Demurrage vs Detention: Charges and Free Time

Demurrage is a charge for keeping a ship or container at a port beyond the agreed free time; detention is a charge for keeping equipment, usually a container, outside the port beyond its free time. For port agents, chandlers and repair yards, both charges are early signals of congestion and of who is under pressure to move a vessel.

The distinction matters because the two charges fall on different parties and start at different moments. A 2023 study in the Journal of Shipping and Trade notes that reduced free time and increased fees for demurrage and detention create organisational challenges across intermodal transport and raise the risk of costs for actors in the maritime supply chain (Journal of Shipping and Trade).

What is the difference between demurrage and detention?

Demurrage covers time lost at the port; detention covers time lost with the equipment after it leaves the port. In container shipping, demurrage applies when a container stays inside the terminal beyond free time, and detention applies when the container is held outside the terminal, for example at a warehouse, beyond free time.

For a bulk or tanker port call, demurrage (a charge for a ship staying at berth or waiting beyond the laytime agreed in the charter party) is the more familiar cost. It is negotiated between owner and charterer, not between the terminal and the supplier.

How does free time work?

Free time is the period allowed before demurrage or detention starts. Carriers set it in the bill of lading or tariff; ports and terminals set it in their rules. When free time shrinks, the same cargo movement produces more chargeable days.

A 2018 study in Transportation Research Part C formalised demurrage and detention as due dates and soft time windows in inland container transport, and compared how different D&D regimes affect transport efficiency (Transportation Research Part C). The practical point for a supplier is that free time is a planning variable, not a fixed fact.

Who pays demurrage and detention?

The party named in the contract pays. For container demurrage and detention, that is usually the merchant named in the bill of lading or the party that booked the transport. For ship demurrage, it is the charterer under the charter party. Port agents and suppliers are rarely the payer, but they are often the party asked to fix the delay.

• Ship demurrage is a charter-party matter between owner and charterer.
• Container demurrage is charged by the terminal or carrier to the cargo interest.
• Container detention is charged by the carrier to the party holding the equipment.

Why congestion makes D&D disputes more likely

When schedules slip, free time is consumed by waiting rather than by work. According to Drewry experts writing in Hellenic Shipping News, schedule reliability has fallen to near record lows in recent months while port congestion has built up (Hellenic Shipping News, October 2026).

The commercial consequence is a wave of invoices. According to The Loadstar, Sara Dandan, founder of FourOneOne, warns that congestion today could mean a fresh wave of disputed detention and demurrage charges tomorrow (The Loadstar, October 2026).

Congestion is not uniform. The Loadstar reported that congestion may be easing in eastern China, but Typhoon Champi threatened to disrupt vessel movements along Taiwan's north-east coast (The Loadstar, October 2026). It also reported that congestion along West Africa's coast is exposing infrastructure ill-suited to the region's container market (The Loadstar, October 2026).

What port agents and chandlers should watch

Read D&D exposure as a demand signal, not just a cost. A vessel held at anchorage waiting for a berth still needs fresh water, provisions, spares and crew support; a container held at a terminal may trigger urgent re-delivery work.

1. Track waiting time, not just ETA. A port call (the whole visit from arrival at anchorage to departure) can stretch while the published ETA stays unchanged.
2. Note which party is exposed. If the charterer is paying ship demurrage, the operations team is under pressure to shorten the stay; that is the person to call.
3. Watch free-time changes. A carrier shortening free time changes the urgency of every container move at that port.
4. Log the reason for delay. Weather, berth congestion and pilotage delays are different causes and lead to different conversations.

For a fuller work plan on congestion, see how port congestion and demurrage affect supplier work. To time outreach before the vessel berths, see why vessel arrival timing matters days before port.

How VesselReach helps

VesselReach turns vessel movements into conversations with the people who feel D&D pressure first.

• Vessel intelligence: see vessels near your ports and scheduled arrivals, which means you can call the operations team before the berth wait starts.
• Decision-maker discovery: find operations, chartering and procurement roles by vessel, which means your demurrage conversation reaches the person who owns the delay.
• Multichannel outreach: stage email, WhatsApp and phone contact, which means follow-ups happen while the vessel is still at anchorage.

Book a VesselReach demo to see how it works on your ports.