Q: What does this tool do?
The Demurrage, Detention & Storage Calculation Tool computes the extra charges incurred when containers exceed the permitted free time in maritime shipping. It supports tiered tariff structures, calculates costs for multiple containers at once, and presents results with a detailed breakdown table and a daily cost bar chart.
Q: What is the difference between Demurrage, Detention, and Storage?
Demurrage is the charge applied when a container stays within the port or terminal boundaries beyond the allowed free time. It is calculated from the discharge date to the gate-out date. Detention is the charge applied when a container is used outside the port (after delivery) beyond the allowed free time. It is calculated from the gate-out date to the empty return (gate-in) date. Storage is the charge for storing cargo at the port or terminal yard. It is calculated from the discharge date to the cargo pickup date.
Q: What does the "Combined D&D" option do?
Combined D&D calculates both demurrage and detention simultaneously. You can enter separate free days and tiered tariffs for each. Results are displayed individually and as a grand total.
Q: Does the tool work offline?
Yes. It is entirely HTML and JavaScript-based with no server dependency. You can open the file in any browser and use it without an internet connection.
Q: Which container types are supported?
The tool supports the following container types: 20' DC and 40' DC (dry cargo), 40' HC (high cube), 20' RF and 40' RF (reefer), 20' OT and 40' OT (open top), 20' FR and 40' FR (flat rack), and 20' Tank.
Q: Does the Import/Export selection affect the calculation?
The direction is used for labeling in the results. It does not directly change the calculation formula, but it serves as a reminder that carriers typically apply different tariffs for import and export.
Q: How do I calculate costs for multiple containers?
Enter the quantity in the "Container Count" field. The tool calculates the unit cost and then multiplies it by the container count to show the grand total. All containers are calculated with the same tariff and free day conditions.
Q: Which currencies are supported?
USD ($), EUR (€), TRY (₺), and GBP (£) are supported.
Q: Is the Carrier/Line field mandatory?
No, it is optional. When filled in, it appears as a tag on the results screen. It does not affect the calculation — it is provided for reporting convenience only.
Q: Which dates need to be entered?
This depends on the calculation type. Demurrage and Storage require the discharge date and the gate-out date (or cargo pickup date). Detention requires the gate-out date and the empty return (gate-in) date. Combined D&D requires all three dates: discharge, gate-out, and empty return.
Q: What is the date format?
Dates are entered in DD/MM/YYYY format (e.g., 15/03/2026). The tool automatically inserts "/" separators as you type.
Q: How is the total number of days calculated?
Demurrage days = the number of calendar days between the discharge date and the gate-out date. Detention days = the number of calendar days between the gate-out date and the empty return date. Day counts are updated automatically as dates are entered.
Q: What are "free days"?
Free days are the period during which the carrier does not charge any fees. For example, if 7 free days are granted, the first 7 days are free of charge. Chargeable days = total days − free days.
Q: How does the tiered tariff system work?
The chargeable days after the free period can be divided into tiers. For example: days 8–14 at $50/day, days 15–21 at $100/day, day 22 onward at $150/day. Carriers typically apply escalating rates as the duration increases.
Q: How do I add a tier?
Click the "Add Tier" button to create a new tier. For each tier, enter the start day, end day, and daily rate. The tool automatically splits the last existing tier in half to create the new one.
Q: Can I delete a tier?
Yes. Click the "×" button on any tier to remove it. At least one tier must remain. When a tier is deleted, the neighboring tier's range is automatically extended to cover the gap.
Q: Are tariffs entered separately in Combined D&D?
Yes. Separate free day counts and separate tiered tariffs are entered for demurrage and detention. The demurrage tariff section appears at the top, and the detention tariff section appears below it.
Q: What is shown on the results screen?
The top section displays summary statistics: total days, free days, chargeable days, unit cost (if multiple containers), and total cost. The middle section shows a daily cost bar chart. The bottom section contains a detailed breakdown table listing the free days, the number of days in each tier, the daily rate, and the tier cost.
Q: How do I read the daily cost chart?
Each bar represents one day. Short bars represent free days (no charge). The height of colored bars is proportional to that day's rate. Hovering over a bar shows the rate information for that day.
Q: What happens if there are no chargeable days?
If the container was processed within the free period, the tool shows a total cost of zero and displays a green info box stating "No additional charges apply."
Q: Are demurrage and detention shown separately in Combined D&D results?
Yes. The detailed breakdown table lists demurrage and detention under separate section headers. Each section has its own subtotal. If multiple containers are selected, the grand total appears at the bottom.
Q: Are the results from this tool definitive?
No. This tool is for informational purposes only. Actual charges may vary depending on the carrier, terminal, and contract terms. For definitive amounts, the carrier's current tariff schedule and contractual provisions should be consulted.
