01 · FIND A THREAD

Search by thread size

Try spaces, hyphens or × — common workshop formats are recognised.

Recent searches

Your last five thread sizes will stay on this device.

02 · SELECTED THREAD

M8 × 1.25

Metric Coarse

Standard / Recommended tapping drill6.8 mm≈ 6.8 mm

Drill designation6.8 mmmetric drill

Decimal inches0.267717 inexact conversion

Metric equivalent6.8 mm25.4 mm per inch

Clearance holes — not tapping drillsClose · Normal · Loose

Close fit8.4 mm

Normal fit9 mm

Loose fit10 mm

Major diameter8 mm

Pitch1.25 mm

Threads / inch20.32

Thread form60° · parallel

ISO metric coarse thread. The tapping drill is a recognised cut-tap workshop recommendation.

Custom thread engagementCalculated alternative — never replaces the recognised drill above.

Desired engagement%

Calculated alternative6.863 mmApproximate 60° straight cut-thread geometry

VERIFIED BROWSE TABLE

Thread sizes at a glance.

141 of 141 verified entries shown. Tap any row and the selected result will move into view.

Thread	Standard	Major Ø	Pitch / TPI	Recommended tap drill	Normal clearance
M1.6 × 0.35	Metric Coarse	1.6 mm	0.35 mm	1.25 mm1.25 mm	1.8 mm
M2 × 0.4	Metric Coarse	2 mm	0.4 mm	1.6 mm1.6 mm	2.4 mm
M2.5 × 0.45	Metric Coarse	2.5 mm	0.45 mm	2.05 mm2.05 mm	2.9 mm
M3 × 0.5	Metric Coarse	3 mm	0.5 mm	2.5 mm2.5 mm	3.4 mm
M4 × 0.7	Metric Coarse	4 mm	0.7 mm	3.3 mm3.3 mm	4.5 mm
M5 × 0.8	Metric Coarse	5 mm	0.8 mm	4.2 mm4.2 mm	5.5 mm
M6 × 1	Metric Coarse	6 mm	1 mm	5 mm5 mm	6.6 mm
M8 × 1.25	Metric Coarse	8 mm	1.25 mm	6.8 mm6.8 mm	9 mm
M10 × 1.5	Metric Coarse	10 mm	1.5 mm	8.5 mm8.5 mm	11 mm
M12 × 1.75	Metric Coarse	12 mm	1.75 mm	10.2 mm10.2 mm	13.5 mm
M14 × 2	Metric Coarse	14 mm	2 mm	12 mm12 mm	15.5 mm
M16 × 2	Metric Coarse	16 mm	2 mm	14 mm14 mm	17.5 mm
M18 × 2.5	Metric Coarse	18 mm	2.5 mm	15.5 mm15.5 mm	20 mm
M20 × 2.5	Metric Coarse	20 mm	2.5 mm	17.5 mm17.5 mm	22 mm
M22 × 2.5	Metric Coarse	22 mm	2.5 mm	19.5 mm19.5 mm	24 mm
M24 × 3	Metric Coarse	24 mm	3 mm	21 mm21 mm	26 mm
M27 × 3	Metric Coarse	27 mm	3 mm	24 mm24 mm	30 mm
M30 × 3.5	Metric Coarse	30 mm	3.5 mm	26.5 mm26.5 mm	33 mm
M33 × 3.5	Metric Coarse	33 mm	3.5 mm	29.5 mm29.5 mm	36 mm
M36 × 4	Metric Coarse	36 mm	4 mm	32 mm32 mm	39 mm
M8 × 1	Metric Fine	8 mm	1 mm	7 mm7 mm	9 mm
M10 × 1	Metric Fine	10 mm	1 mm	9 mm9 mm	11 mm
