METRICcoarse60° flankISO 261

M8 × 1.25 Thread Dimensions

M8 x 1.25 is a coarse ISO Metric thread. Pitch is 1.25 mm, equivalent to 20.32 threads per inch. The recommended tap drill is nominal diameter minus pitch.

Major Ø8 mm
Pitch1.25 mm
Threads per inch20.32
Pitch Ø7.19 mm
Tap drill6.75 mm

Thread profile

millimetres unless stated
Thread profile — M8 x 1.25d 8d2 7.19d3 6.47mm60°P 1.25h3 0.767tap ⌀6.75
M8 × 1.25 — basic profile60° flank angle · Not to scale

Basic information

Designation
M8 x 1.25
Thread system
ISO Metric
Series
coarse
Standard
ISO 261
Basic profile
ISO 68-1 basic profile
Flank angle
60°

Dimensions

Major diameter
8 mm
Pitch
1.25 mm
Threads per inch
20.32
Pitch diameter
7.19 mm
Minor diameter (external)
6.47 mm
Minor diameter (internal)
6.65 mm
Thread depth
0.767 mm
Recommended tap drill
Ø 6.75 mm

How these values are derived

computed from the basic profile

These figures follow the ISO 68-1 basic profile of ISO 261. A 60° basic profile has a fundamental triangle height H = 0.866025 × P, with pitch diameter d₂ = d − 0.649519 × P, external minor diameter d₃ = d − 1.226869 × P and internal minor diameter D₁ = d − 1.082532 × P; the two minor diameters differ because the external root is rounded while the internal crest is truncated. The recommended tap drill is given as nominal diameter minus pitch, which approximates 75% thread engagement — adjust it for tough materials or deep holes.

Compatible parts226 specification pages

All M8 fasteners

Every fastener below is threaded M8 × 1.25, so a nut, bolt or washer picked from this list will mate with it.

DIN 912ISO 4762DIN 7991ISO 10642ISO 7380DIN 7984DIN 933ISO 4017DIN 931ISO 4014DIN 934ISO 4032DIN 439ISO 4035DIN 985ISO 10511ISO 4161DIN 6923DIN 916DIN 914DIN 915DIN 913ISO 4029ISO 4027ISO 4028ISO 4026DIN 84ISO 1207DIN 85ISO 1580DIN 963ISO 2009
SpecificationLength
DIN 912 M8 × 12 Hexagon Socket Head Cap Screw12 mm
DIN 912 M8 × 16 Hexagon Socket Head Cap Screw16 mm
DIN 912 M8 × 20 Hexagon Socket Head Cap Screw20 mm
DIN 912 M8 × 25 Hexagon Socket Head Cap Screw25 mm
DIN 912 M8 × 30 Hexagon Socket Head Cap Screw30 mm
DIN 912 M8 × 35 Hexagon Socket Head Cap Screw35 mm
DIN 912 M8 × 40 Hexagon Socket Head Cap Screw40 mm
DIN 912 M8 × 50 Hexagon Socket Head Cap Screw50 mm
DIN 912 M8 × 60 Hexagon Socket Head Cap Screw60 mm
DIN 912 M8 × 80 Hexagon Socket Head Cap Screw80 mm
ISO 4762 M8 × 12 Hexagon Socket Head Cap Screw12 mm
ISO 4762 M8 × 16 Hexagon Socket Head Cap Screw16 mm
ISO 4762 M8 × 20 Hexagon Socket Head Cap Screw20 mm
ISO 4762 M8 × 25 Hexagon Socket Head Cap Screw25 mm
ISO 4762 M8 × 30 Hexagon Socket Head Cap Screw30 mm
ISO 4762 M8 × 35 Hexagon Socket Head Cap Screw35 mm
ISO 4762 M8 × 40 Hexagon Socket Head Cap Screw40 mm
ISO 4762 M8 × 50 Hexagon Socket Head Cap Screw50 mm
ISO 4762 M8 × 60 Hexagon Socket Head Cap Screw60 mm
ISO 4762 M8 × 80 Hexagon Socket Head Cap Screw80 mm
DIN 7991 M8 × 12 Hexagon Socket Countersunk Head Screw12 mm
DIN 7991 M8 × 16 Hexagon Socket Countersunk Head Screw16 mm
DIN 7991 M8 × 20 Hexagon Socket Countersunk Head Screw20 mm
DIN 7991 M8 × 25 Hexagon Socket Countersunk Head Screw25 mm
DIN 7991 M8 × 30 Hexagon Socket Countersunk Head Screw30 mm
DIN 7991 M8 × 35 Hexagon Socket Countersunk Head Screw35 mm
DIN 7991 M8 × 40 Hexagon Socket Countersunk Head Screw40 mm
DIN 7991 M8 × 50 Hexagon Socket Countersunk Head Screw50 mm
DIN 7991 M8 × 60 Hexagon Socket Countersunk Head Screw60 mm
DIN 7991 M8 × 80 Hexagon Socket Countersunk Head Screw80 mm
ISO 10642 M8 × 12 Hexagon Socket Countersunk Head Screw12 mm
ISO 10642 M8 × 16 Hexagon Socket Countersunk Head Screw16 mm
ISO 10642 M8 × 20 Hexagon Socket Countersunk Head Screw20 mm
ISO 10642 M8 × 25 Hexagon Socket Countersunk Head Screw25 mm
ISO 10642 M8 × 30 Hexagon Socket Countersunk Head Screw30 mm
ISO 10642 M8 × 35 Hexagon Socket Countersunk Head Screw35 mm
ISO 10642 M8 × 40 Hexagon Socket Countersunk Head Screw40 mm
ISO 10642 M8 × 50 Hexagon Socket Countersunk Head Screw50 mm
ISO 10642 M8 × 60 Hexagon Socket Countersunk Head Screw60 mm
ISO 10642 M8 × 80 Hexagon Socket Countersunk Head Screw80 mm

Showing the first 40 of 226 specification pages.

Related

Other pitches at the same 8 mm diameter — a fine pitch on a coarse diameter, or the reverse, is the usual substitution question.

M8 × 1 fineM8 × 0.75 fine

Neighbouring sizes in ISO Metric.

M6 × 1M6 × 0.75 fineM7 × 1M7 × 0.75 fineM8 × 1 fineM8 × 0.75 fineM9 × 1.25M9 × 1 fine