Demurrage & Detention Cost Calculator

How it works

Chargeable days = days on the clock − free days − waived days; charge = Σ chargeable days × tier rate (days 1–4 at rate 1, then rate 2; an optional third tier after a set number of days); demurrage clock: discharge → gate-out; detention clock: gate-out → empty return; combined (merged) free time: one clock from discharge → empty return; working-day free time skips weekends and holidays, then every calendar day is charged; storage = days past the terminal’s free time × daily storage rate; shipment total = per-box total × containers

Ocean carriers give importers a few free days to collect a container after the ship discharges (demurrage covers the box sitting in the terminal) and a further allowance to unload it and return the empty (detention covers the box outside the port). Some lines merge them into one combined free time and one tariff from discharge to empty return — switch “Free time” to Combined for that. Once free time runs out, escalating daily tariffs apply per container, so a four-box shipment stuck a week over the allowance can rack up thousands that dwarf the original freight. Enter the dates (or day counts), choose whether free time is counted in calendar or working days and list any holidays, and the calendar tells you the last free day, when the empty is due back, and what every further day costs; the day-by-day table shows which tier each day falls in. Under More options you can change the tier lengths and add a third tier, count the event day as day 1 if your tariff does, remove days the carrier agreed to waive, and add terminal storage, which the terminal bills separately. The “moving faster” table puts a price on each day saved — the strongest argument for booking trucking and empty returns before the vessel arrives, and for negotiating extra free time in the contract.

Worked example

Four containers discharged with 5 free days, collected on day 9: 4 days of demurrage at $150 = $600 each. Returned 12 days after pickup against 7 free days: 5 days of detention — 4 × $100 + 1 × $175 = $575 each. Total $1,175 per box, $4,700 for the shipment; every further day now costs $1,700 (4 × ($250 + $175)). Picking up two days earlier would have saved $1,200; returning the empties two days earlier, $750. With a combined 12-day allowance instead, the 21 days from discharge to return give 9 chargeable days — 4 × $150 + 5 × $250 = $1,850 per box.

Sources: Federal Maritime Commission — Final rule on detention and demurrage billing practices · Maersk — U.S. import detention tariff (2026)

Frequently asked questions