Tap Drill Chart

Inputs

Thread size

Cutting-Tap Drill Chart (67 Sizes)

Filter by size or series. Drill millimetres are source-table values; inches are converted. Only listed sizes are supported.

Filter chart

Cutting-Tap Drill Chart (67 Sizes)
Thread size	Series	Pitch / TPI	Drill mm	Drill in (converted)
M3 × 0.5	Metric coarse	0.5 mm	2.5	0.0984252
M4 × 0.7	Metric coarse	0.7 mm	3.3	0.12992126
M5 × 0.8	Metric coarse	0.8 mm	4.2	0.16535433
M6 × 1	Metric coarse	1 mm	5	0.19685039
M8 × 1.25	Metric coarse	1.25 mm	6.8	0.26771654
M10 × 1.5	Metric coarse	1.5 mm	8.5	0.33464567
M12 × 1.75	Metric coarse	1.75 mm	10.2	0.4015748
M14 × 2	Metric coarse	2 mm	12	0.47244094
M16 × 2	Metric coarse	2 mm	14	0.5511811
M18 × 2.5	Metric coarse	2.5 mm	15.5	0.61023622
M20 × 2.5	Metric coarse	2.5 mm	17.5	0.68897638
M22 × 2.5	Metric coarse	2.5 mm	19.5	0.76771654
M24 × 3	Metric coarse	3 mm	21	0.82677165
M27 × 3	Metric coarse	3 mm	24	0.94488189
M30 × 3.5	Metric coarse	3.5 mm	26.5	1.04330709
M3 × 0.35	Metric fine	0.35 mm	2.65	0.10433071
M4 × 0.5	Metric fine	0.5 mm	3.5	0.13779528
M5 × 0.5	Metric fine	0.5 mm	4.5	0.17716535
M6 × 0.75	Metric fine	0.75 mm	5.2	0.20472441
M8 × 0.75	Metric fine	0.75 mm	7.2	0.28346457
M8 × 1	Metric fine	1 mm	7	0.27559055
M10 × 0.75	Metric fine	0.75 mm	9.2	0.36220472
M10 × 1	Metric fine	1 mm	9	0.35433071
M10 × 1.25	Metric fine	1.25 mm	8.8	0.34645669
M12 × 1	Metric fine	1 mm	11	0.43307087
M12 × 1.25	Metric fine	1.25 mm	10.8	0.42519685
M12 × 1.5	Metric fine	1.5 mm	10.5	0.41338583
M14 × 1.5	Metric fine	1.5 mm	12.5	0.49212598
M16 × 1	Metric fine	1 mm	15	0.59055118
M16 × 1.5	Metric fine	1.5 mm	14.5	0.57086614
M18 × 1.5	Metric fine	1.5 mm	16.5	0.6496063
M20 × 1.5	Metric fine	1.5 mm	18.5	0.72834646
M24 × 2	Metric fine	2 mm	22	0.86614173
#1-64 UNC	UNC coarse	64 TPI	1.55	0.06102362
#2-56 UNC	UNC coarse	56 TPI	1.85	0.07283465
#4-40 UNC	UNC coarse	40 TPI	2.35	0.09251969
#6-32 UNC	UNC coarse	32 TPI	2.85	0.11220472
#8-32 UNC	UNC coarse	32 TPI	3.5	0.13779528
#10-24 UNC	UNC coarse	24 TPI	3.9	0.15354331
#12-24 UNC	UNC coarse	24 TPI	4.5	0.17716535
1/4-20 UNC	UNC coarse	20 TPI	5.1	0.2007874
5/16-18 UNC	UNC coarse	18 TPI	6.6	0.25984252
3/8-16 UNC	UNC coarse	16 TPI	8	0.31496063
7/16-14 UNC	UNC coarse	14 TPI	9.4	0.37007874
1/2-13 UNC	UNC coarse	13 TPI	10.8	0.42519685
9/16-12 UNC	UNC coarse	12 TPI	12.2	0.48031496
5/8-11 UNC	UNC coarse	11 TPI	13.5	0.53149606
3/4-10 UNC	UNC coarse	10 TPI	16.5	0.6496063
7/8-9 UNC	UNC coarse	9 TPI	19.5	0.76771654
1-8 UNC	UNC coarse	8 TPI	22.25	0.87598425
#1-72 UNF	UNF fine	72 TPI	1.55	0.06102362
#2-64 UNF	UNF fine	64 TPI	1.85	0.07283465
#4-48 UNF	UNF fine	48 TPI	2.4	0.09448819
#6-40 UNF	UNF fine	40 TPI	2.95	0.11614173
#8-36 UNF	UNF fine	36 TPI	3.5	0.13779528
#10-32 UNF	UNF fine	32 TPI	4.1	0.16141732
#12-28 UNF	UNF fine	28 TPI	4.6	0.18110236
1/4-28 UNF	UNF fine	28 TPI	5.5	0.21653543
5/16-24 UNF	UNF fine	24 TPI	6.9	0.27165354
3/8-24 UNF	UNF fine	24 TPI	8.5	0.33464567
7/16-20 UNF	UNF fine	20 TPI	9.9	0.38976378
1/2-20 UNF	UNF fine	20 TPI	11.5	0.45275591
9/16-18 UNF	UNF fine	18 TPI	12.9	0.50787402
5/8-18 UNF	UNF fine	18 TPI	14.5	0.57086614
3/4-16 UNF	UNF fine	16 TPI	17.5	0.68897638
7/8-14 UNF	UNF fine	14 TPI	20.4	0.80314961
1-12 UNF	UNF fine	12 TPI	23.25	0.91535433

