Size charts · Nuts
Nut sizes.
Five different products that happen to share a hexagon. Each has its own standard, its own height and its own size range, so each gets its own chart — pick the type you are after and you get the spanner size, the height and the pitch, drawn to proportion in the finish you need.
NT-01 / DWS·DAVENTRY
Full nut sizes
The everyday hex nut. Across flats, across corners, height and pitch, with the ISO figure beside the DIN one wherever they disagree.
M1.6 - M36 · DIN 934 · ISO 4032
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NT-02 / DWS·DAVENTRY
Nyloc nut sizes
Nylon insert lock nuts. Taller than a full nut over the collar, which is the figure people get caught by.
M3 - M30 · DIN 985 · ISO 10511
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NT-03 / DWS·DAVENTRY
Thin nut sizes
Half nuts and jam nuts. Same hexagon, about half the height, and no load rating - classes 04 and 05 only.
M3 - M36 · DIN 439 form B · ISO 4035
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NT-04 / DWS·DAVENTRY
Stover nut sizes
All-metal lock nuts. The crown is crimped so the thread grips, with no nylon to soften - the standard describes them in service to 150°C.
M3 - M24 · DIN 980 V · ISO 7042
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NT-05 / DWS·DAVENTRY
Flange nut sizes
The washer is part of the nut. Watch the spanner: DIN 6923 and DIN EN 1661 disagree, and both are sold.
M4 - M20 · DIN 6923 · DIN EN 1661
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NT-06 / DWS·DAVENTRY
K-nut sizes
Jet nuts. A far smaller hex than the thread suggests - M8 takes a 10mm spanner, not 13mm - in standard, captive washer and 650°C hi-temp.
M3 - M14 · no DIN or ISO · 1100 MPa
NT-07 / DWS·DAVENTRY
UNC & UNF full nut sizes
The imperial hex nut, 1/4 to 1 1/8 inch. Spanner size, across corners and thickness to ASME B18.2.2 — and no class 8; the inch world grades differently.
1/4" - 1 1/8" · ASME B18.2.2 · UNC / UNF
NT-08 / DWS·DAVENTRY
UNC & UNF nyloc nut sizes
The inch nyloc is a LIGHT hex: at 7/16, 3/4, 7/8 and 1 inch it takes a smaller spanner than the full nut. The chart that stops you grabbing the wrong one.
1/4" - 1" · IFI-100/107 · UNC / UNF
NT-09 / DWS·DAVENTRY
Imperial K-nut sizes
MS21042 — the inch jet nut most race kit was designed around. A 1/4-28 takes a 5/16 spanner, and the MS21043 hi-temp is 425°C, not the metric 650.
#2 - 5/8" · MS21042 / MS21043 · UNJF / UNJC
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.
DIN or ISO changes the spanner
An M10 nut takes a 17mm spanner if it is DIN 934 and a 16mm spanner if it is ISO 4032. It happens again at M12 and M14, and at M22 it flips the other way. Heights differ at nearly every size from M5 up. Every chart here prints the DIN figure, because that is what the UK trade buys, and shows the ISO value beside it wherever the two differ.
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
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.