Tracking · BL
Bill of lading tracking: how it works and what to expect
· 5 min read · Flettia team
You have the bill of lading in front of you and you want to know where the cargo is. It looks like the natural number to track with, and sometimes it is, but not always. This guide explains the difference between a BL number and a container number, why most trackers only take the second one, and how to pull from the BL itself what you need to see the voyage.
Two different numbers people mix up
The container number identifies the physical box and always has the same shape: four letters and seven digits, for example MSCU1234566. That shape is defined by ISO 6346, and the last digit is a check digit, so a mistyped number is caught on its own.
The bill of lading number identifies the transport document, not the box. There is no single format: every carrier builds its own, with its own length and its own mix of letters and digits. Many start with a four-letter carrier code, such as EGLV on Evergreen documents or ONEY on ONE's. One BL can cover several containers, and that is the key to everything below.
Why a BL is harder than a container number
A tracker that receives four letters and seven digits knows exactly what it has: it infers the carrier from the prefix and validates the check digit before querying anything. With a BL number it can do neither, because the format does not say which line it belongs to and cannot be verified.
Flettia's tracker takes all three numbers: container, bill of lading and booking. With a BL or a booking it asks which carrier it belongs to and then lists that shipment's containers. The limit is not ours: each carrier decides whether it allows a document search, so in some cases the container number is still the way.
How to pull the useful number out of the BL
- Open the BL and look for the “Container No.” or “Marks and Numbers” field. The containers of that shipment are listed there, in the same four letters and seven digits format.
- If the BL covers several containers, track each one separately: the vessel voyage is the same, but discharge, pickup and empty return can happen on different days.
- Within your contracted tracking service, use that number to look up the shipment. The prefix helps identify the container owner.
- If you don't have the BL at hand, the container number also appears on the booking confirmation, the packing list and the shipping advice your freight forwarder sends.
The leased box exception
There is one exception worth knowing. Many containers belong to a leasing company rather than to the carrier, and then the four letters are the lessor's, not the line's. For those boxes the tracker asks the carriers that allow it: today MSC, COSCO, Hapag-Lloyd, ONE, Evergreen, Yang Ming and PIL. A leased box travelling with Maersk isn't found on its own yet.
What to watch once you see the voyage
With the container located, the two dates that decide your money are discharge at the destination port, where free days usually start running, and gate out, which confirms the box is on a truck. Seeing them the day they happen is what lets you schedule pickup before demurrage starts.
Estimated dates are published by each carrier and change with the vessel's schedule. No tracker can promise an estimate will hold; what is useful is seeing when it moved and by how much.
Frequently asked questions
Can I track with a bill of lading number on Flettia?
Yes. Type the BL and the tracker asks which carrier; then it lists that shipment's containers. If that carrier doesn't allow a document search, use the container number printed on the BL itself.
Why does every carrier's BL look different?
Because there is no single format. Each line defines its own; the only common trait is that it often starts with a four-letter carrier code.
My BL covers several containers. Which one do I track?
Any of them shows the vessel voyage, but it is worth tracking each one: discharge and pickup can happen on different dates.
Does the booking number work?
Yes, bookings are accepted too and behave like a BL: you pick the carrier and the shipment's containers come up.
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