Hex Bolts & Hex Head Bolts — Machined to Your Size

What We Can Actually Make

Most custom bolt pages say "any size, any material". That helps nobody decide. Here is the real envelope — if your bolt falls inside it, we can quote it today; if it falls outside, the hand-off links below point at the supplier or page that fits better.

Hex Head Bolt Dimensions — DIN 933 / 931, M2 to M72

The two numbers every job needs: the spanner (width across flats s) and the head height k. They apply to DIN 933 (full thread) and DIN 931 (plain shank) alike — the head is the same, only the thread length differs. The same s figures serve the matching steel hex nut, because hex bolts and nuts share the across-flats table.

Marked cells are the trap: on M10, M12, M14 and M22 the DIN and ISO across-flats differ — 17/16, 19/18, 22/21, and on M22 the ISO head is bigger, 32/34. A socket that spins on a new bolt usually means the bolt is the other standard, not the wrong size.

Two spanner figures worth keeping in your head past the table’s common range: an M30 nut or bolt takes 46 mm, an M36 nut takes 55 mm. Both sizes exist in fine pitch too — an M30×1.5 nut uses the same 46 mm hex but is a machined part, not a shelf item. Nut heights to DIN 934: an M30 nut is 24 mm high, an M36 nut 29 mm. That stocked-or-cut borderline is the subject of the next table.

One Family, Five Pages — Where Your Size Lives

Hex bolts and nuts run from M2 grub-screw territory to nuts you lift with two hands, and no single chart serves that span honestly. This page holds the family together; the heavy, structural and large sizes each get the full treatment on their own page:

Around the family sit the working references: the metric bolt torque chart for tightening the joint, and the clearance hole chart for the hole it passes through.

Which Hex Bolts You Should Just Buy — and Which Have to Be Cut

EKINSUN LTD is a custom parts manufacturer, and honesty about that line saves everyone money: a stocked size from a distributor beats any one-off on price, every time. The split runs like this:

Before you order any bolt in this table, read the pitch of what it screws into. A stock DIN 933 or ISO 4017 bolt carries the coarse pitch in the table; ten pitches on a rule give the pitch times ten — 17.5 mm at M12, 20 at M16, 25 at M20, 30 at M24 — and a nut or tapped hole that reads a different number is a fine thread the stock bolt will not enter. The size is easy; the pitch is what gets bolts sent back. If diameter, pitch and length are all in the catalogue, buy the stock bolt. If the pitch is fine, or the length is between standard steps, or the head must be drilled, send the three numbers and we turn the bolt to them. How to read the pitch, and the inch traps →

Cold-Headed, Hot-Forged or Machined?

Hex bolts are made three ways, and the cheapest one depends entirely on your quantity and how standard the part is. This is the single most useful thing to get right before you ask anyone for a price:

Need 20,000 standard M10×40 class 8.8 zinc bolts? Buy them from stock, or from a cold-heading house — genuinely cheaper, and we will say so. Need one M16×1.5 left-hand bolt for a machine built in 1978, or forty M12 bolts with a 21 mm across-flats head that no catalogue lists? That is what a lathe is for.

No Drawing? Send the Bolt.

Every other custom bolt manufacturer on this search result asks for "your drawings, blueprints, or detailed specifications" before they will quote. That is a reasonable request if you are an OEM with a drawing office. It is useless if you are a maintenance engineer holding two halves of a bolt that sheared on a Sunday.

We work the other way round. You send evidence, we produce the drawing.

• A photo next to a ruler or caliper — enough to start a quote on most bolts
• A hand sketch with dimensions written on it, however rough
• The original bolt, posted to us — including a broken one; both halves together carry the full geometry
• A drawing or STEP file, if you have one — this is simply the fastest route

Our engineers measure the thread with gauges, confirm diameter, pitch, hand, length, head form and across-flats, then send you a drawing to approve. Nothing is cut until you have confirmed that drawing. The drawing is yours and is kept on file, so a reorder in two years is a one-line email. Full detail on the process is on ordering with no CAD and reverse engineering from a sample.

Materials & Property Classes

Material determines strength, corrosion behaviour and cost. Where a class is marked on the head of your original bolt, tell us — we match the class, not just the look.

• EN 10204 3.1 material certificate traceable to the bar heat, on request
• Hardness and tensile testing where a property class is being certified
• Finishes: plain, black oxide, zinc plate, geomet, hot-dip galvanised, passivated stainless, anodised aluminium

Cost, Quantity and Lead Time

No custom bolt can be priced without the geometry, but the shape of the pricing is predictable, and nobody else on this page will tell you it:

On quantity: the first piece carries the setup. That means one bolt is never cheap per piece — but it is possible, which is the point. Unit price falls sharply between 3 and 50 pieces as setup is shared, and again above 50. If you need one now and fifty later, say so in the enquiry and we will quote both tiers together.

If Your Bolt Isn't Quite This

Hex bolts are one branch of a larger set. These pages cover the neighbouring jobs:

Frequently Asked Questions