1. The shipment
2. Demurrage tariff (port or terminal side)
3. Detention tariff (empty not yet returned)
Result
Questions people ask
What is the difference between demurrage and detention?
Demurrage is the charge for a loaded container sitting at the port or terminal past its free time. Detention is the charge for keeping the container outside the terminal past its free time, until the empty is returned. They run on separate clocks with separate free days and rates, and a delay at one end can be billed at both.
What is the last free day, and why does it matter so much?
It is the final day the container can leave the terminal without a demurrage charge. Charges are tiered, so each day after it is billed at a rising rate, and the last days cost the most. The calculator shows the last free day for both clocks and what one more day costs.
Do weekends and holidays count toward free time?
It depends on the carrier and the port. Some count every calendar day, some skip weekends and holidays. The calculator lets you set that for each clock, and lets you add exemption days for a closed terminal or a hold that was not your doing. Check your own tariff for the rule that applies.
How much is paying to pick up a container earlier worth?
The calculator moves pickup and the empty return earlier together, so detention keeps its length and only the port-side clock changes. The saving per container is the most a rush fee, an earlier trucker slot or expedited drayage is worth paying.
Is this legal or customs advice?
No. It is arithmetic on the dates and tariff numbers you type in. The defaults are placeholders, not any carrier's tariff. Whether a charge was billed correctly or can be disputed is for you and your advisor to decide.
Not decided
Your carrier's actual tariff, free days and rates, how your carrier counts the first and last day (this counts the day after discharge or gate-out as day 1), holidays, whether a charge was validly billed or can be disputed, regulatory billing and dispute windows, chassis and pre-pull per-diem, storage at a container freight station, and currency. Every default is a placeholder, not a rate card: check each one against your own tariff.
Related tools: the import landed cost calculator (duty, tariffs and fees on the same shipment) and the container load planner.