M4 Socket Head Cap Screw (Allen Bolt), ISO 4762 / DIN 912

An M4 socket head cap screw (ISO 4762) has a head 6.78 to 7 mm across and 3.82 to 4 mm tall, driven with a 3 mm hex key. This page has 10 lengths from 6 to 40 mm, each as simplified and threaded STEP.

How these parts are made, and what the levels mean: read the method

• Also searched as: M4 bolt, M4 x 6 to M4 x 40 bolts
• Equivalent standards: DIN 912 (as listed by fasteners.eu); the values here are ISO 4762's.
• Model id: iso4762-m4
• Standard: ISO 4762:2004 · thread M4 × 0.7, ISO metric coarse, right hand

Lengths

Length (mm)	Part key	Simplified	Threaded
6	iso4762-m4x6	STEP	STEP
8	iso4762-m4x8	STEP	STEP
10	iso4762-m4x10	STEP	STEP
12	iso4762-m4x12	STEP	STEP
16	iso4762-m4x16	STEP	STEP
20	iso4762-m4x20	STEP	STEP
25	iso4762-m4x25	STEP	STEP
30	iso4762-m4x30	STEP	STEP
35	iso4762-m4x35	STEP	STEP
40	iso4762-m4x40	STEP	STEP

Dimensions

Symbol	Name	min	nom	max	Modeled	Rule	Level
P	Thread pitch		0.7		0.7	nominal	L1
b	Thread length	20	20 ref		20	reference value	L1
dk	Head diameter, plain head	6.78		7	6.89	midpoint of min–max	L1
dk_knurled	Head diameter, knurled head			7.22	7.22	single limit (max), modeled at the limit	L1
da	Transition diameter			4.7	4.7	single limit (max), modeled at the limit	L1
ds	Shank diameter	3.82		4	3.91	midpoint of min–max	L1
e	Socket width across corners	3.443			3.443	single limit (min), modeled at the limit	L1
k	Head height	3.82		4	3.91	midpoint of min–max	L1
r	Underhead fillet radius	0.2		0.35	0.275	midpoint of min–max	L0 (max: one source)
s	Socket width across flats	3.02	3	3.08	3.05	midpoint of min–max	L1
t	Socket depth	2			2	single limit (min), modeled at the limit	L1
lf	Underhead fillet length			0.6	0.6	single limit (max), modeled at the limit	L0 (max: one source)
v	Head top chamfer or radius			0.4	0.4	single limit (max), modeled at the limit	L1
dw	Bearing face diameter	6.53			6.53	single limit (min), modeled at the limit	L1
w	Wall thickness	1.4			1.4	single limit (min), modeled at the limit	L1
P	Coarse thread pitch		0.7		0.7	nominal	L1
tap_drill	Tap drill diameter		3.3		3.3	nominal	L1
d1	Basic minor diameter		3.2422276		3.2422276	nominal	L1
ch_angle	Chamfered end angle			50	50	single limit (max), modeled at the limit	L2
dh_fine	Clearance hole, fine series		4.3		4.3	nominal	L1
dh_medium	Clearance hole, medium series		4.5		4.5	nominal	L1
dh_coarse	Clearance hole, coarse series		4.8		4.8	nominal	L1

Thread and holes

• Tap drill: 3.3 mm (method: d − P), L1, sources amesweb-tap-drill, rule-tap-drill.
• Clearance hole (ISO 273): close 4.3, normal 4.5, loose 4.8 mm (L1: fine, medium and coarse series (albany-clearance, wikipedia-de-clearance)).

Drawing

As a PDF: CC-ISO4762-SZ-M4.pdf.

Goes with the M4 socket head cap screw

• Hex key: 3 mm, the socket's nominal width across flats (s) in the table above.
• ISO 4032 hex nut, the same size as this M4 socket head cap screw: M4 Hex Nut (Hexagon Nut), ISO 4032 / DIN 934
• ISO 7089 flat washer, the same size as this M4 socket head cap screw: M4 Flat Washer (Plain Washer), ISO 7089

Approximate mass

Approximate mass of 1000 screws by length, from fasten.it's DIN EN ISO 4762 mass table (fasten-it-iso4762), which it captions “Approximate mass, in kg x1000 pcs, (ρ=7,85 kg/dm3)”.

Length l (mm)	mass per 1000 (kg)
6	1.5
8	1.65
10	1.8
12	1.95
16	2.25
20	2.65
25	3.15
30	3.65
35	4.15
40	4.65

The M4 socket head cap screw beside the M3 and the M5

The M4 is number 4, counting from the smallest, of the 7 ISO 4762 socket head cap screws published here, from M2 to M8.

• Thread pitch (P): 0.7 mm on the M4 socket head cap screw, against 0.5 mm on the M3 and 0.8 mm on the M5.
• Thread length (b): at least 20 mm on the M4 socket head cap screw, against at least 18 mm on the M3 and at least 22 mm on the M5.
• Head diameter, plain head (dk): 6.78 to 7 mm on the M4 socket head cap screw, against 5.32 to 5.5 mm on the M3 and 8.28 to 8.5 mm on the M5.
• Head diameter, knurled head (dk_knurled): up to 7.22 mm on the M4 socket head cap screw, against up to 5.68 mm on the M3 and up to 8.72 mm on the M5.
• Transition diameter (da): up to 4.7 mm on the M4 socket head cap screw, against up to 3.6 mm on the M3 and up to 5.7 mm on the M5.
• Shank diameter (ds): 3.82 to 4 mm on the M4 socket head cap screw, against 2.86 to 3 mm on the M3 and 4.82 to 5 mm on the M5.
• Socket width across corners (e): at least 3.443 mm on the M4 socket head cap screw, against at least 2.873 mm on the M3 and at least 4.583 mm on the M5.
• Head height (k): 3.82 to 4 mm on the M4 socket head cap screw, against 2.86 to 3 mm on the M3 and 4.82 to 5 mm on the M5.

Other sizes

• One size smaller: M3 Socket Head Cap Screw (Allen Bolt), ISO 4762 / DIN 912, 5.32 to 5.5 mm head, 2.5 mm hex key.
• One size larger: M5 Socket Head Cap Screw (Allen Bolt), ISO 4762 / DIN 912, 8.28 to 8.5 mm head, 4 mm hex key.

Documents

• CC-ISO4762-DS-M4.pdf: M4 datasheet: values with levels, lengths, sources
• CC-ISO4762-SZ-M4.pdf: M4 drawing: this size's values on the views
• parts.json: the part record of every length (the platform contract)

Sources

albany-clearance, amesweb-iso4762, amesweb-iso4762-lengths, amesweb-tap-drill, fasten-it-iso4762, fasteners-eu-iso4762, fasteners-eu-iso4762-lengths, iso4753-2011-sample, opac-iso4762, rule-basic-minor, rule-tap-drill, wikipedia-de-clearance, wikipedia-iso261. Full citations: the method page and this size's datasheet.

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