SAE Thread Size Chart | Different Types of SAE Threads


Check out the SAE size chart to know about common thread dimensions including UNC, UNF, and UNEF, as well as types and measurements of SAE threads.

What are the Types of SAE Threads

SAE threads are often used in conjunction with other types of threads, such as NPT (National Pipe Thread) or BSP (British Standard Pipe) threads.

– Unified Coarse (UNC): the most commonly used thread type for general-purpose fastening applications. UNC threads have a 60-degree thread angle and a flat crest and root.

– Unified Fine (UNF): these threads have a smaller pitch than UNC threads and are used for applications where greater tensile strength is required. UNF threads have a 60-degree thread angle and a rounded crest and root.

– Unified Extra Fine (UNEF): these threads have an even smaller pitch than UNF threads and are used in applications that require even greater tensile strength. UNEF threads also have a 60-degree thread angle and a rounded crest and root.

– Unified National Special (UNS): these threads have a unique thread pitch and are used for specialized applications, such as aircraft and missile components.

– SAE Straight Thread: these threads have a cylindrical shape and are used for fluid and gas connections in hydraulic and pneumatic systems. SAE straight threads are commonly found on fittings and hoses.

– SAE Flared Tube Fittings: these fittings have a 45-degree flare and are commonly used for high-pressure fluid and gas connections. SAE flared tube fittings are commonly found on brake and fuel lines.

How is SAE Thread Size Measured?

SAE thread dimension is typically measured by its major diameter, which is the outside diameter of the threaded portion of the fastener or component. The major diameter is used to determine the size of the mating nut or hole.


To measure the major diameter of a threaded fastener, you can use a thread pitch gauge to determine the thread type (UNC, UNF, UNEF, etc.) and a caliper to measure the outside diameter of the threads. The measurement should be taken at the crest (top) of the threads for external threads or at the root (bottom) of the threads for internal threads.


Alternatively, you can use a thread micrometer, which is a specialized tool designed specifically for measuring the major diameter of threaded components. Thread micrometers have anvils that are shaped to fit the threads and measure the diameter with a calibrated screw.

SAE Thread Size (Dimension) Chart

Below is a chart with some common SAE thread dimensions and corresponding thread pitches. This is not an exhaustive table and there are lots of other SAE sizes.