The Meaning of SAE in Tools
By: Leon Rhodes
SAE stands for Society of Automotive Engineers. SAE is a measurement system used primarily on tools and fasteners made in the USA. Tools in the United States, such as wrenches and sockets, are often available in SAE sizes measured in inches and fractions of inches.

Outside of the USA the metric measurement system is most widely used. The metric system is a measurement system based on millimeters(mm), not inches. There is no practical exact conversion between the two measurement systems when it comes to tools.
What does SAE stand for?
SAE stands for Society of Automotive Engineers. Early American car manufacturers invented the SAE system to standardize tool and fastener sizes for mechanics and home users. Since SAE and metric sizes differ slightly it is often difficult to use tools of one system with fasterners of the other.
What are SAE sizes?
SAE sizes are based on inches and fractions of inches. A 1 inch wrench, for example, measures exactly one inch in span where it connects with a fastener. A larger fastener, typically a bolt, requires a larger wrench. SAE sizes are full, 1/2, 1/4, 1/8, 1/16 and 1/32nd of an inch.
What is an SAE socket?
An SAE socket is a tool that uses inches as it's measurement system instead of a metric socket which uses millimeters(mm). SAE sockets and wrenches are more widely used in America, especially with American automobiles, than in other countries.