1-1/2 Nut Dimensions & Size

1-1/2″ hex nuts are commonly used with 1-1/2-inch bolts or threaded rods in heavy industrial equipment, structural steel assemblies, large machinery, construction frameworks, and marine or energy applications. They are designed to secure mating fasteners by providing internal threads that clamp components together when tightened against a surface or washer. Depending on the threads per inch (TPI), a 1-1/2″ hex nut may be specified as a 1-1/2-6 nut for coarse-thread applications or a 1-1/2-12 nut for fine-thread assemblies where higher holding strength, precise adjustment, or vibration resistance is required. While the TPI varies, the external hex dimensions—such as width across flats and thickness—remain standardized to ensure compatibility with large wrenches or spanners.

Disclaimer: Hex nut dimensions and tolerances may vary slightly by thread series (UNC, UNF, or special fine), manufacturer, material, finish, or strength grade. Always verify critical dimensions using the official manufacturer product datasheet before installation.

Hex nut diagram showing diameter, width across flats, width across corners, thickness, and wrench size
1-1/2 Hex Nut Dimensions – ANSI/ASME B18.2.2
Dimension Nominal Size Actual Size (in)
Min Max
Diameter 1-1/2 1.4480 1.5000
Width Across Flats 2-1/4 2.175 2.250
Width Across Corners Not specified 2.480 2.598
Thickness 1-9/32 1.245 1.317
Wrench Size 2-1/4 Not specified Not specified
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Frequently Asked Questions

What standard governs 1-1/2″ hex nuts?

1-1/2″ hex nuts in the United States are typically manufactured to the ANSI/ASME B18.2.2 standard, which defines their external dimensions, tolerances, and geometry for inch-series hex nuts.

What bolt size fits a 1-1/2″ hex nut?

A 1-1/2″ hex nut is designed to fit 1-1/2-inch diameter bolts or threaded rods, including common threads per inch such as 1-1/2-6 (UNC) and 1-1/2-12 (UNF), depending on the application.

What does “1-1/2″” mean on a hex nut?

“1-1/2″” refers to the nominal major diameter of the mating bolt or threaded rod, not the wrench size or the nut’s external dimensions.

Are all 1-1/2″ hex nuts the same?

No. While the external hex dimensions are standardized under ANSI/ASME B18.2.2, differences can occur due to threads per inch (1-1/2-6 vs 1-1/2-12), material, finish, strength grade, and manufacturer tolerances.

What is ANSI/ASME B18.2.2?

ANSI/ASME B18.2.2 is the American standard that defines the dimensional requirements, tolerances, and geometry for inch-series hex nuts, including finished hex nuts and heavy hex nuts. It ensures that nuts from different manufacturers remain interchangeable and compatible with standard tools and mating fasteners.