Fasteners (bolts, nuts, studs) · Size & tolerance table

Metric coarse threads, hexagon bolt and nut sizes and spanner widths (ISO 4014 / 4017 / 4032)

Standard: ISO 261 / ISO 262 · ISO 4014 · ISO 4017 · ISO 4032 · ISO 898-1 · ISO 273 formerly DIN 931, DIN 933, DIN 934

The everyday dimensions of an ISO metric hexagon bolt, screw and nut with coarse thread. DIN 931 (partly threaded bolt), DIN 933 (fully threaded screw) and DIN 934 (nut) were withdrawn in favour of ISO 4014, ISO 4017 and ISO 4032, which are the same in all sizes except four: the ISO width across flats is smaller for M10, M12, M14 and M22. A DIN spanner does not fit those ISO heads.

The tensile stress area As is what the proof load and breaking load in ISO 898-1 are calculated on: load = As × the stress for the property class (for example 8.8: proof stress 580 N/mm² up to M16 and 600 N/mm² above).

Metric coarse thread — hexagon bolts, screws and nuts

Thread			Width across flats		Heights		Holes
Size	P mm	As mm²	s ISO mm	s DIN mm	m mm	k mm	Clearance mm	Tap drill mm
M3	0.5	5.03	5.5	5.5	2.4	2	3.4	2.5
M4	0.7	8.78	7	7	3.2	2.8	4.5	3.3
M5	0.8	14.2	8	8	4.7	3.5	5.5	4.2
M6	1	20.1	10	10	5.2	4	6.6	5
M8	1.25	36.6	13	13	6.8	5.3	9	6.8
M10	1.5	58.0	16	17	8.4	6.4	11	8.5
M12	1.75	84.3	18	19	10.8	7.5	13.5	10.2
M14	2	115	21	22	12.8	8.8	15.5	12
M16	2	157	24	24	14.8	10	17.5	14
M20	2.5	245	30	30	18	12.5	22	17.5
M22	2.5	303	34	32	19.4	14	24	19.5
M24	3	353	36	36	21.5	15	26	21
M27	3	459	41	41	23.8	17	30	24
M30	3.5	561	46	46	25.6	18.7	33	26.5
M33	3.5	694	50	50	28.7	21	36	29.5
M36	4	817	55	55	31	22.5	39	32
M42	4.5	1120	65	65	34	26	45	37.5
M48	5	1470	75	75	38	30	52	43
M56	5.5	2030	85	85	45	35	62	50.5
M64	6	2680	95	95	51	40	70	58

Notes

M14, M22, M27 and M33 are second-choice sizes; prefer M12, M16, M20, M24, M30 and M36 where there is a choice.
Structural bolting assemblies to EN 14399 (HR and HV) have larger heads and nuts than ISO 4014 / 4032 — for example s = 22 mm for M12, 27 mm for M16 and 32 mm for M20 — so they need their own spanners.
The stress area is calculated from the pitch and mean of the pitch and minor diameters, As = π/4 × ((d2 + d3)/2)²; every value above was recalculated and agrees with ISO 898-1.
Tapping drill sizes are the usual d − P for about 75% thread engagement.