M10 × 1.25	Metric Fine	10 mm	1.25 mm	8.8 mm8.8 mm	11 mm
M12 × 1.25	Metric Fine	12 mm	1.25 mm	10.8 mm10.8 mm	13.5 mm
M12 × 1.5	Metric Fine	12 mm	1.5 mm	10.5 mm10.5 mm	13.5 mm
M14 × 1.5	Metric Fine	14 mm	1.5 mm	12.5 mm12.5 mm	15.5 mm
M16 × 1.5	Metric Fine	16 mm	1.5 mm	14.5 mm14.5 mm	17.5 mm
M18 × 1.5	Metric Fine	18 mm	1.5 mm	16.5 mm16.5 mm	20 mm
M18 × 2	Metric Fine	18 mm	2 mm	16 mm16 mm	20 mm
M20 × 1.5	Metric Fine	20 mm	1.5 mm	18.5 mm18.5 mm	22 mm
M20 × 2	Metric Fine	20 mm	2 mm	18 mm18 mm	22 mm
M22 × 1.5	Metric Fine	22 mm	1.5 mm	20.5 mm20.5 mm	24 mm
M22 × 2	Metric Fine	22 mm	2 mm	20 mm20 mm	24 mm
M24 × 2	Metric Fine	24 mm	2 mm	22 mm22 mm	26 mm
M27 × 2	Metric Fine	27 mm	2 mm	25 mm25 mm	30 mm
M30 × 2	Metric Fine	30 mm	2 mm	28 mm28 mm	33 mm
M33 × 2	Metric Fine	33 mm	2 mm	31 mm31 mm	36 mm
M36 × 3	Metric Fine	36 mm	3 mm	33 mm33 mm	39 mm
#2-56 UNC	UNC	2.184 mm	56 TPI · 0.454 mm	#501.778 mm	—
#3-48 UNC	UNC	2.515 mm	48 TPI · 0.529 mm	#471.994 mm	—
#4-40 UNC	UNC	2.845 mm	40 TPI · 0.635 mm	#432.261 mm	—
#5-40 UNC	UNC	3.175 mm	40 TPI · 0.635 mm	#382.578 mm	—
#6-32 UNC	UNC	3.505 mm	32 TPI · 0.794 mm	#362.705 mm	—
#8-32 UNC	UNC	4.166 mm	32 TPI · 0.794 mm	#293.454 mm	—
#10-24 UNC	UNC	4.826 mm	24 TPI · 1.058 mm	#253.797 mm	—
#12-24 UNC	UNC	5.486 mm	24 TPI · 1.058 mm	#164.496 mm	—
1/4-20 UNC	UNC	6.35 mm	20 TPI · 1.27 mm	#75.105 mm	—
5/16-18 UNC	UNC	7.938 mm	18 TPI · 1.411 mm	F6.528 mm	—
3/8-16 UNC	UNC	9.525 mm	16 TPI · 1.588 mm	5/167.938 mm	—
7/16-14 UNC	UNC	11.113 mm	14 TPI · 1.814 mm	U9.347 mm	—
1/2-13 UNC	UNC	12.7 mm	13 TPI · 1.954 mm	27/6410.716 mm	—
9/16-12 UNC	UNC	14.288 mm	12 TPI · 2.117 mm	31/6412.303 mm	—
5/8-11 UNC	UNC	15.875 mm	11 TPI · 2.309 mm	17/3213.494 mm	—
3/4-10 UNC	UNC	19.05 mm	10 TPI · 2.54 mm	21/3216.669 mm	—
7/8-9 UNC	UNC	22.225 mm	9 TPI · 2.822 mm	49/6419.447 mm	—
1-8 UNC	UNC	25.4 mm	8 TPI · 3.175 mm	7/822.225 mm	—
#2-64 UNF	UNF	2.184 mm	64 TPI · 0.397 mm	#501.778 mm	—
#3-56 UNF	UNF	2.515 mm	56 TPI · 0.454 mm	#452.083 mm	—
#4-48 UNF	UNF	2.845 mm	48 TPI · 0.529 mm	#422.375 mm	—
#5-44 UNF	UNF	3.175 mm	44 TPI · 0.577 mm	#372.642 mm	—
#6-40 UNF	UNF	3.505 mm	40 TPI · 0.635 mm	#332.87 mm	—
#8-36 UNF	UNF	4.166 mm	36 TPI · 0.706 mm	#293.454 mm	—
#10-32 UNF	UNF	4.826 mm	32 TPI · 0.794 mm	#214.039 mm	—
#12-28 UNF	UNF	5.486 mm	28 TPI · 0.907 mm	#144.623 mm	—
1/4-28 UNF	UNF	6.35 mm	28 TPI · 0.907 mm	#35.41 mm	—
