postPanamax

PostPanamax, often written as Post-Panamax, is a shipping term used to describe vessels that are too large to transit the Panama Canal under its original constraints. It contrasts with Panamax, which referred to ships sized to pass through the canal before its expansion. The designation helps explain why certain ships must detour or be scheduled differently in global trade networks.

Before the 2016 expansion, the Panama Canal set maximum dimensions for ships passing through the original locks: about 965 feet (294 meters) in length, a beam of 106 feet 8 inches (32.3 meters), and a draft around 39 feet 6 inches (12.0 meters). Vessels exceeding any of these limits were considered post-Panamax. This category includes many large container ships, bulk carriers, and tankers built in the late 20th and early 21st centuries; post-Panamax container ships commonly range from roughly 5,000 to 10,000 TEU.

The Panama Canal expansion, completed in 2016, introduced a new class of ships known as New Panamax or Neo-Panamax. The expanded locks accommodate vessels up to roughly 366 meters (1,200 feet) in length, about 49–50 meters in beam, and around 15 meters in draft, enabling container ships in the neighborhood of 13,000–14,000 TEU. In practice, some ships larger than Panamax fall into the post-Panamax category in historical usage, though terminology varies by port and carrier.

The term highlights canal constraints rather than ship efficiency, and it has influenced port development, navigation planning, and vessel design as routes adjust to increasingly large global fleets.