Money-clock guide
The two clocks that cost importers the most.
Demurrage and per diem turn calendar days into invoices. Here's how the clocks actually run at NY / NJ, how to read your last free day, and the dispatch plays that beat them.
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Written by the Pig-Tainer dispatch desk · Updated 2026-08-03
Two clocks, two billers
Demurrage: the terminal's clock. It starts when your container discharges and free time begins, and it bills daily once free time lapses while the box is still on terminal ground. Rates escalate in tiers — the second week costs more per day than the first.
Per diem (the ocean side of detention): the steamship line's clock. It starts when the container leaves the terminal and bills daily once the line's free days lapse until the empty is returned to an accepted location. Different biller, different trigger, and — the trap — the two clocks overlap: pulling a box stops demurrage and starts per diem.
Free time and the last free day
Free time is the grace period each clock allows. Terminal free time at NY / NJ is measured in working days from availability; line free days are set by your contract or the line's tariff. The last free day (LFD) is the final day you can act without charges — and it is the single most important date in import operations.
LFD math has teeth: availability isn't discharge (a box can be off the vessel but unavailable behind a hold), working days aren't calendar days, and weekend/holiday gate schedules decide whether a theoretical free day is a usable one. A Friday-availability box with short free time can be burning money by Wednesday.
- Track LFD from availability, not discharge
- Holds (customs, line, terminal) can freeze usability but not always the clock — verify per event
- Weekends and gate closures eat usable days without pausing charges
- Every box on our operating record carries its LFD; at-risk boxes get flagged before the charge exists
An illustrative week of bad luck
Say a box becomes available Monday with five working free days — LFD the following Monday. The receiver can't take delivery until Thursday. Deliver Thursday, unload Friday, return the empty Monday and both clocks are beaten. Now slip the receiver to next Wednesday: two days of tier-one demurrage before pickup, and if unloading slips the weekend, per diem joins in. Using round illustrative numbers — a few hundred a day, escalating — that one receiver slip becomes four figures on one container. Multiply by a peak-season arrival of twenty boxes and the math explains itself.
The counter-move: pre-pull before LFD into a carrier yard, where a day costs a fraction of a demurrage day and never escalates, then deliver when the receiver is ready and return the empty inside line free days. This is the highest-ROI decision in drayage, and it only happens if someone is watching the clock before it expires.
Who watches the clocks
At most operations, the honest answer is 'whoever remembered to check the terminal site.' At ours, the clocks live on the container's operating record: availability, holds, LFD, and return deadlines feed dispatch automatically, and at-risk boxes surface before the money starts. That's the practical difference between drayage as trucking and drayage as container control.
Quick answers
- What is a last free day (LFD)?
- The final day of free time — the last day you can pick up a container (terminal clock) or return an empty (line clock) without daily charges. Track it from availability, in working days, per terminal schedule.
- Does a customs hold pause demurrage?
- Not reliably — hold behavior varies by terminal and situation. A box can be unavailable to you and still burning free time. Treat every held box as a live clock until verified otherwise.
- How does a pre-pull save money?
- It moves the box off terminal ground before the LFD, swapping escalating demurrage for flat, cheaper yard storage, and puts delivery timing back on your schedule. One yard day typically costs a fraction of one demurrage day.
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