Demurrage & Detention Calculator
Work out your last free day, how many chargeable days you have run up, and what they cost under your own tariff — demurrage inside the terminal and detention outside it, calculated separately. Everything runs in your browser; nothing is uploaded.
Holidays are excluded only when you have chosen a working-days basis. Whether your free time runs on calendar or working days, and whether the first day counts, is set by your contract of carriage — not by custom. Read the booking confirmation before you rely on a figure here.
| From day | To day | Rate per day |
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Day numbers here are counted after free time expires: day 1 is your first chargeable day. Leave the last tier's "to day" empty to make it open-ended. The rates shown are placeholders — replace them with the figures on your own tariff, because they differ by carrier, port, equipment type and contract.
An estimate from the figures you entered. Your carrier's invoice governs, and terminal storage is usually billed separately.
Demurrage, detention and storage are three different charges
Importers routinely receive an invoice for one of these and argue about another. The distinction is about where the container is and who is charging you, and getting it straight is the difference between a claim you can win and one you cannot.
Charged by the carrier for the loaded container sitting in the port beyond its free time. On an import it runs from discharge until you gate the box out. On an export it runs from the moment you gate in until the vessel takes it.
Charged by the carrier for the time you keep their equipment away from the port. On an import it runs from gate-out until you hand the empty back. On an export it runs from the day you collect the empty until you gate the loaded box in.
The terminal's own charge for occupying its yard. It is a separate invoice with its own free period and its own tariff, and it accrues at the same time as demurrage. This calculator does not include it — budget for it separately.
Some carriers quote a single merged free period covering demurrage and detention together, often on a different and shorter clock than two separate allowances would give you. If your booking says something like "14 days combined", do not model it as seven plus seven. Set one leg to the combined allowance, set the other to zero, and read the result as a single pool.
What actually drives a demurrage bill
Most demurrage is caused before a truck is ever booked: an original bill of lading still in transit, a telex release not issued because an invoice is unpaid, a customs declaration held for a missing certificate. The container is sitting in the terminal because nobody can legally take it, and the clock does not care why.
Free time usually starts at discharge from the vessel, not at the arrival notice, not at customs release, and not when you were told the box was "available". Those events can be days apart, and planning from the wrong one is how importers find themselves three days into charges on the day they thought free time began.
Tariffs are tiered on purpose: the daily rate steps up the longer the box is held, and the third tier is often several times the first. A delay that looks tolerable at five days can become the largest line on the shipment by day fifteen. This is why the calculator above models tiers rather than a flat rate.
Whether free time runs on calendar days or working days is set by your contract of carriage, and it changes the answer materially over a long delay. A five-working-day allowance spanning two weekends is nine calendar days; the same five on a calendar basis is five. Check which applies before you argue an invoice.
Reefers, flat racks, open tops and tank containers typically carry less free time and higher daily rates than a standard dry box, and a reefer sitting plugged in at the terminal may attract a separate power charge as well. Do not carry a dry-box allowance across to specialised equipment.
Reducing the exposure before the ship arrives
Almost everything that works has to be done early. Negotiate free time as part of the freight rate rather than after a delay, and get the allowance written into the booking confirmation rather than agreed verbally. Have the release documents in the destination agent's hands before the vessel berths, and confirm the payment route for any collect charges, because an unpaid local charge stops a release just as effectively as a missing bill of lading. Where your cargo is likely to face inspection, plan on the inspection happening and build it into the free time you ask for, rather than treating it as an exception. And where a delay has already started, moving the container to an off-dock yard stops demurrage even though detention keeps running, which is often the cheaper of two bad options.
- Demurrage is a landed-cost line like any other: add it in the Landed Cost Estimator.
- Most demurrage starts with a document problem: Reading a Bill of Lading and the ISBP 821 Document Examination Suite.
- Who bears the cost depends on the term you agreed: the Incoterms® 2020 Navigator and FOB vs CIF vs EXW.
- Check the container number on the invoice against the box: the ISO 6346 Validator.
Frequently asked questions
Demurrage is charged while the container is still inside the terminal beyond its free time; detention is charged while you hold the container outside the terminal. Both are the carrier's charges. The terminal's own yard charge, usually called storage, is a third and separate invoice.
Normally at discharge from the vessel for imports, and at collection of the empty for export detention, but the exact trigger is set by your contract of carriage and varies between carriers and trades. It is rarely the arrival notice and rarely customs release, which is why free time is often further advanced than importers expect.
It depends on whether your allowance is expressed in calendar days or working days. Calendar-day allowances run through weekends and holidays. Working-day allowances do not, which over a long delay can be worth several days. The calculator above lets you model either basis.
Carriers do sometimes grant relief, most often where the delay was outside the merchant's control — a port strike, a customs system outage, a vessel or terminal error. Relief is discretionary unless your contract says otherwise, it is far easier to obtain while the container is still moving than after the invoice is issued, and it is granted on evidence rather than on argument. Keep the timestamps.
No, and deliberately so. Demurrage and detention tariffs differ by carrier, port, equipment type, trade lane and contract, and any published figure would be wrong for most users within weeks. You enter your own free days and tiers from your booking confirmation or the carrier's tariff page, and the calculator does the arithmetic.
Reference information for planning purposes only, and not legal advice. Free time, day-counting basis and tariff rates are set by your contract of carriage and the carrier's published tariff, which govern over any figure produced here.