UNCcoarse60° flank

5/8-11 UNC Thread Dimensions

5/8-11 UNC is a coarse pitch UNC thread. There are 11 threads per inch, giving a pitch of 2.31 mm. The recommended tap drill leaves roughly 75% thread engagement.

Nominal Ø15.88 mm
Pitch2.31 mm
Threads per inch11
Pitch Ø-22.22 mm
Tap drill-42.78 mm

Thread profile

millimetres unless stated
Thread profile — 5/8-11 UNCd 15.88d2 -22.22d3 -56.08mm60°P 2.31h3 35.98tap ⌀-42.78
5/8-11 UNC — basic profile60° flank angle · Not to scale
Designation
5/8-11 UNC
Thread system
UNC
Series
coarse
Flank angle
60°
Major diameter
15.88 mm / 0.62"
Pitch
2.31 mm
Threads per inch
11
Pitch diameter
-22.22 mm
Minor diameter (external)
-56.08 mm
Minor diameter (internal)
-47.62 mm
Thread depth
35.98 mm
Recommended tap drill
Ø -42.78 mm / -1.6841"

How these values are derived

Basic ISO thread geometry uses the fundamental triangle height H = 0.866025 × P. External minor diameter d₃ = d − 1.226869 × P, internal minor diameter D₁ = d − 1.082532 × P. Tap drill is given as nominal diameter minus pitch, which approximates a 75% thread engagement — adjust for tough materials or deep holes.