Size picker · Hex socket drive · ISO 7380-1
Button head screw sizes.
A low domed head with an internal hex drive — chosen where a cap screw head would snag or look wrong, and where nothing needs to sit flush. Pick a diameter and length for the head figures and the key size.
1 Pick a diameter
2 Pick a length
Choose a diameter first.
Your browser could not draw the 3D view. The dimensions beside it are unaffected.
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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Job stopped? Ring 01327 877577 and we'll check the stock while you're on.
Read the full ISO 7380-1 size chart
| Size | 3 | 4 | 5 | 6 | 8 | 10 | 12 | 14 | 15 | 16 | 18 | 20 | 22 | 25 | 30 | 35 | 40 | 45 | 50 | 55 | 60 | 65 | 70 | 75 | 80 | 90 | 100 | 110 | 120 | 140 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| M2.5 | ||||||||||||||||||||||||||||||
| M3 | ||||||||||||||||||||||||||||||
| M4 | ||||||||||||||||||||||||||||||
| M5 | ||||||||||||||||||||||||||||||
| M6 | ||||||||||||||||||||||||||||||
| M8 | ||||||||||||||||||||||||||||||
| M10 | ||||||||||||||||||||||||||||||
| M12 | ||||||||||||||||||||||||||||||
| M16 |
The range shown is what fastener wholesalers commonly list — not a claim about what the standard mandates, and not a stock list. In-between lengths (85, 95, 170…), lengths past 300mm and odd diameters like M7 are made too, and availability varies by finish and grade — ask us for anything you can't see.
What a button head is for
The dome is wide and shallow, so it spreads the load on soft or slotted material and leaves nothing sharp to catch on. The trade-off is strength: the standard class is 10.9, not 12.9, and the shallow socket means less key engagement than a cap screw — do not lean on the key.
Where the head must not stand proud at all, use a countersunk socket screw. Where it needs a wider bearing face, a flanged button head saves fitting a washer.
Not sure which you need?
Bring the old one in — Baird Close, Daventry — and we will match it.
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
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.