse or the empty-return appointment was not available, and the daily rate runs until the equipment is back. Rates commonly sit between $100 and $200 per day per container, with chassis rental accruing separately.
Where the two clocks trade places
The gate is the border between the two charges.
Demurrage vs detention
| Demurrage | Detention (per-diem) | |
|---|---|---|
| Where the container is | Inside the terminal | Outside the terminal |
| What is being occupied | Terminal ground space | The carrier's container and chassis |
| Free time, typical | 4 to 5 working days | 3 to 5 days |
| Clock stops when | The container exits the gate | The empty equipment is returned |
| Usual cause | Hold, paperwork, no trucker booked | Slow unloading, no return appointment |
Demurrage, storage, or something else on the invoice
Two more lines get mistaken for demurrage, and the difference decides whom you dispute with. Storage is the terminal's own charge for the ground the container occupies, billed under the terminal's tariff; at some ports it runs in parallel with carrier demurrage on the same box, which is how one container produces two space-related bills. And for LCL cargo there is CFS storage, charged by the warehouse when deconsolidated freight is not collected within its free days.
The space-and-time charges, and who bills them
| Charge | Billed by | For what |
|---|---|---|
| Demurrage | Carrier (or terminal, port by port) | Loaded container inside the terminal past free time |
| Terminal storage | The terminal, own tariff | Ground space, can run alongside demurrage |
| Detention / per-diem | Carrier | Equipment kept outside the terminal past free time |
| Chassis rental | Chassis pool or trucker | The chassis, per day, separate meter |
| CFS storage | The CFS warehouse | LCL cargo not collected within free days |
When a bill arrives, the first question is not "how much" but "who is charging, for which asset, over which dates". Overlaps and double-counting happen, and they are exactly what the billing rule below exists to expose.
Driver detention: the same word at the dock
Trucking uses detention for a third, unrelated meter: a driver waiting at your warehouse beyond the free window, usually one to two hours, bills hourly, commonly $50 to $100 per hour. It is a trucking accessorial, not a container charge, but it lands on the same freight invoice, so importers meet all three under the same confusing name. A dock crew that turns containers in under an hour makes this one disappear entirely.
The FMC billing rule importers should know
Since May 2024, the Federal Maritime Commission's demurrage and detention billing rule (46 CFR Part 541) sets conditions on how these charges are invoiced: the bill can go only to the party that contracted for the transport or to the consignee, and to no one else (not the trucker, not an agent who never contracted the move), it must be issued within 30 calendar days of when the charge stopped accruing, and it must include the information needed to identify and dispute the charge, with a stated dispute process.
TAKEAWAY An invoice that fails the FMC rule's requirements is not properly payable as issued. Check every demurrage and per-diem bill against three questions: am I the contracted party or the consignee, did it arrive within 30 days, and does it show the dates, container, and dispute path. Billing errors in this charge family are common enough that the check pays for itself.
Stopping the clocks in practice
Each meter has one off switch. Demurrage stops with a pickup, so the entry should be filed before arrival, the delivery order ready at discharge, and the trucker dispatched against the release rather than booked after it. Detention stops with the empty return, so the unloading slot and the return appointment get planned when the delivery is scheduled, not after the warehouse gets around to the box. Importers with steady volume have one more move: extended free time negotiated into carrier contracts, usually worth more than the small rate discount it replaces. None of this is sophisticated; all of it has to happen before the vessel arrives to work.
TAKEAWAY The tiers make time expensive fast. A container that clears free time and then waits six more days at escalating rates collects roughly $1,400 in demurrage alone; if the empty then goes back four days late, per-diem adds $400 to $800 on top. Two ordinary delays, one at the terminal and one at the warehouse, and the surcharge bill rivals the ocean freight.
How Platton keeps the charges off your invoice
Demurrage and detention are lost races against known deadlines, so Platton runs the race before it starts.
Entry filed before the vessel docks
Customs clearance The broker begins the clearance process in advance within the available time frame, and the free-time window opens with a container that is already cleared.
Trucker dispatched against the release
Drayage is booked to the discharge schedule, so the box exits the gate inside free time instead of joining the pickup queue afterward.
Empty return planned with the delivery
The unloading slot and return appointment are set when delivery is scheduled, which is what keeps per-diem and chassis days at zero.
Every free-time clock visible
Discharge, last free day, and return deadline are tracked per container in real-time tracking, so a slipping date is chased days before it becomes a tiered daily charge.
Get an import quote with free time managed for you
Common Questions About Demurrage and Detention
What is the main difference between demurrage and detention?
Location. Demurrage bills a loaded container sitting inside the terminal past its free time; detention, or per-diem, bills the carrier's equipment kept outside the terminal past its free time, usually because the empty has not been returned. Demurrage ends when the container exits the gate, detention when the equipment comes back. A single shipment can run up both if it stalls twice.
Who pays demurrage and detention charges?
The importer of record or consignee, in practice. The terminal and carrier bill the party responsible for the container under the transport contract, and under the FMC's billing rule the invoice can go only to the contracting party or the consignee. Even when a forwarder or trucker receives the bill first, the cost flows through to the importer unless someone else's error caused the delay.
How much is demurrage per day?
At US ports, commonly $150 to $250 per day in the first tier past free time, rising through tiers to $350 or more as the days accumulate. Detention typically runs $100 to $200 per day plus chassis fees. Exact figures vary by port, terminal, and carrier tariff, but the structure is universal: the rate climbs the longer the asset waits, so early days are the cheap ones.
How many free days do you get before demurrage?
Typically 4 to 5 working days at US terminals from container discharge, though the exact allowance depends on the port and the carrier contract. Equipment free time for detention usually runs 3 to 5 days from gate-out. Larger importers sometimes negotiate extended free time into their carrier contracts, which is often worth more than a small rate discount on lanes with slow inland legs.
What is the FMC rule on demurrage and detention billing?
The Federal Maritime Commission rule, in force since May 2024, requires that demurrage and detention invoices go only to the contracting party or the consignee, be issued within 30 days of when the charge stopped accruing, and contain the details needed to verify and dispute the charge through a stated process. Invoices that do not meet the requirements are not properly payable, which makes checking every bill against the rule worthwhile.
Related Ocean Freight Guides
Ocean freight knowledge hub: the full ocean shipping guide index.
Ocean freight rates and surcharges: the rest of the charge stack around the base rate.
Ocean transit times, China to US: planning the arrival the free-time clock starts from.
