BenchReference

M22 × 2.5 Thread

Recommended tap drill 19.5 mm
Tap drill Ø 0.7677″ / 19.5 mm
Major Ø 0.8661″ / 22 mm
Pitch 2.5 mm

The chart recommendation gives approximately 77% thread engagement — the conventional target for average materials. It is not the only valid choice; see the options below.

Specification

DesignationM22 × 2.5
Thread familyISO metric coarse
Nominal sizeM22
Basic major diameter 0.8661″ / 22 mm
Pitch2.5 mm
Recommended tap drill 19.5 mm (0.7677″ / 19.5 mm)
P = 2.5 mm 60° major Ø 22 mm 60° thread form (UN / ISO) — schematic

Tap drill options by thread engagement

Any of these standard drills produces a usable engagement for M22 × 2.5; smaller drills give stronger threads but higher tapping torque. Percentages use the conventional approximation (60° thread form).

49/64″ 78.6% 19.5 mm ★ 77% 20 mm 61.6% shaded = share of the full thread height the tap forms · accent line = drilled hole wall
★ = chart recommendation. A smaller drill leaves more of the thread height for the tap to form.
Drill Decimal in mm Approx. engagement
49/64″ 0.7656 19.447 78.6%
19.5 mm — chart recommendation 0.7677 19.5 77%
25/32″ 0.7813 19.844 66.4%
20 mm 0.7874 20 61.6%

Nearest drills to the tap drill in other systems

Drill Size vs 19.5 mm Resulting engagement
49/64″ 0.7656″ / 19.447 mm −0.053 mm 78.6%

Clearance holes

For a bolt or screw of this size to pass through freely. ISO 273 series (fine/medium/coarse), shown as close, normal, and loose.

Tapped hole Clearance hole 19.5 mm tap drill threads cut into the material 24 mm (normal fit) the tinted gap lets the bolt pass freely
Schematic — proportions exaggerated for clarity; use the table values.
Fit Drill / Ø Decimal in mm
close 23 mm 0.9055 23
normal 24 mm 0.9449 24
loose 26 mm 1.0236 26

Hex bolt & nut dimensions

For a standard hex bolt (ISO 4014/4017) and style-1 nut (ISO 4032) in this size.

Wrench / socket size (bolt head) 34 mm — legacy DIN: 32 mm
Head height 14 mm
Nut thickness 19.4 mm
Compatible nut M22 × 2.5 hex nut
Head — top view Bolt — side view Nut — side view width across flats = 34 mm wrench head height 14 mm thickness 19.4 mm

Basic (nominal) dimensions. See the wrench & socket size charts for all sizes and the metric ↔ SAE socket comparison.

Related threads

Data provenance. ISO 261 / ISO 724, ISO general purpose metric screw threads (ISO). ISO 2306, Drills for use prior to tapping screw threads (ISO). ISO 273, Clearance holes for bolts and screws (ISO). ISO 4014 / ISO 4017, Hexagon head bolts and screws (ISO). ISO 4032, Hexagon regular nuts, style 1 (ISO). Engagement percentages use the conventional approximation (engagement = (major − drill) ÷ (1.29904 × pitch)) and are guidance, not a tolerance specification. See all data sources.