Metric Tap Drill Reference
Common coarse sizes
- M3 × 0.5 → 2.5 mm
- M4 × 0.7 → 3.3 mm
- M5 × 0.8 → 4.2 mm
- M6 × 1.0 → 5.0 mm
- M8 × 1.25 → 6.8 mm
- M10 × 1.5 → 8.5 mm
- M12 × 1.75 → 10.2 mm
Rule of thumb
Tap Drill (mm) = Major Diameter − Pitch
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Tap drill sizes for standard ISO metric coarse threads.
Formula
Tap Drill (mm) = Major Diameter − PitchUnits: mm
Machine-readable reference
Structured metadata for formulas, tags, canonical status, and future diagram support.
Slug
tap-drill-metric
Category
Threads & Fasteners
Canonical
Yes
Updated
4/23/2026
Units
mm
Tags
tap, drill, metric, ISO
Source
Machinery's Handbook, 31st ed., Threads
Tap Drill (mm) = Major Diameter − Pitch
Source: Machinery's Handbook, 31st ed., Threads