Question 1

What diameter is an M8 bolt?

Accepted Answer

An M8 bolt has an 8 mm thread diameter. The external measurement across the threaded section is roughly 8 mm, not including the bolt head.

Question 2

What size is an M8 bolt?

Accepted Answer

M8 bolt size is defined by thread diameter, which is 8 mm. For other dimensions, lengths vary from short fixings under 20 mm to structural bolts over 150 mm.

Question 3

What size spanner do I need for an M8 bolt?

Accepted Answer

Most M8 hex bolts use a 13 mm spanner or socket. However, it’s best to check the specific bolt head design, as some countersunk or flanged heads will need different drive types.

Question 4

What size drill bit do I need for an M8 bolt?

Accepted Answer

For clearance holes, a 9 mm drill bit is typically used with an M8 bolt. For anchor bolts or rawl bolts, follow the manufacturer’s recommended drill size.

Question 5

What are M8 nut dimensions?

Accepted Answer

An M8 hex nut (coarse pitch, 1.25 mm) typically has a width across flats of 13 mm (max) / 12.73 mm (min), a width across corners of about 14.38 mm, and a height of around 6.8 mm (max) / 6.44 mm (min).

M8 bolts

Cup Square Carriage Bolt & Nut BZP M8x50mm

Cup Square Carriage Bolt & Nut BZP M8x110mm

Cup Square Carriage Bolt & Nut BZP M8x130mm

Cup Square Carriage Bolt & Nut BZP M8x150mm

Cup Square Carriage Bolt & Nut BZP M8x180mm

Cup Square Carriage Bolt & Nut BZP M8x200mm

Cup Square Carriage Bolt & Nut BZP M8x65mm

Carriage Bolt & Nut M8 X 75mm Bright Zinc Plated

Unifix Light Washer M8 Bright Zinc Plated Bag of 30

Unifix Cup Square Hex Bolt & Nut M8 x 50mm Pack of 10

Buildbase Hexagon Nuts M8

OJ Cup Sq Hex Carriage Bolt 4.8 DIN 603/555 BZP - M8x40

OJ Economy - Mudguard Washers BZP - M8x30x1.5

Penny Washer Stainless Steel M8 x 25mm Dia Grey

Timco Nylon Nuts Type-P Zinc DIN982 M8 (10 Pack) 8NPP

Hex Nut & Washer BZP M8 (20)

Unifix Cup Square Hex Bolt & Nut M8 x 40mm Bright Zinc Plated Bag of 10

Unifix Cup Square Hex Bolt & Nut M8 x 130mm Bright Zinc Plated Bag of 5

Rawlplug Rawlbolt Shield Anchor Loose Bolt M8/25L 5pk

Rawlplug Rawlbolt Shield Anchor Loose Bolt M8/10L 5pk

Rawlplug Rawlbolt Loose Bolt M8 40mm Pack Of 5

Grange Fencing Metpost Anchor Bolts M8 X 65mm Pack Of 4