Size picker · Full nut · DIN 934
Full nut sizes.
The everyday hex nut. Pick a diameter and you get the spanner size, the height and the pitch, drawn to proportion in the finish you are after — with the ISO figure beside the DIN one wherever the two disagree, which on nut heights is nearly every size.
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Drawn to proportion from the standard dimensions. Illustration, not a photograph of the item.
Selected
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| Sym | Dimension | Value |
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Read the full nut size chart
| Size | Pitch | s — across flats | e — across corners | m — height | ISO 4032 differs |
|---|---|---|---|---|---|
| 0.35 | 3.2 | 3.41 | 1.3 | — | |
| 0.4 | 4 | 4.32 | 1.6 | — | |
| 0.45 | 5 | 5.45 | 2 | — | |
| 0.5 | 5.5 | 6.01 | 2.4 | — | |
| 0.7 | 7 | 7.66 | 3.2 | — | |
| 0.8 | 8 | 8.79 | 4 | m 4.7 | |
| 1 | 10 | 11.05 | 5 | m 5.2 | |
| 1.25 | 13 | 14.38 | 6.5 | m 6.8 | |
| 1.5 | 17 | 18.9 | 8 | s 16 · m 8.4 | |
| 1.75 | 19 | 21.1 | 10 | s 18 · m 10.8 | |
| 2 | 22 | 24.49 | 11 | s 21 · m 12.8 | |
| 2 | 24 | 26.75 | 13 | m 14.8 | |
| 2.5 | 27 | 29.56 | 15 | m 15.8 | |
| 2.5 | 30 | 32.95 | 16 | m 18 | |
| 2.5 | 32 | 35.03 | 18 | s 34 · m 19.4 | |
| 3 | 36 | 39.55 | 19 | m 21.5 | |
| 3 | 41 | 45.2 | 22 | m 23.8 | |
| 3.5 | 46 | 50.85 | 24 | m 25.6 | |
| 3.5 | 50 | 55.37 | 26 | m 28.7 | |
| 4 | 55 | 60.79 | 29 | m 31 |
Figures are the standards' nominal dimensions, each confirmed against two independent published tables — anything we could only source once reads "ask us" rather than printing a number we can't stand behind. Odd diameters like M7 and M9, left-hand threads and the finer pitches are all made, and availability varies by finish and class — ask us for anything you can't see.Figures are the standards' nominal dimensions, each confirmed against two independent published tables. Where only one table prints a figure, where two disagree, or where nobody publishes one at all, the row reads "ask us" rather than a number we can't stand behind. Imperial washers (BS 3410), the other BS 4320 forms, spring and shakeproof patterns and the hardness grades are all real too, and availability varies by finish — ask us for anything you can't see.
The 17 or 16 problem
An M10 nut takes a 17mm spanner if it is DIN 934 and a 16mm spanner if it is ISO 4032. Same thread, same bolt, different spanner. It happens again at M12 (19 or 18) and M14 (22 or 21), and at M22 it flips the other way — the ISO nut is the bigger one, 34 against 32.
That much is fairly well known. The part that catches people is height: DIN and ISO nuts are different thicknesses at every size from M5 to M36, not just at those four. An ISO nut is always the taller one, by 0.2mm at M6 and a full 2mm at M20. If you are working to a stack-up, or you have a set length of thread poking through, that is the figure that bites.
The table above prints the DIN figure, because that is what the UK trade buys and what our own records call it, and shows the ISO value beside it wherever the two differ.
Which class of nut for which bolt
A nut is not graded like a bolt. It carries a single number — its proof load class — and the rule is simple: the nut class is the digit to the left of the bolt class. A class 8 nut for an 8.8 bolt, class 10 for a 10.9, class 12 for a 12.9. Put a class 6 nut on a 10.9 bolt and the nut strips before the bolt reaches its rating, which is exactly the failure you do not want.
Stainless works differently again. On a stainless bolt the number is a tenth of the tensile strength, so A4-80 means 800 MPa. On a stainless nut it is a tenth of the proof load, and the standard's partner for an A4-80 bolt is an A4-70 nut — A4-80 is not a nut designation at all, however often you hear it asked for.
Not sure which you need?
Bring the old one in, or send us a photo. We are on Baird Close in Daventry with metric and imperial stock across the common classes and finishes.
More size charts
Every size, drawn to scale.
Hex setscrews
DIN 933 · full thread
Hex bolts
DIN 931 · part thread
Socket cap screws
DIN 912
Low head cap screws
DIN 7984
Button head screws
ISO 7380-1
Flanged button heads
ISO 7380-2
Countersunk socket screws
DIN 7991
Grub screws
DIN 913–916 · five points
Nuts
DIN 934 · nyloc · thin · Stover · flange
Washers
ISO 7089 · BS 4320 · penny
Not sure what the markings on the head mean? Bolt grades explained covers 8.8, 10.9, 12.9, stainless A2 and A4, and the imperial SAE grades.
All of it comes off the shelf at Baird Close — see the full fasteners & fixings range, or every size guide.