M4 Low Head Socket Cap Screw, DIN 7984

Driven with a 2.5 mm hex key, the M4 low head socket cap screw (DIN 7984) has a head 6.78 to 7 mm across and 2.66 to 2.8 mm tall. Its M4 × 0.7 thread comes in 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
• Model id: din7984-m4
• Standard: DIN 7984:2022 · thread M4 × 0.7, ISO metric coarse, right hand

Lengths

Length (mm)	Part key	Simplified	Threaded
6	din7984-m4x6	STEP	STEP
8	din7984-m4x8	STEP	STEP
10	din7984-m4x10	STEP	STEP
12	din7984-m4x12	STEP	STEP
16	din7984-m4x16	STEP	STEP
20	din7984-m4x20	STEP	STEP
25	din7984-m4x25	STEP	STEP
30	din7984-m4x30	STEP	STEP
35	din7984-m4x35	STEP	STEP
40	din7984-m4x40	STEP	STEP

Dimensions

Symbol	Name	min	nom	max	Modeled	Rule	Level
P	Thread pitch		0.7		0.7	nominal	L1
b	Thread length, l up to 125		14 ref		14	reference value	L1
da	Transition diameter			4.7	4.7	single limit (max), modeled at the limit	L1
dk	Head diameter	6.78		7	6.89	midpoint of min–max	L1
ds	Shank diameter	3.82		4	3.91	midpoint of min–max	L1
dw	Bearing face diameter	6.2			6.2	single limit (min), modeled at the limit	L0 (min: one source)
e	Socket width across corners	2.87			2.87	single limit (min), modeled at the limit	L1
k	Head height	2.66		2.8	2.73	midpoint of min–max	L1
lf	Underhead fillet length			0.6	0.6	single limit (max), modeled at the limit	L1
r	Underhead fillet radius	0.2		0.35	0.275	midpoint of min–max	L0 (max: one source)
s	Socket width across flats	2.52	2.5	2.6	2.56	midpoint of min–max	L1
t	Socket depth	2.18	2.3	2.42	2.3	nominal	L1
v	Head top chamfer or radius			0.4	0.4	single limit (max), modeled at the limit	L0 (max: one source)
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-DIN7984-SZ-M4.pdf.

Goes with the M4 low head socket cap screw

• Hex key: 2.5 mm, the socket's nominal width across flats (s) in the table above.
• ISO 4032 hex nut, the same size as this M4 low head socket cap screw: M4 Hex Nut (Hexagon Nut), ISO 4032 / DIN 934
• ISO 7089 flat washer, the same size as this M4 low head socket cap screw: M4 Flat Washer (Plain Washer), ISO 7089

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

The M4 is number 2, counting from the smallest, of the 5 DIN 7984 low head socket cap screws published here, from M3 to M8.

• Thread pitch (P): 0.7 mm on the M4 low head socket cap screw, against 0.5 mm on the M3 and 0.8 mm on the M5.
• Thread length, l up to 125 (b): 14 mm (reference) on the M4 low head socket cap screw, against 12 mm (reference) on the M3 and 16 mm (reference) on the M5.
• Transition diameter (da): up to 4.7 mm on the M4 low head socket cap screw, against up to 3.6 mm on the M3 and up to 5.7 mm on the M5.
• Head diameter (dk): 6.78 to 7 mm on the M4 low head socket cap screw, against 5.32 to 5.5 mm on the M3 and 8.28 to 8.5 mm on the M5.
• Shank diameter (ds): 3.82 to 4 mm on the M4 low head socket cap screw, against 2.86 to 3 mm on the M3 and 4.82 to 5 mm on the M5.
• Bearing face diameter (dw): at least 6.2 mm on the M4 low head socket cap screw, against at least 4.84 mm on the M3 and at least 7.7 mm on the M5.
• Socket width across corners (e): at least 2.87 mm on the M4 low head socket cap screw, against at least 2.3 mm on the M3 and at least 3.44 mm on the M5.
• Head height (k): 2.66 to 2.8 mm on the M4 low head socket cap screw, against 1.86 to 2 mm on the M3 and 3.32 to 3.5 mm on the M5.

Other sizes

• One size smaller: M3 Low Head Socket Cap Screw, DIN 7984, 5.32 to 5.5 mm head, 2 mm hex key.
• One size larger: M5 Low Head Socket Cap Screw, DIN 7984, 8.28 to 8.5 mm head, 3 mm hex key.

Documents

• CC-DIN7984-DS-M4.pdf: M4 datasheet: values with levels, lengths, sources
• CC-DIN7984-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-tap-drill, aspen-din7984, aspen-din7984-pages, fasten-it-din7984, fasteners-eu-din7984, fasteners-eu-din7984-lengths, globalfastener-din7984, iso4753-2011-sample, rule-basic-minor, rule-din7984-lg, rule-tap-drill, wikipedia-de-clearance, wikipedia-iso261. Full citations: the method page and this size's datasheet.

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