# Tolerance on bolt major diameters

What are the tolerance specs on the major diameter of imperial bolts?

Specifically, a 1/4-20 imperial bolt has a major diameter of 0.25in, but what is the tolerance on that dimension. I (and everyone I've asked) have always taken that value to be exact, but that's obviously incorrect.

• Thread only or shank? – Solar Mike Sep 8 '17 at 16:18
• Just the major diameter on the threads. I've found a few standards docs with tolerances on unthreaded shanks, but nothing on the threaded portion. – Diesel Sep 8 '17 at 16:19

class 2: 0.2408 < d < 0.2489