An oil tanker, also known as a petroleum tanker, is a merchant ship designed for the bulk transport of oil. There are two basic types of oil tankers: crude tankers and product tankers. Crude tankers move large quantities of unrefined crude oil from its point of extraction to refineries.
Oil tankers are often classified by their size as well as their occupation. The size classes range from inland or coastal tankers of a few thousand metric tons of deadweight (DWT) to the mammoth ultra large crude carriers (ULCCs) of 550,000 DWT. Tankers move approximately 2,000,000,000 metric tons (2.2×109 short tons) of oil every year. Second only to pipelines in terms of efficiency,[3] the average cost of oil transport by tanker amounts to only two or three United States cents per 1 US gallon (3.8 L).
| AFRA Scale | Flexible market scale | ||
| Class | Size in DWT | Class | Size in DWT |
| General Purpose tanker | 10,000–24,999 | Product tanker | 10,000–60,000 |
| Medium Range tanker | 25,000–44,999 | Panamax | 60,000–80,000 |
| LR1 (Large Range 1) | 45,000–79,999 | Aframax | 80,000–120,000 |
| LR2 (Large Range 2) | 80,000–159,999 | Suezmax | 120,000–200,000 |
| VLCC (Very Large Crude Carrier) | 160,000–319,999 | VLCC | 200,000–320,000 |
