Bolt Diameter

Standard Thread Pitch (mm)

Fine Thread Pitch (mm)

Extra Fine Thread Pitch (mm)

4mm

0.70

-

-

5mm

0.80

-

-

6mm

1.00

-

-

7mm

1.00

-

-

8mm

1.25

1.00

-

10mm

1.50

1.25

1.00

12mm

1.75

1.50

1.25

14mm

2.00

1.50

-

16mm

2.00

-

-

18mm

2.50

-

-

20mm

2.50

-

-

24mm

3.00

-

-

Size Identification: Metric bolts are written down as an ‘M’ followed by 3 numbers. For example M10x1.25x35 The first number is the diameter, the second the thread pitch, and the third the length all in millimeters. The example is therefore a 10mm diameter fine thread bolt 35mm long

Thread Pitch: The distance from one thread to the next, measured down the length of the fastener