Tap drill and metric thread dimensions

Coarse-pitch metric threads

Thread	P	Choice	d2	D1	D1 max (6H)	Drill	As (mm²)
M1	0.25	1†	0.838	0.729	—	0.75	0.460
M1.2	0.25	1†	1.038	0.929	—	0.95	0.732
M1.6	0.35	1	1.373	1.221	—	1.25	1.27
M2	0.4	1	1.740	1.567	—	1.60	2.07
M2.5	0.45	1	2.208	2.013	—	2.05	3.39
M3	0.5	1	2.675	2.459	2.599	2.50	5.03
M4	0.7	1	3.545	3.242	3.422	3.30	8.78
M5	0.8	1	4.480	4.134	4.334	4.20	14.2
M6	1	1	5.350	4.917	5.153	5.00	20.1
M8	1.25	1	7.188	6.647	6.912	6.80	36.6
M10	1.5	1	9.026	8.376	8.676	8.50	58.0
M12	1.75	1	10.863	10.106	10.441	10.20	84.3
M14	2	2	12.701	11.835	12.210	12.00	115
M16	2	1	14.701	13.835	14.210	14.00	157
M18	2.5	2	16.376	15.294	15.744	15.50	192
M20	2.5	1	18.376	17.294	17.744	17.50	245
M22	2.5	2	20.376	19.294	19.744	19.50	303
M24	3	1	22.051	20.752	21.252	21.00	353
M27	3	2†	25.051	23.752	24.252	24.00	459
M30	3.5	1	27.727	26.211	26.771	26.50	561
M33	3.5	2†	30.727	29.211	29.771	29.50	694
M36	4	1	33.402	31.670	32.270	32.00	817
M39	4	2†	36.402	34.670	35.270	35.00	976
M42	4.5	1	39.077	37.129	—	37.50	1120
M45	4.5	2†	42.077	40.129	—	40.50	1310
M48	5	1	44.752	42.587	—	43.00	1470
M52	5	2†	48.752	46.587	—	47.00	1760
M56	5.5	1	52.428	50.046	—	50.50	2030
M60	5.5	2	56.428	54.046	—	54.50†	2360
M64	6	1	60.103	57.505	—	58.00	2680

1 = first choice, 2 = second choice (ISO 261). † confirmed by one source only.

Selected fine-pitch sizes (ISO 262)

Thread	d2	D1	D1 max (6H)	Drill	As (mm²)
M8×1	7.350	6.917	7.153	7.00	39.2
M10×1.25	9.188	8.647	8.912	8.80	61.2
M10×1	9.350	8.917	9.153	9.00	64.5
M12×1.5	11.026	10.376	10.676	10.50	88.1
M12×1.25	11.188	10.647	10.912	10.80	92.1
M14×1.5	13.026	12.376	12.676	12.50	125
M16×1.5	15.026	14.376	14.676	14.50	167
M18×2	16.701	15.835	16.210	16.00*	204
M18×1.5	17.026	16.376	16.676	16.50	216
M20×2	18.701	17.835	18.210	18.00	258
M20×1.5	19.026	18.376	18.676	18.50	272
M22×2	20.701	19.835	20.210	20.00	318
M22×1.5	21.026	20.376	20.676	20.50	333
M24×2	22.701	21.835	22.210	22.00	384
M27×2	25.701	24.835	25.210	25.00	496
M30×2	28.701	27.835	28.210	28.00	621
M33×2	31.701	30.835	31.210	31.00	761
M36×3	34.051	32.752	33.252	33.00†	865
M39×3	37.051	35.752	36.252	36.00†	1030
M42×3	40.051	38.752	39.252	39.00†	1210
M45×3	43.051	41.752	42.252	42.00*	1400
M48×3	46.051	44.752	45.252	45.00†	1600
M52×4	49.402	47.670	48.270	48.00*	1830
M56×4	53.402	51.670	52.270	52.00†	2140
M60×4	57.402	55.670	56.270	56.00*	2480
M64×4	61.402	59.670	60.270	60.00†	2850

Drill: unmarked values are from Gühring's DIN 336 table and agree with Engineering Toolbox. † Engineering Toolbox only. * no published value found; computed as d − P.

Notes

Drill sizes are for cutting taps. DIN 336 explicitly does not apply to cold-forming taps; a forming tap needs a larger hole, and published recommendations differ between makers.
The principle of ISO 2306: within the tolerance, the larger the hole, the more economical the tapping. The rule d − P gives a hole inside the 6H tolerance: for M3 to M39 the standard drills sit between 28 % and 58 % of the band, most of them below its middle.
The 6H limits come from the minor-diameter tolerance of ISO 965-1, which depends only on the pitch; this tool shows limits only for pitches whose tolerance was confirmed from published 6H tables.
Values are basic sizes at 20 °C. ISO 724 rounds dimensions to three decimals; stress areas are given to three significant figures, as in ISO 898-1.
The fine-pitch list follows the selected sizes of ISO 262:1998; the table of the 2023 edition could not be checked.

Coarse-pitch metric threads

Selected fine-pitch sizes (ISO 262)

Formulae

Notes