5/16-24 UNF	UNF	7.938 mm	24 TPI · 1.058 mm	I6.909 mm	—
3/8-24 UNF	UNF	9.525 mm	24 TPI · 1.058 mm	Q8.433 mm	—
7/16-20 UNF	UNF	11.113 mm	20 TPI · 1.27 mm	25/649.922 mm	—
1/2-20 UNF	UNF	12.7 mm	20 TPI · 1.27 mm	29/6411.509 mm	—
9/16-18 UNF	UNF	14.288 mm	18 TPI · 1.411 mm	33/6413.097 mm	—
5/8-18 UNF	UNF	15.875 mm	18 TPI · 1.411 mm	37/6414.684 mm	—
3/4-16 UNF	UNF	19.05 mm	16 TPI · 1.588 mm	11/1617.463 mm	—
7/8-14 UNF	UNF	22.225 mm	14 TPI · 1.814 mm	13/1620.638 mm	—
1-12 UNF	UNF	25.4 mm	12 TPI · 2.117 mm	59/6423.416 mm	—
1/4-32 UNEF	UNEF	6.35 mm	32 TPI · 0.794 mm	5.6 mm5.6 mm	—
5/16-32 UNEF	UNEF	7.938 mm	32 TPI · 0.794 mm	7.1 mm7.1 mm	—
3/8-32 UNEF	UNEF	9.525 mm	32 TPI · 0.794 mm	8.7 mm8.7 mm	—
7/16-28 UNEF	UNEF	11.113 mm	28 TPI · 0.907 mm	10.2 mm10.2 mm	—
1/2-28 UNEF	UNEF	12.7 mm	28 TPI · 0.907 mm	11.8 mm11.8 mm	—
9/16-24 UNEF	UNEF	14.288 mm	24 TPI · 1.058 mm	13.2 mm13.2 mm	—
5/8-24 UNEF	UNEF	15.875 mm	24 TPI · 1.058 mm	14.8 mm14.8 mm	—
3/4-20 UNEF	UNEF	19.05 mm	20 TPI · 1.27 mm	17.8 mm17.8 mm	—
7/8-20 UNEF	UNEF	22.225 mm	20 TPI · 1.27 mm	21 mm21 mm	—
1-20 UNEF	UNEF	25.4 mm	20 TPI · 1.27 mm	24.1 mm24.1 mm	—
1/8-40 BSW	BSW	3.175 mm	40 TPI · 0.635 mm	2.5 mm2.5 mm	—
5/32-32 BSW	BSW	3.969 mm	32 TPI · 0.794 mm	3.1 mm3.1 mm	—
3/16-24 BSW	BSW	4.763 mm	24 TPI · 1.058 mm	3.6 mm3.6 mm	—
7/32-24 BSW	BSW	5.556 mm	24 TPI · 1.058 mm	4.5 mm4.5 mm	—
1/4-20 BSW	BSW	6.35 mm	20 TPI · 1.27 mm	5 mm5 mm	—
5/16-18 BSW	BSW	7.938 mm	18 TPI · 1.411 mm	6.5 mm6.5 mm	—
3/8-16 BSW	BSW	9.525 mm	16 TPI · 1.588 mm	7.9 mm7.9 mm	—
7/16-14 BSW	BSW	11.113 mm	14 TPI · 1.814 mm	9.2 mm9.2 mm	—
1/2-12 BSW	BSW	12.7 mm	12 TPI · 2.117 mm	10.5 mm10.5 mm	—
9/16-12 BSW	BSW	14.288 mm	12 TPI · 2.117 mm	12 mm12 mm	—
5/8-11 BSW	BSW	15.875 mm	11 TPI · 2.309 mm	13.4 mm13.4 mm	—
3/4-10 BSW	BSW	19.05 mm	10 TPI · 2.54 mm	16.4 mm16.4 mm	—
7/8-9 BSW	BSW	22.225 mm	9 TPI · 2.822 mm	19.25 mm19.25 mm	—
1-8 BSW	BSW	25.4 mm	8 TPI · 3.175 mm	22 mm22 mm	—
3/16-32 BSF	BSF	4.763 mm	32 TPI · 0.794 mm	4 mm4 mm	—
7/32-28 BSF	BSF	5.556 mm	28 TPI · 0.907 mm	4.6 mm4.6 mm	—
1/4-26 BSF	BSF	6.35 mm	26 TPI · 0.977 mm	5.3 mm5.3 mm	—
5/16-22 BSF	BSF	7.938 mm	22 TPI · 1.155 mm	6.7 mm6.7 mm	—
3/8-20 BSF	BSF	9.525 mm	20 TPI · 1.27 mm	8.2 mm8.2 mm	—
7/16-18 BSF	BSF	11.113 mm	18 TPI · 1.411 mm	9.6 mm9.6 mm	—
