About this calculator
Audit a terminal demurrage date clock using documented boundary events, free days and daily rate tiers. Free-time consumption and billed-day calendars are separately selected agreement terms.
Inputs
How to use this calculator
Clock and agreement inputs
- Terminal clock anchor dateThe governing notice/agreement determines the event that starts the clock; not necessarily discharge or availability.
- Terminal clock ending dateEnter the actual applicable ending event in the terminal’s local calendar.
- Count anchor date in this clock?Use your agreement’s starting-day boundary; no default legal rule is implied.
- Count ending date in this clock?This is an explicit agreement choice.
- Free daysCounted on the free-time calendar below. This is an example, not a carrier allowance.
- Calendar for consuming free daysFree-time exclusions can differ from billable-day exclusions.
- Dates excluded from free-time countingOptional comma-separated YYYY-MM-DD dates. Used only when the selected calendar includes entered exclusions. No holiday schedule is supplied.
- Calendar for billed days after free timeA non-billable date may still advance an elapsed-day rate tier.
- Dates excluded from billingOptional comma-separated dates. Used only by an exclusion-enabled calendar. Record terminal closures/holidays only when your agreement permits them.
- How escalating rate-tier days advanceTier start 1 is the first post-free-time day under the selected basis; this is not the day since discharge.
- Identical containers on this same clockSame events, calendars, free time and rates for each. Calculate differing containers separately.
Shared rate tiers
- Rate tier start dayUse unique positive whole days; the table must include day 1.
- Daily rate (USD/container)Enter the applicable agreement rate for each tier.
Enter the shipment or scenario values, then select Calculate result.
Method
Formula and variables
Walk the explicitly included local calendar dates. Consume free days only on the free-time calendar until exhausted. After that period, charge eligible dates using a separate billable-day calendar. Choose each rate by its start day under charged-day or elapsed-post-free-time progression. Sum daily charges × identical containers.
- Terminal clock anchor date
- The governing notice/agreement determines the event that starts the clock; not necessarily discharge or availability.
- Terminal clock ending date
- Enter the actual applicable ending event in the terminal’s local calendar.
- Count anchor date in this clock?
- Use your agreement’s starting-day boundary; no default legal rule is implied.
- Count ending date in this clock?
- This is an explicit agreement choice.
- Free days
- Counted on the free-time calendar below. This is an example, not a carrier allowance.
- Calendar for consuming free days
- Free-time exclusions can differ from billable-day exclusions.
- Dates excluded from free-time counting
- Optional comma-separated YYYY-MM-DD dates. Used only when the selected calendar includes entered exclusions. No holiday schedule is supplied.
- Calendar for billed days after free time
- A non-billable date may still advance an elapsed-day rate tier.
- Dates excluded from billing
- Optional comma-separated dates. Used only by an exclusion-enabled calendar. Record terminal closures/holidays only when your agreement permits them.
- How escalating rate-tier days advance
- Tier start 1 is the first post-free-time day under the selected basis; this is not the day since discharge.
- Identical containers on this same clock
- Same events, calendars, free time and rates for each. Calculate differing containers separately.
- Rate tier start day
- Use unique positive whole days; the table must include day 1.
- Daily rate (USD/container)
- Enter the applicable agreement rate for each tier.
Interpret the result
The result is an entered-terms charge estimate for identical containers on the same clock. It does not determine legal entitlement, invoice compliance or the event that should govern the agreement.
Outputs: Free days, billable days and estimated terminal charges
Terminal demurrage only, under entered terms. No automatic port/carrier calendars, combined detention/demurrage, per-hour cutoffs, rolling 24-hour clocks, legal entitlement, availability evidence, dispute outcome or invoice compliance is determined. Weekday mode means Monday–Friday; enter any allowed holidays separately. Rate tiers start at post-free-time day 1. Full period is limited to 3,660 days. The calendar is date-only in the governing terminal locale; browser time zone is not used.
Worked example
Check the arithmetic
This example uses the starting values shown above. The arithmetic below is calculated independently of the interactive result.
Work through the calculation
- November 2–12, 2026 inclusive contains 11 calendar dates.
- Three included free dates are November 2–4; billed dates are November 5–12, giving 8 days.
- Default single-tier charge = 8 × $100 × 1 container = $800.
Compare the displayed result
Expected displayed result: $800.00
FAQs
Do excluded billing dates also stop free time?
Only if the free-time calendar excludes them too. The tool keeps the two calendars separate, and tier progress can follow billable or elapsed days as entered.
Example inputs and options
Starting values are examples unless a field identifies a dated rule. Unit selectors convert only fields marked for conversion. Rates and model options keep the units and basis shown in their labels.
- Terminal clock anchor date
- Example: 2026-11-02
- Terminal clock ending date
- Example: 2026-11-12
- Count anchor date in this clock?
- Example: Include the anchor dateOptions: Exclude the anchor date; Include the anchor date
- Count ending date in this clock?
- Example: Include the ending dateOptions: Exclude the ending date; Include the ending date
- Free days
- Example: 3
- Calendar for consuming free days
- Example: Calendar daysOptions: Calendar days; Monday–Friday only; Calendar days except entered exclusions; Monday–Friday except entered exclusions
- Calendar for billed days after free time
- Example: Calendar daysOptions: Calendar days; Monday–Friday only; Calendar days except entered exclusions; Monday–Friday except entered exclusions
- How escalating rate-tier days advance
- Example: Count chargeable days onlyOptions: Count chargeable days only; Count all elapsed calendar days after free time
- Identical containers on this same clock
- Example: 1
- Rate tier start day
- Example: 1
- Daily rate (USD/container)
- Example: 100