The original lock chambers are 110 ft (33.53 m) wide by 1,050 ft (320 m) long, with a usable length of 1,000 ft (305 m). These dimensions determine the maximum size of ships that can use the canal; this size is known as Panamax. The new larger size of ships, called New Panamax, are about one and a half times the previous Panamax size and can carry over twice as much cargo.

The original canal has two lanes, each with its own set of locks. The expansion project added a third lane through the construction of lock complexes at each end of the canal. One lock complex is located on the Pacific side, southwest of the existing Miraflores Locks. The other is located east of the existing Gatun Locks. Each of these new lock complexes have three consecutive chambers designed to move vessels from sea level to the level of Gatun Lake and back down again.

The new lock chambers are 427 m (1,400.92 ft) long, 55 m (180.45 ft) wide, and 18.3 m (60.04 ft) deep. They use rolling gates instead of miter gates, which are used by the original locks. Rolling gates are used in almost all existing locks with dimensions similar to the new ones, and are a proven technology. The new locks use tugboats to position the vessels instead of electric locomotives (“mules”).