Demurrage and Detention Calculator
Work out container demurrage and detention charges from discharge, gate-out and empty-return dates, free days and tiered daily rates.
Demurrage is what a shipping line charges when a full import container stays at the terminal after its free time runs out; detention is charged when you keep the line’s container outside the terminal too long before returning it empty. This calculator counts the days for each, applies the free time and up to three daily rate tiers from your carrier’s tariff, and gives the total per container and for the whole shipment.
How to use this tool
- Enter the discharge, gate-out and empty-return dates. Use expected dates to forecast the bill.
- Choose how days are counted, as set out in your carrier tariff.
- Enter the free days and the daily rate for each tier, for demurrage and for detention.
- Enter the number of containers to see the shipment total.
Formula
Chargeable days = max(0, days counted − free days); charge = tier 1 days × rate 1 + tier 2 days × rate 2 + remaining days × rate 3
With inclusive counting, days = date difference + 1, so a container discharged and collected on the same day uses one day. Demurrage runs from discharge to gate-out; detention runs from gate-out to the empty return.
Example
A container is discharged on 2 March 2026, picked up on 10 March and returned empty on 20 March, counting first and last days. At the terminal it uses 9 days; with 5 free days, 4 days are charged at $150, so demurrage is $600. Outside it uses 11 days; with 4 free days, 7 days are charged: 5 × $100 + 2 × $150 = $800 detention. The total is $1,400 per container, and the last free day at the terminal was 6 March.
Frequently asked questions
What is the difference between demurrage and detention?
Demurrage covers the time a full container occupies the terminal. Detention covers the time you use the carrier’s equipment outside the terminal. Some carriers bill both as one combined charge with a single free-time allowance.
Are weekends and holidays counted?
Charges normally run on calendar days, but some contracts count free time in working days only. This model uses calendar days only. Working-day tariffs require a separate calendar calculation and are outside its scope.
Why is the gate-out day counted twice?
With inclusive counting the gate-out day is the last day of demurrage and the first day of detention. The other option excludes the start of both periods. Neither option models every tariff: combined free time, different start triggers, working-day exclusions and blocked-terminal disputes require the actual carrier rules.
How can I keep these charges down?
Book trucking before the vessel arrives, clear customs early, negotiate extra free time in the contract, and return empties promptly. Watching the last free day is the cheapest fix.
Last updated: 2026-10-30