Oil tanker sizes range from general purpose to ultra-large crude carriers on AFRA scale

The global crude oil and refined product tanker fleet uses a classification system to standardize contract terms, establish shipping costs, and determine the ability of ships to travel into ports or through certain straights and channels. This system, known as the Average Freight Rate Assessment system, was created by Royal Dutch Shell six decades ago, and is overseen by the London Tanker Brokers' Panel, an independent group of shipping brokers.