Panamax
Panamax describes a vessel built to the maximum dimensions that could pass through the original locks of the Panama Canal — historically about 32.3 m in beam, roughly 294 m long and around 12 m draft. For decades this was a defining size limit in ship design, since a ship built any larger could not use this vital shortcut between the Atlantic and Pacific.
In container shipping a Panamax vessel carries roughly 4,000–5,000 TEU. The 2016 canal expansion added larger locks, creating the bigger Neo-Panamax (or New Panamax) class (around 366 m long, 49 m beam, ~14,000 TEU); ships too large even for the new locks are post-Panamax. Vessel-size classes like Panamax — alongside Handysize, Aframax, Suezmax, Capesize and ULCS — are standard shorthand for a ship's capacity and which waterways it can use, and shape route planning and port capability.
Ship-size classes are the shorthand of shipping, and Panamax is the classic one — it tells you a vessel's rough capacity and, crucially, which canals and ports it can use. Since a canal's locks can dictate global ship design, knowing the Panamax and Neo-Panamax limits explains a lot about how and where cargo moves.
What is Neo-Panamax?
The larger class of ship able to use the Panama Canal's expanded locks opened in 2016 — bigger than the original Panamax limit.
How many TEU does a Panamax container ship carry?
Roughly 4,000–5,000 TEU; Neo-Panamax ships carry around 12,000–14,000 TEU.