The standard containers are the 20-foot and the 40-foot, both about 2.4 m wide outside. The 40’ high cube is roughly 30 cm taller than the standard and is now the most common choice for light, bulky cargo.
For special needs there is the reefer (refrigerated, with its own unit and less internal space), the open top (tarpaulin roof, for tall cargo loaded by crane) and the flat rack (no side walls or roof, for machinery and out-of-gauge pieces).
Actual internal dimensions vary by manufacturer and year; ask for the specific container’s data sheet before planning. The load planner uses typical values you can adjust.