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Notes:
The screw and nut sizes are in accordance with BS 3692:1967 (ISO 272 equivalent).    This standard has now been superseded by BS 3692:2001. (The data has not yet been checked against the latest revision. ). The thread form is in accordance with BS 3643:2007

All dimensions in millimetres

Relevant Standards

BS 3643 Part 1:2007..ISO metric screw threads. Principles and basic data

BS 3643 Part 2:2007..ISO metric screw threads. Specification for selected limits of size

BS 3692:2001..ISO metric precision hexagon bolts, screws and nuts. Specification




Table of Bolt Sizes ...ISO metric precision hexagon bolts , Coarse Thread Series, Bolt tolerance class 6g

Thread Form to BS 3643

Nominal (D) Thread. Bolt dia Bolt Head Bolt Nut
Size Pitch Major(d)
max - min
Minor(d3 )
max - min
Pitch Diameter (d2 )
max - min
Thick (Zb) Acc/Flats (A/F)
max - min
Acc./Corn (A/C)
M3 0,5 2,980 - 2,874 2,439 -2,272 2,655 - 2,580 2,125 5,50 - 5,38 6,40
M4 0,7 3,978 - 3,838 3,220 - 3,002 3,523 - 3,433 2,925 7,00 - 6,85 8,10
M5 0,8 4,976 - 4,826 3,869 - 4,110 4,456 - 4,361 3,650 8,00 - 7,85 9,20
M6 1,0 5,974 - 5,794 4,891 - 4,596 5,324 - 5,212 4,150 10,00 - 9,78 11,50
M8 1,25 7,972 - 7,760 6,272 - 6,619 7,160 - 7,042 5,650 13,00 - 12,73 15,00
M10 1,5 9,968 - 9,732 8,344 - 7,938 8,994 - 8,862 7,180 17,00 - 16,73 19,60
M12 1,75 11,966 - 11,701 10,072 - 9,601 10,829 - 10,679 8,180 19,00 - 18,67 22,10
M16 2,0 15,962 - 15,682 13,797 - 13,271 14,663 - 14,503 10,180 24,00 - 23,67 27,70
M20 2,5 19,958 - 19,623 17,252 - 16,624 18,334 - 18,164 13,215 30,00 - 29,67 34,60
M24 3,0 23,952 - 23,577 20,701 - 19,955 22,003 - 21,803 15,215 36,00 - 35,58 41,60
M30 3,50 29,947 - 29,522 26,158 - 25,306 27,674 - 27,462 19,260 46,00 - 45,38 53,1
M36 4,00 35,940 - 35,465 31,610 - 30,654 33,342 - 33,118 23,260 55,00 - 54,26 63,5




Nuts Sizes, Coarse Thread Series

Nut tolerance class 6H are dimensioned in BS3692

Thread form to BS 3643


Nominal Thread. Nut Diameter Nut
Size Pitch Major (D) Minor (D1 )
Max - min
Thick (Zn)
M3 0,5 3,000 2,599 - 2,459 2,40
M4 0,7 4,000 3,422 - 3,242 3,20
M5 0,8 5,000 4,334 - 4,134 4,00
M6 1,0 6,000 5,153 - 4,917 5,00
M8 1,25 8,000 6,912 - 6,647 6,50
M10 1,5 10,000 8,676 - 8,376 8,00
M12 1,75 12,000 10,441 - 10,106 10,00
M16 2,0 16,000 14,210 - 13,835 13,00
M20 2,5 20,000 17,744 - 17,294 16,00
M24 3,0 24,000 21,252 - 20,752 19,00
M30 3,5 30,000 26,771 - 26,211 24,00
M36 4,0 36,00 32,270 - 31,670 29,00





Bolt Sizes ...ISO metric precision hexagon bolts , Fine thread series

Bolt tolerance class 6g are dimensioned in BS3692:1967


Nominal Thread. Bolt dia (d) Bolt Head Bolt Nut
Size Pitch Major
max - min
Minor
max - min
Pitch Diameter
max - min
Thick (Zb) Acc/Flats
max - min (A/F)
Acc./Corn (A/C)
M6 0,75 5,978 - 5,838 5,166 - 4,929 5,491 - 5,391 4,150 10,00 - 9,78 11,50
M8 1,00 7,974 - 7,794 6,891 - 6,596 7,324 - 7,212 5,650 13,00 - 12,73 15,00
M10 1,25 9,972 - 9,760 8,619 - 8,272 9,160 - 9,042 7,180 17,00 - 16,73 19,60
M12 1,25 11,972 - 11,760 10,619 - 10,258 11,160 - 11,028 8,180 19,00 - 18,67 22,10
M16 1,50 15,968 - 15,732 14,344 - 13,930 14,994 - 14,854 10,180 24,00 - 23,67 27,70
M20 1,5 19,968 - 19,732 18,344 - 17,930 18,994 - 18,854 13,215 30,00 - 29,67 34,60
M24 2,0 23,962 - 23,682 21,797 - 21,261 22,663 - 22,493 15,215 36,00 - 35,58 41,60
M30 2,0 29,962 - 29,682 27,797 - 27,261 28,663 - 28,493 19,260 46,00 - 45,38 53,1
M36 3,00 35,952 - 35,577 32,704 - 31,955 34,003 - 33,803 23,260 55,00 - 54,26 63,5





