M8 Low Head Socket Cap Screw, DIN 7984

Driven with a 5 mm hex key, the M8 low head socket cap screw (DIN 7984) has a head 12.73 to 13 mm across and 4.82 to 5 mm tall. Its M8 × 1.25 thread comes in 14 lengths from 16 to 100 mm, each as simplified and threaded STEP.

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

• Also searched as: M8 bolt, M8 x 16 to M8 x 100 bolts
• Model id: din7984-m8
• Standard: DIN 7984:2022 · thread M8 × 1.25, ISO metric coarse, right hand

Lengths

Length (mm)	Part key	Simplified	Threaded
16	din7984-m8x16	STEP	STEP
20	din7984-m8x20	STEP	STEP
25	din7984-m8x25	STEP	STEP
30	din7984-m8x30	STEP	STEP
35	din7984-m8x35	STEP	STEP
40	din7984-m8x40	STEP	STEP
45	din7984-m8x45	STEP	STEP
50	din7984-m8x50	STEP	STEP
55	din7984-m8x55	STEP	STEP
60	din7984-m8x60	STEP	STEP
70	din7984-m8x70	STEP	STEP
80	din7984-m8x80	STEP	STEP
90	din7984-m8x90	STEP	STEP
100	din7984-m8x100	STEP	STEP

Dimensions

Symbol	Name	min	nom	max	Modeled	Rule	Level
P	Thread pitch		1.25		1.25	nominal	L1
b	Thread length, l up to 125		22 ref		22	reference value	L1
b2	Thread length, l over 125 up to 200		28 ref		28	reference value	L1
da	Transition diameter			9.2	9.2	single limit (max), modeled at the limit	L1
dk	Head diameter	12.73		13	12.865	midpoint of min–max	L1
ds	Shank diameter	7.78		8	7.89	midpoint of min–max	L1
dw	Bearing face diameter	12.03			12.03	single limit (min), modeled at the limit	L0 (min: one source)
e	Socket width across corners	5.72			5.72	single limit (min), modeled at the limit	L1
k	Head height	4.82		5	4.91	midpoint of min–max	L1
lf	Underhead fillet length			1.02	1.02	single limit (max), modeled at the limit	L1
r	Underhead fillet radius	0.4		0.6	0.5	midpoint of min–max	L0 (max: one source)
s	Socket width across flats	5.02	5	5.14	5.08	midpoint of min–max	L1
t	Socket depth	3.65	3.8	3.95	3.8	nominal	L1
v	Head top chamfer or radius			0.8	0.8	single limit (max), modeled at the limit	L0 (max: one source)
P	Coarse thread pitch		1.25		1.25	nominal	L1
tap_drill	Tap drill diameter		6.75		6.75	nominal	L1
d1	Basic minor diameter		6.646835		6.646835	nominal	L1
ch_angle	Chamfered end angle			50	50	single limit (max), modeled at the limit	L2
dh_fine	Clearance hole, fine series		8.4		8.4	nominal	L1
dh_medium	Clearance hole, medium series		9		9	nominal	L1
dh_coarse	Clearance hole, coarse series		10		10	nominal	L1

Thread and holes

• Tap drill: 6.75 mm (method: d − P), L1, sources amesweb-tap-drill, rule-tap-drill.
• Clearance hole (ISO 273): close 8.4, normal 9, loose 10 mm (L1: fine, medium and coarse series (albany-clearance, wikipedia-de-clearance)).

Drawing

As a PDF: CC-DIN7984-SZ-M8.pdf.

Goes with the M8 low head socket cap screw

• Hex key: 5 mm, the socket's nominal width across flats (s) in the table above.
• ISO 4032 hex nut, the same size as this M8 low head socket cap screw: M8 Hex Nut (Hexagon Nut), ISO 4032 / DIN 934
• ISO 7089 flat washer, the same size as this M8 low head socket cap screw: M8 Flat Washer (Plain Washer), ISO 7089

The M8 low head socket cap screw beside the M6

The M8 is the largest of the 5 DIN 7984 low head socket cap screws published here, from M3 to M8.

• Thread pitch (P): 1.25 mm on the M8 low head socket cap screw, against 1 mm on the M6.
• Thread length, l up to 125 (b): 22 mm (reference) on the M8 low head socket cap screw, against 18 mm (reference) on the M6.
• Transition diameter (da): up to 9.2 mm on the M8 low head socket cap screw, against up to 6.8 mm on the M6.
• Head diameter (dk): 12.73 to 13 mm on the M8 low head socket cap screw, against 9.78 to 10 mm on the M6.
• Shank diameter (ds): 7.78 to 8 mm on the M8 low head socket cap screw, against 5.82 to 6 mm on the M6.
• Bearing face diameter (dw): at least 12.03 mm on the M8 low head socket cap screw, against at least 9.2 mm on the M6.
• Socket width across corners (e): at least 5.72 mm on the M8 low head socket cap screw, against at least 4.58 mm on the M6.

Other sizes

• One size smaller: M6 Low Head Socket Cap Screw, DIN 7984, 9.78 to 10 mm head, 4 mm hex key.

Documents

• CC-DIN7984-DS-M8.pdf: M8 datasheet: values with levels, lengths, sources
• CC-DIN7984-SZ-M8.pdf: M8 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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