What is a Panamax size vessel?

Panamax vessels, are the maximum sized vessels that can pass through the Panama canal. These tankers vary in length size, ranging from 200 to 250 metres (650 and 820 feet) and have capacity range of 50,000 to 80,000 deadweight tons (DWTs). which equate to a range of 350,000 to 500,000 barrels.