Bolt and nut size table

The table with metric bolt and nut sizes helps in determining the correct size of bolt and nut for each application.

The definitions of the terms can be found below the table.

Coarse thread bolts

Nominale boutdiameterSchroefdraad in mmDiameter in mmMoermaat in mm
M161.51624
M1821827
M181.51827
M2022030
M201.52030
M2222232
M221.52232
M2422436
M241.52436
M2722741
M271.52741
M3023046
M301.53046
M3323350
M331.53350
M3633655
M361.53655
M3933960
M4234265
M4534570
M4834875
M5235280
M5645685
M6046090
M6446495
M68468100
M72472105
M76476110
M80480115
M85485120
M90490130
M1004100145
M1104110155
M1254125180

Fine thread bolts

Nominale boutdiameterSchroefdraad in mmDiameter in mmMoermaat in mm
M101.51017
M121.751219
M1421422
M1621624
M182.51827
M202.52030
M222.52232
M2432436
M2732741
M303.53046
M333.53350
M3643655
M3943960
M424.54265
M454.54570
M4854875
M5255280
M565.55685
M605.56090
M6466495
M68668100
M72672105
M76676110
M80680115
M85685120
M90690130
M1006100145
M1106110155
M1256125180
M1406140200
M1606160230
M1004100
M1104110
M1254125

Definitions

Nominal diameter
The diameter equal to the external diameter of the threads or the overall diameter of the part. Nominal diameter is more of a label than a size. For example, a bolt and nut may be described as being ½” diameter. But neither the external threads of the bolt nor the internal threads of the nut are exactly .500 in diameter. In fact, the bolt diameter is a little smaller and the nut diameter a little larger. But it is easier to specify the components by a single size designation since the bolt and nut are mating components.

Pitch
Pitch is the distance from the crest of one thread to the next or the distance from one thread groove to the next, measured from crest to crest. Pitch is also described as the number of threads per inch.

Diamater
The smallest or largest pitch diameter that fits onto a screw or into a nut, including all of the form deviations such as lead, thread angle, taper, and roundness. Functional diameter is a measure of the ability to assemble the thread.

Threads
A raised, helical rib or ridge around the interior or exterior of a cylindrically shaped object. Threads are found on screws, nuts, and bolts.

Coarse threads & fine threads
Coarse threads are those with larger pitch (fewer threads per axial distance), and fine threads are those with smaller pitch (more threads per axial distance).

Thread pitch
Also known as “pitch.” It is the distance from the crest of one thread to the next, or the distance from one thread groove to the next, measured from crest to crest. It determines how far a screw moves into a nut or material with each turn. The thread pitch is also described as the number of thread lines per mm.