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Detention & Demurrage
Free time on a container is a courtesy window, not an unlimited one — once it runs out, the carrier or terminal starts billing by the day. This calculator applies a flat daily rate to the days you go over free time so you can estimate the charges before they show up on an invoice.
Estimated charges
$1050.00
7 chargeable days after free time
Results are indicative only. Rates, transit times, classifications, and charges vary by carrier, lane, and contract. For binding quotes, post a request on CargoLinked or contact your forwarder.
How it works
Every shipment gets a block of free time — days the container can sit at the terminal or with the consignee before per-diem charges kick in. Once the days used exceed that free allowance, every additional day is billed at the daily rate, so the total charge is simply the number of days over free time multiplied by that rate.
This calculator uses a single flat rate for simplicity. Many real-world tariffs actually escalate the rate the longer a container stays out — for example, a lower rate for the first few chargeable days and a higher rate after that — so treat the flat-rate figure here as a baseline estimate and confirm the exact schedule in your carrier or terminal's tariff before assuming the total won't grow faster the longer a container is held.
Chargeable days = max(0, Days used − Free days) Total = Chargeable days × Daily rate
Worked example
5 free days, 12 days used, $150/day rate
- Chargeable daysmax(0, 12 − 5) = 7 days
- Total charges7 × $150 = $1,050
Estimated charges: $1,050 (7 chargeable days)
Frequently asked questions
What's the difference between demurrage and detention?
The mainstream convention is that demurrage applies while the container is still inside the port or terminal past its free time, and detention applies once the container has left the terminal — with the consignee or at their facility — and is being held past its own free time before being returned empty. Some carriers merge the two into a single combined per-diem charge, so always check whether your carrier's tariff draws that line or treats it as one continuous charge.
How many free days do I typically get?
Free time commonly runs 3-7 days, but it varies significantly by carrier, port, and what was negotiated in your contract — some trade lanes or high-volume shippers negotiate longer windows. There is no universal default, so confirm the exact free-time allowance on your booking confirmation or service contract rather than assuming a standard figure.
How can I avoid detention and demurrage charges?
Arrange pickup, customs clearance, and empty-container return well before free time expires, and flag potential delays (customs holds, missing documents, congested delivery slots) to your forwarder as early as possible so they can request an extension or expedite the release. Booking trucking and warehouse space in advance, rather than after the container has already arrived, is usually what makes the difference between staying inside free time and going over it.
Who actually bills detention and demurrage charges?
The ocean carrier or the terminal operator issues the charge, but it is typically invoiced to whoever is named on the bill of lading or booking — often the forwarder, who may then pass it through to the shipper or consignee depending on the contract. Check your service agreement or freight quote to see who is responsible for per-diem charges before they accrue.
Do detention and demurrage rates increase the longer a container is held?
Often, yes — many tariffs use a tiered schedule where the daily rate rises after an initial block of chargeable days, rather than staying flat for the whole overage. This calculator estimates using one flat rate for simplicity, so if your carrier or terminal uses a tiered schedule, run the higher later-tier rate against the days it actually applies to for a more accurate total.
Related tools
Estimates & assumptions
- Free-time allowances and daily rates vary by carrier, port, and contract — the figures here are planning estimates, not a quoted tariff.
- This calculator applies one flat daily rate; some carriers use a tiered/escalating schedule instead, which can produce a higher total than a flat-rate estimate.
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