1/2-16 BSF	BSF	12.7 mm	16 TPI · 1.588 mm	11 mm11 mm	—
9/16-16 BSF	BSF	14.288 mm	16 TPI · 1.588 mm	12.6 mm12.6 mm	—
5/8-14 BSF	BSF	15.875 mm	14 TPI · 1.814 mm	14 mm14 mm	—
3/4-12 BSF	BSF	19.05 mm	12 TPI · 2.117 mm	16.8 mm16.8 mm	—
7/8-11 BSF	BSF	22.225 mm	11 TPI · 2.309 mm	19.75 mm19.75 mm	—
1-10 BSF	BSF	25.4 mm	10 TPI · 2.54 mm	22.75 mm22.75 mm	—
G 1/16 BSPPNominal 1/16 in	BSPP / G — Parallel	7.723 mm	28 TPI · 0.907 mm	6.8 mm6.8 mm	—
G 1/8 BSPPNominal 1/8 in	BSPP / G — Parallel	9.728 mm	28 TPI · 0.907 mm	8.8 mm8.8 mm	—
G 1/4 BSPPNominal 1/4 in	BSPP / G — Parallel	13.157 mm	19 TPI · 1.337 mm	11.8 mm11.8 mm	—
G 3/8 BSPPNominal 3/8 in	BSPP / G — Parallel	16.662 mm	19 TPI · 1.337 mm	15.25 mm15.25 mm	—
G 1/2 BSPPNominal 1/2 in	BSPP / G — Parallel	20.955 mm	14 TPI · 1.814 mm	19 mm19 mm	—
G 5/8 BSPPNominal 5/8 in	BSPP / G — Parallel	22.911 mm	14 TPI · 1.814 mm	21 mm21 mm	—
G 3/4 BSPPNominal 3/4 in	BSPP / G — Parallel	26.441 mm	14 TPI · 1.814 mm	24.5 mm24.5 mm	—
G 1 BSPPNominal 1 in	BSPP / G — Parallel	33.249 mm	11 TPI · 2.309 mm	30.75 mm30.75 mm	—
G 1 1/4 BSPPNominal 1 1/4 in	BSPP / G — Parallel	41.91 mm	11 TPI · 2.309 mm	39.5 mm39.5 mm	—
G 1 1/2 BSPPNominal 1 1/2 in	BSPP / G — Parallel	47.803 mm	11 TPI · 2.309 mm	45.25 mm45.25 mm	—
G 2 BSPPNominal 2 in	BSPP / G — Parallel	59.614 mm	11 TPI · 2.309 mm	57 mm57 mm	—
Rc 1/16 BSPTNominal 1/16 in	BSPT / Rc — Tapered	7.723 mm	28 TPI · 0.907 mm	6.3 mm6.3 mm	—
Rc 1/8 BSPTNominal 1/8 in	BSPT / Rc — Tapered	9.728 mm	28 TPI · 0.907 mm	8.4 mm8.4 mm	—
Rc 1/4 BSPTNominal 1/4 in	BSPT / Rc — Tapered	13.157 mm	19 TPI · 1.337 mm	10.8 mm10.8 mm	—
Rc 3/8 BSPTNominal 3/8 in	BSPT / Rc — Tapered	16.662 mm	19 TPI · 1.337 mm	14.5 mm14.5 mm	—
Rc 1/2 BSPTNominal 1/2 in	BSPT / Rc — Tapered	20.955 mm	14 TPI · 1.814 mm	18 mm18 mm	—
Rc 5/8 BSPTNominal 5/8 in	BSPT / Rc — Tapered	22.911 mm	14 TPI · 1.814 mm	Awaiting verification	—
Rc 3/4 BSPTNominal 3/4 in	BSPT / Rc — Tapered	26.441 mm	14 TPI · 1.814 mm	23 mm23 mm	—
Rc 1 BSPTNominal 1 in	BSPT / Rc — Tapered	33.249 mm	11 TPI · 2.309 mm	29 mm29 mm	—
Rc 1 1/4 BSPTNominal 1 1/4 in	BSPT / Rc — Tapered	41.91 mm	11 TPI · 2.309 mm	38 mm38 mm	—
Rc 1 1/2 BSPTNominal 1 1/2 in	BSPT / Rc — Tapered	47.803 mm	11 TPI · 2.309 mm	44 mm44 mm	—
Rc 2 BSPTNominal 2 in	BSPT / Rc — Tapered	59.614 mm	11 TPI · 2.309 mm	55 mm55 mm	—
