Acorn Nut Sizes and Dimensions Chart for SAE recommended low and high crown acorn nuts. The charts of acorn nuts are given in the SAE J483a standard.

Acorn nut is a type of nut used with bolts to clamp the parts together. The difference between hex nuts and acorn nut is that acorn nuts are closed nuts and they protect male threads. Acorn nuts are also used for decorative purposes. There are two types of acorn nuts which are low crown and high crown.

Some important notes from the SAE J483a:

- The diameter range of acorn nuts is from 0.1380 to 1.2500 inches according to standard.

- Threads are Unified Standard Class 2B, UNC or UNF Series.

Acorn Nut Sizes and Dimensions Chart:

Nominal size
Nut Type 


Dimensions of Acorn Nuts
Parameter Value (inch)
Product Name -- ---
Nominal Diameter d ---
Width Across Flats [F] Fmax ---
Fmin ---
Width Across Corners [G] Gmax  ---
Gmin ---
Body Diameter A ---
Overall Height  H ---
Hexagon Height Q ---
Nose Radius R ---
Body Radius S ---
Maximum Drill Depth Tmax ---
Minimum Full Thread Umin ---


Unified Screw Thread: A thread form used by the United Kingdom, Canada, and the United States to obtain screw thread interchangeability among these three nations. It has 60° thread angle and dimensions are stated in inch units.

UN form screw threads: The UN thread is intended for general purpose fastening operations.

UNC (Unified National Coarse): Most commonly used type for general engineering applications. This thread form is used in materials with low tensile strength which makes threads more resistance against stripping (internal threads) .UNC give possibility for quick assembly.

UNF (Unified National Fine): External threads of this Fine Series have greater tensile stress area than comparable sizes of the coarse series. The Fine series is suitable when the resistance to stripping of both external and mating internal threads equals or exceeds the tensile load carrying capacity of the externally threaded member. It is also used where the length of engagement is short, where a smaller lead angle is desired, where the wall thickness demands a fine pitch, or where finer adjustment is needed.

Thread class: A classification system to classify the threads for interchangeability and manufacturability. Class 1 threads are loosely fitting thread and used for ease of assembly. Most commonly used class is 2 and this class is designed for general use. Class 3 is used for closer tolerances.


Link Usage
Unified Inch Screw Thread Sizes & Tolerances Calculator Calculates basic major, minor and pitch diameters of the external (bolt) and internal (nut) inch thread according to ASME B1.1-2003 standard. In addition to basic size calculations, limits of sizes calculations of different tolerance classes can be done according to same standard.


  • Oberg, E. , Jones ,F.D. , Horton H.L. , Ryffel H.H., (2016) . Machinery's Handbook . 30th edition.  Industrial Press Inc. , pp 1599
  • ASME B18.2.1-1996, Square and Hex Bolts and Screws (Inch Series)