Formula and method

Drill diameters are exact lookups from Guhring’s “Tapping size holes for thread cutting”, printed pages 471–472, not recommendations generated by nominal diameter minus pitch. Inches = the tabulated millimetres ÷ 25.4.

Worked example

Select M6×1: the table gives 5.00 mm, about 0.19685 in. M6×0.75 gives 5.20 mm and is not replaced with a calculated 5.25 mm.

Assumptions and limits

For cutting taps only. Do not use these sizes for forming/fluteless taps, thread milling or STI wire-insert holes; the source treats those separately.
The source labels metric rows DIN 13 / DIN 336, internal thread 6H, and UNC/UNF rows ASME B1.1, internal thread 2B. It specifies neither a uniform thread percentage for these rows nor material-specific recommendations; this is not an “all 75% thread” chart.
Confirm the hole for the material, required thread percentage, engagement length, tap model/tolerance, blind or through hole, drilling oversize and lubrication. A diameter is not a drill-number recommendation or a guarantee of thread-gauge acceptance.
This chart contains 67 common sizes, checked on 22 October 2026; the source PDF does not state an edition date. Inch values convert the source’s millimetres and do not select the nearest fractional, letter or number drill.

Frequently asked questions

Why do some values differ from diameter minus pitch?

Diameter minus pitch is a common approximation, not a substitute for a specific table. Here M6×0.75 is 5.20 mm and M12×1.75 is 10.20 mm; those source values are retained.

Can I use these sizes with a forming tap?

No. A forming tap displaces material and has different hole-size and tolerance requirements. Use its manufacturer’s table for the material and thread percentage.

Does this chart guarantee strength or gauge acceptance?

No. It supplies traceable starting dimensions. Strength also depends on material, thread percentage and engagement length; verify the finished hole/thread against the drawing and inspection requirements.

References

Tap Drill Chart practical guide and common questions

What does Tap Drill Chart calculate?

Choose a thread to read its cutting-tap drill diameter from Guhring’s public technical table. Filter the chart by size; unlisted sizes are not generated. Drill diameters are exact lookups from Guhring’s “Tapping size holes for thread cutting”, printed pages 471–472, not recommendations generated by nominal diameter minus pitch. Inches = the tabulated millimetres ÷ 25.4.

When is this useful?

Select M6×1: the table gives 5.00 mm, about 0.19685 in. M6×0.75 gives 5.20 mm and is not replaced with a calculated 5.25 mm.

How do I enter the inputs?

Enter the inputs for Tap Drill Chart: Thread size. Calculate, check the units and assumptions, then copy or download the results.

How should I interpret the results?

For cutting taps only. Do not use these sizes for forming/fluteless taps, thread milling or STI wire-insert holes; the source treats those separately. The source labels metric rows DIN 13 / DIN 336, internal thread 6H, and UNC/UNF rows ASME B1.1, internal thread 2B. It specifies neither a uniform thread percentage for these rows nor material-specific recommendations; this is not an “all 75% thread” chart. Confirm the hole for the material, required thread percentage, engagement length, tap model/tolerance, blind or through hole, drilling oversize and lubrication. A diameter is not a drill-number recommendation or a guarantee of thread-gauge acceptance. This chart contains 67 common sizes, checked on 22 October 2026; the source PDF does not state an edition date. Inch values convert the source’s millimetres and do not select the nearest fractional, letter or number drill.

Where are my inputs processed?

Tap Drill Chart runs in this browser. Inputs are not uploaded to a calculation server; copying and CSV download require your action. The existing site analytics and advertising still load.