1/8-27 NPTNominal 1/8 in	NPT — Tapered pipe thread	10.389 mm	27 TPI · 0.941 mm	21/648.334 mm	—
1/4-18 NPTNominal 1/4 in	NPT — Tapered pipe thread	13.741 mm	18 TPI · 1.411 mm	7/1611.113 mm	—
3/8-18 NPTNominal 3/8 in	NPT — Tapered pipe thread	17.221 mm	18 TPI · 1.411 mm	9/1614.288 mm	—
1/2-14 NPTNominal 1/2 in	NPT — Tapered pipe thread	21.438 mm	14 TPI · 1.814 mm	45/6417.859 mm	—
3/4-14 NPTNominal 3/4 in	NPT — Tapered pipe thread	26.772 mm	14 TPI · 1.814 mm	29/3223.019 mm	—
1-11.5 NPTNominal 1 in	NPT — Tapered pipe thread	33.477 mm	11.5 TPI · 2.209 mm	1 9/6428.972 mm	—
1 1/4-11.5 NPTNominal 1 1/4 in	NPT — Tapered pipe thread	42.24 mm	11.5 TPI · 2.209 mm	1 31/6437.703 mm	—
1 1/2-11.5 NPTNominal 1 1/2 in	NPT — Tapered pipe thread	48.311 mm	11.5 TPI · 2.209 mm	1 47/6444.053 mm	—
2-11.5 NPTNominal 2 in	NPT — Tapered pipe thread	60.35 mm	11.5 TPI · 2.209 mm	2 13/6455.959 mm	—

DATA & SAFE USE

Verified before displayed.

141 thread entries are held in a separate structured dataset so dimensions, sources and future fields can be reviewed without rewriting the interface.

01 · TAPPING DRILLS

Recommendation, not guesswork.

Thread standards define the thread geometry. The displayed tapping drills come from established tap and drill manufacturers and remain identified as workshop recommendations.

02 · CLEARANCE HOLES

Kept separate.

Close, normal and loose metric clearance holes use the ISO 273 series. They never replace the tapping drill. Unverified clearance series are left unavailable.

03 · PIPE THREADS

Nominal is not actual.

BSP and NPT nominal pipe sizes are shown separately from the real reference diameter. BSPP is parallel; BSPT and NPT are tapered and stay clearly distinguished.

04 · CUSTOM ENGAGEMENT

Secondary by design.

The optional calculation is limited to straight 60° cut threads. It is disabled for Whitworth-form and tapered pipe threads where the simple approximation is unsuitable.

Primary standards & technical references

Use the links below to review the standard scope and manufacturer drill guidance behind the published values.

Workshop reference

Starting values only. Confirm critical, pressure-retaining, safety-related or close-tolerance work against the current thread standard, the specific tap manufacturer, material, hole depth and gauging requirements.

Back to Toolbox →