The most common flag states

If you have read a maritime listicle in the last decade, you have read that Panama operates the largest merchant fleet in the world. It was true for a very long time. It is not true now. According to UNCTAD's Review of Maritime Transport 2024, Liberia has overtaken Panama as the largest register by deadweight tonnage — and most of the internet has not caught up.

This matters more than it sounds. Flag-state rankings underpin a lot of downstream reasoning about where regulatory leverage sits, which registries dominate the dry-bulk and tanker trades, and how the open-registry model has reshaped ownership. Leading with a stale fact quietly corrupts all of it. So here is the corrected picture, with the figures date-stamped.

The current top three (UNCTAD, 2024)

Measured by deadweight tonnage — the cargo-carrying capacity registered under each flag — the order at the top is now:

Rank	Flag state	Tonnage (≈)
1	Liberia	424M DWT
2	Panama	371M DWT
3	Marshall Islands	305M DWT

All three are open registries — they allow a shipowner to register a vessel under a flag with which the company has no genuine economic connection. Critics, including the trade-union movement, call these flags of convenience. The model offers lower fees, lighter tax and more flexible crewing rules, which is exactly why the three biggest registers in the world are not the three biggest shipowning nations.

Why Liberia pulled ahead

Liberia's register has grown fastest at the large-tonnage end — modern bulk carriers, tankers and the newest container ships. Because the ranking is measured by tonnage rather than headcount, a register that attracts a smaller number of very large hulls climbs quickly. Panama's fleet remains enormous by ship count, but its growth has been flatter, and Liberia's mix has tilted toward the high-DWT vessels that move the needle.

A flag-state ranking is only as current as its date stamp. The single most common stale fact in maritime writing is that Panama leads — Liberia has. UNCTAD, Review of Maritime Transport 2024

Count by ships, not tonnage, and the picture shifts

Rankings move depending on what you count. By deadweight tonnage the order is Liberia, Panama, Marshall Islands. Count by number of registered ships instead and Panama's huge fleet of smaller and older vessels reasserts itself near the top. Count by gross tonnage and you get a third arrangement again. None of these is "wrong" — they answer different questions, which is precisely why a single headline number should always carry its unit and its date.

This is also why what a flag state actually is matters to the reading. A flag is not where a ship was built or where its owner sits; it is the country whose law governs the vessel and whose authorities are responsible for inspecting it. The concentration of tonnage under a handful of open registries is the reason the port-state-control regime exists at all: it lets the port countries check ships that the flag state may not be policing closely.

How to read flag data without getting it wrong

Three rules keep you honest. First, name the metric — DWT, GT or ship count. Second, name the date — registers move year to year, and sanctions-driven reflagging has accelerated the churn. Third, check against a live source rather than a static list, because the gap between a 2019 listicle and the 2024 data is exactly the Panama-versus-Liberia error.

That last point is where a live registry earns its keep. Every vessel file in the Marifest registry records the flag the ship currently flies, sourced from open reference data, so you can filter the fleet by flag and read the live count instead of trusting a headline. When a vessel reflags — a common move for ships trying to shed a compliance history — the change shows up against its permanent IMO number, not buried in a static table that nobody updated.