Machinist reference

Every thread, drill & torque — from the standard.

Tap drills, clearance holes, pitch and minor diameters, torque estimates and wrench sizes for 228+ metric, Unified and pipe threads. Every number is generated from the published standard formulas and checked against known reference values.

Browse the size reference Identify a thread

228

Thread sizes referenced

D − P

Metric tap-drill rule, per size

T = K·F·d

Torque with a stated K factor

ISO · ASME

Standard formulas & tables

Browse by system

Metric, Unified & pipe threads

Metric99 sizesISO metric coarse & fine, M1–M64 Unified99 sizesUNC · UNF · UNEF · UN, #0–2½"Pipe30 sizesNPT · BSPT (R) · BSPP (G)

Popular sizes

Straight to the common threads

The sizes people look up most — tap drill on every card.

M3 × 0.5Tap 2.5 mmØ 3 mm · pitch 0.5 mm M4 × 0.7Tap 3.3 mmØ 4 mm · pitch 0.7 mm M5 × 0.8Tap 4.2 mmØ 5 mm · pitch 0.8 mm M6 × 1.0Tap 5 mmØ 6 mm · pitch 1 mm M8 × 1.25Tap 6.75 mmØ 8 mm · pitch 1.25 mm M10 × 1.5Tap 8.5 mmØ 10 mm · pitch 1.5 mm 1/4-20 UNCTap #7Ø 6.35 mm · pitch 1.27 mm 3/8-16 UNCTap 5/16"Ø 9.525 mm · pitch 1.588 mm 1/2-13 UNCTap 27/64"Ø 12.7 mm · pitch 1.954 mm 1/2-14 NPTTap 17.86 mmØ 21.34 mm · pitch 1.814 mm

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Measured a fastener and don't know what it is? Feed the identifier its outside diameter and pitch (or TPI) and it ranks the candidates. Need a hole size? The tap-drill calculator covers every size in the database — free, no sign-up.

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