BenchReference

2.5 mm Drill

Decimal inches 0.0984″
Millimeters 2.5 mm
System Metric

Nearest equivalents in other systems

System Nearest drill Size Difference
Fractional inch 3/32″ 0.0938″ / 2.381 mm −0.119 mm (−0.0047″)
Number (wire gauge) #40 0.0980″ / 2.489 mm −0.011 mm (−0.0004″)
Letter A 0.2340″ / 5.944 mm +3.444 mm (+0.1356″)
−0.2 mm+0.2 mm2.5 mm2.4 mm−0.1 mm2.6 mm+0.1 mm3/32″−0.119 mm#40−0.011 mm← 2.3 mm −0.2 mm2.7 mm +0.2 mm →A +3.444 mm →tick position = true diameter · metric neighbors above, equivalents below · window ±0.2 mm
Positive difference = cuts a slightly larger hole than 2.5 mm. Sizes beyond the window are listed with arrows — they are not close substitutes.

Tap drill for

Thread Major diameter Pitch
M3 × 0.5 0.1181″ / 3 mm 0.5 mm

The standard chart recommendation (≈75% thread engagement). Application-specific factors — material, hole depth, tap type — can justify a different drill.

Neighboring metric sizes

Drill Decimal in mm vs 2.5 mm
2.3 mm 0.0906 2.3 −0.2 mm
2.4 mm 0.0945 2.4 −0.1 mm
2.5 mm 0.0984 2.5 —
2.6 mm 0.1024 2.6 +0.1 mm
2.7 mm 0.1063 2.7 +0.2 mm
Data provenance. ASME B94.11M, Twist Drills (standard drill size series) (ASME). Machinery’s Handbook — tap drill charts (Industrial Press). Millimeter and inch values are converted with the exact definition 1 in = 25.4 mm; the canonical dimension for this metric size is 2.5 mm. See all data sources.