Demurrage & Detention Calculator

Demurrage and Detention (D&D) are charges applied to shipping containers that have exceeded the free time allocated by the carrier. Understanding these fees is crucial for keeping logistics costs down and avoiding supply chain bottlenecks.

Demurrage charges are levied when a full container sits at the port or terminal facility beyond the allowed free days. It is charged per day and often operates on an escalating tier system, meaning the price increases the longer the container stays at the port.

Detention refers to the charge applied when a consignee holds onto the carrier's empty container outside the port (e.g., at the warehouse), failing to return it to the designated carrier depot within the permitted free time.

Storage charges are collected by the port, terminal, or rail facility for the physical space a container occupies. While distinct from Demurrage (which is charged by the carrier for using the container equipment), storage fees often accumulate over the exact same period.

Demurrage applies to a full container that stays inside the port or terminal beyond the free time, while detention applies to a container the merchant has taken out of the terminal and held too long before returning the empty equipment. In short, demurrage is the in-terminal clock and detention is the out-of-terminal clock, and both are billed by the carrier per container per day.

Free time is the number of days a carrier or terminal allows you to use a container or occupy terminal space at no extra cost before demurrage, detention, or storage charges begin. It typically ranges from 3 to 7 days depending on the carrier, the port, and your contract, and it is often the single biggest factor in whether you incur D&D charges.

The per-diem rate is the daily charge for each chargeable day past the free time, multiplied by the number of containers and the number of days held. Most carriers use an escalating tier structure, so the first few chargeable days carry a lower rate and the rate rises steeply the longer the container remains, which is why the calculator above lets you model each tier separately.

The most effective steps are arranging customs clearance and trucking before the vessel arrives, pre-paying duties, and booking equipment return slots early so containers move within the free time. Tracking milestone dates in real time, requesting extended free time during contract negotiation, and monitoring port congestion all help you act before the per-diem clock starts running.

Demurrage is billed by the carrier to whoever is named as responsible on the bill of lading, which is usually the consignee or importer receiving the cargo. Under certain Incoterms or forwarder agreements the cost can fall to the shipper instead, so it is worth confirming who carries the demurrage risk before the container arrives.