Nuts Sizes - Fine Thread Series..

Nut tolerance class 6H are dimensioned in BS3692:1967

Nominal Thread. Nut Diameter Nut
Size Pitch Major Minor
Max - min
Thick (Zn)
M6 0,75 6,000 5,378 - 5,188 5,00
M8 1,00 8,000 7,153 - 6,917 6,50
M10 1,25 10,000 8,912 - 8,647 8,00
M12 1,25 12,000 10,912 - 10,647 10,00
M16 1,50 16,000 14,676 - 14,376 13,00
M20 1,50 20,000 18,676 - 18,376 16,00
M24 2,0 24,000 22,210 - 21,835 19,00
M30 2,0 30,000 28,210 - 27,835 24,00
M36 3,0 36,00 33,252 - 32,752 29,00





Washers.. Plain Washers , bright metric series

Bright Washers are dimensioned in BS4320: 1968

Nominal Washer Diameter Washer Thickness
Size Internal
max - min
External
max - min
Thick
max - min
Thin
M3 3,4 - 3,2 7,0 - 6,7 0,6 - 0,4 -
M4 4,5 - 4,3 9,0 - 8,7 0,9 - 0,7 -
M5 5,5 - 5,3 10,0 - 9,7 1,1 - 0,9 -
M6 6,7 - 6,4 12,5 - 12,1 1,8 - 1,4 0,9 - 0,7
M8 8,7 - 8,4 17,0 - 16,6 1,8 - 1,4 1,1 - 0,9
M10 10,9 - 10,5 21,0 - 20,5 2,2 - 1,8 1,45 - 1,05
M12 13,4 - 13,0 24,0 - 23,5 2,7 - 2,3 1,8 - 1,4
M16 17,4 - 17,00 30,0 - 29,5 3,3 - 2,7 2,2 - 1,8
M20 21,5 - 21,0 37,0 - 36,2 3,3 - 2,7 2,2 - 1,8
M24 25,5 - 25,0 44,0 - 43,2 4,3 - 3,7 2,7 - 2,3
M30 31,6 - 31,0 56,0 - 55,0 4,3 - 3,7 2,7 - 2,3
M36 37,6 - 37,0 66,0 - 65,0 5,6 - 4,4 3,3 - 2,7





Washers.. Plain Washers , Black metric series

Black Washers are dimensioned in BS4320: 1968

Nominal Washer Diameter Washer Thickness
Size Internal
max - min
External
max - min
Thickness
max - min
M5 5,8 - 5,5 10,0 - 9,2 1,2 - 0,8
M6 7,0 - 6,6 12,5 - 11,7 1,9 - 1,3
M8 9,4 - 9,0 17,0 - 16,2 1,9 - 1,3
M10 11,5 - 11,0 21,0 - 20,2 2,3 - 1,7
M12 14,5 - 14,0 24,0 - 23,2 2,8 - 2,2
M16 18,5 - 18,00 30,0 - 29,2 3,6 - 2,4
M20 22,6 - 22,0 37,0 - 35,8 3,6 - 2,4
M24 26,6 - 26,0 44,0 - 42,8 4,6 - 3,4
M30 33,8 - 33,0 56,0 - 54,5 4,6 - 3,4
M36 39,8 - 39,0 66,0 - 64,5 6,0 - 4,0
M42 45,8 - 45,0 78,0 - 76,5 8,2 - 5,8
M48 53,0 - 52,0 92,0 -90,0 9,2 - 6,8

For DIN125 Plain Washers (Overall dimensions) Din 125 Washer



Useful Links
  1. Metric Thread Sizes..Metric THREAD sizes from Tribology - abc
  2. Metric Thread Sizes..Metric THREAD sizes from Newmantools - abc
  3. Metric Thread Tolerances..Metric Thread tolerances from Fullermetric
  4. Metrication.com..Information on metric threads and other metric subjects
  5. Maryland Metrics..Comprehensive information on metric screws threads.

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Last Updated 18/06/2008