Tanker Size
There are different sizes of tankers used in the international transportation of oil, from a modest coastal tanker to a VLCC or ULCC Supertanker. The common rule is that the volume that can be carried in a tanker increases as a function of the cube of its length. For instance, a ULCC is about twice the length of a coastal tanker (415 meters versus 205 meters), but can carry about 8 times the volume (50,000 tons versus 400,000 tons). Because of their huge mass, tankers have a large inertia, making them very difficult to steer. A loaded supertanker could take as much as 3 kilometers and 15 minutes to come to a full stop and has a turning diameter of about 2 kilometers. Among the main tanker classes are:
| Class | Length | Beam | Draft | Overview |
| Coastal Tanker | 205 m | 29 m | 16 m | Less than 50,000 deadweight tons, mainly used for transportation of refined products (gasoline, gasoil). |
| Aframax | 245 m | 34 m | 20 m | Approximately 80,000 deadweight tons (American Freight Rate Association). |
| Suezmax | 285 m | 45 m | 23 m | Between 125,000 and 180,000 deadweight tons, originally the maximum capacity of the Suez Canal. |
| VLCC | 350 m | 55 m | 28 m | Very Large Crude Carrier. Up to around 300,000 deadweight tons of crude oil. |
| ULCC | 415 m | 63 m | 35 m | Ultra Large Crude Carrier. Capacity exceeding 300,000 deadweight tons. The largest tankers ever built have a deadweight of over 550,000 deadweight tons. |