HANDA. NINGBO

Part group 10 / 05 · Ningbo, China

Metric hex bolt dimensions,
M5 to M24 on one page.

One table for the four numbers that decide whether a hex bolt fits: pitch, across-flats, head height and the thread length b. Then the tolerance class and the grade, because those are what a drawing actually calls out.

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Specification

Hex Bolt Chart to drawing

M5
Pitch 0.8 mm · across flats s 8 mm · head height k 3.5 mm · DIN 931 thread length b 16 mm
M6
Pitch 1.0 mm · across flats s 10 mm · head height k 4.0 mm · DIN 931 thread length b 18 mm
M8
Pitch 1.25 mm · across flats s 13 mm · head height k 5.3 mm · DIN 931 thread length b 22 mm
M10
Pitch 1.5 mm · across flats s 16 mm · head height k 6.4 mm · DIN 931 thread length b 26 mm
M12
Pitch 1.75 mm · across flats s 18 mm · head height k 7.5 mm · DIN 931 thread length b 30 mm
M16
Pitch 2.0 mm · across flats s 24 mm · head height k 10.0 mm · DIN 931 thread length b 38 mm
M20
Pitch 2.5 mm · across flats s 30 mm · head height k 12.5 mm · DIN 931 thread length b 46 mm
M24
Pitch 3.0 mm · across flats s 36 mm · head height k 15.0 mm · DIN 931 thread length b 54 mm
The b rule
DIN 931 thread length is 2d + 6 mm up to 125 mm overall length, 2d + 12 mm from 125 to 200 mm, 2d + 25 mm above 200 mm. DIN 933 is threaded to the head, so b equals the length minus the head.
Tolerance
Thread class 6g as standard, 6h on request; across-flats and head height to the standard tolerance grade. Every batch goes over go / no-go gauges, and the measured values are on the inspection sheet.

Every dimension is taken from your drawing or sample. Where this page and your drawing disagree, your drawing wins.

Where these parts go

Applications

The four numbers that decide whether a bolt fits, on one page, so a drawing and a quote can be checked against the same reference.

Hex Bolts

DIN 931 and 933, class 8.8 / 10.9 / 12.9, hot-dip galvanised to ISO 10684.

Open page

Bolts

Hex, socket, flange, carriage and special-head bolts, class 8.8 to 12.9.

Open page

Nuts & Washers

Hex, nyloc and cap nuts; flat, spring and lock washers in four materials.

Open page

Threaded Rods

Full-thread rod, double-end and tap-end studs, cut to length.

Open page

Questions buyers ask

01
Why is the across-flats on a Chinese bolt sometimes a bit small?
Because the class and the standard are two separate promises. A bolt can be called 8.8 and still be under the minimum s if the die is worn. We hold s and k to the standard tolerance and report it; the first piece is photographed with a caliper for your file.
02
Is DIN 931 the same as ISO 4014?
Effectively yes for the common sizes: same head, same thread length rule. DIN 933 matches ISO 4017. Some drawing offices still write the DIN number, so we accept both and state which one we produced to.
03
What length do I order for a joint with a nut and washer?
Add the clamped thickness, the washer thickness, the nut height and two or three pitches of protrusion. If you send the joint sketch instead of a length, we work it out and come back with the number rather than guessing.
04
Do you roll or cut the thread?
Rolled, for M5 up to M24 in the classes we make. Rolling moves the grain along the thread profile instead of cutting across it, which is why a rolled 8.8 bolt takes more torque before it strips.
05
Can you hold 6h instead of 6g?
Yes, on request, and it matters when the bolt goes into a tapped hole in your own part rather than through a nut. State it on the drawing; it changes the die allowance, not the price.
06
What about imperial sizes?
UNC and UNF are made to the same process: 1/4-20, 5/16-18, 3/8-16, 1/2-13 and so on, with the head dimensions per ANSI B18.2.1. Send the inch callout and it is quoted as a separate line.

Next step

Send one drawing.
Get a costed sheet.

Drawing or sample, material, quantity, and the destination port. We reply within one working day with unit price, tooling, lead time and shipping.

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