Every number a dowel pin job needs on one page: ISO 8734 / DIN 6325 m6 limits for hardened ground pins Ø1–20 mm, ISO 2338 h8 for unhardened parallel pins, the H7 press-fit hole to ream, internal-thread sizes for ISO 8735 / DIN 7979 extractable pins, hardness classes and DIN↔ISO equivalents. Real HTML tables and an instant calculator. Jump to your size:
Compiled and reviewed by the EKINSUN engineering team — we are a custom manufacturing & OEM partner for non-standard pins and fasteners, producing through ISO 9001 certified manufacturing partners. Diameter limits follow ISO 286-2 (m6 / h8 / H7); pin standards referenced: ISO 8734, DIN 6325, ISO 2338, ISO 8735, DIN 7979. Always defer to the assembly drawing where a fit is specified. Last reviewed 3 Aug 2026.
This chart is here because we turn these pins ourselves: EKINSUN machines dowel pins to drawing, including oversize pins for bores that have already worn — from one piece. The standard sizes below are the part anyone can look up, and standard pins are cheaper from a stockist — or ask us, we may have them in stock. What reaches us is the pin that is not in the catalogue: an oversize ground to the bore as measured, a non-standard length, or a material the standard does not cover. See dowel pins machined to drawing.
// Dowel Pin Limit Calculator — pick value & diameter
Limits per ISO 286-2. m6 pin in an H7 reamed hole gives the standard light-interference location fit; G7 or F7 gives a removable slip fit in the mating plate. Safety-critical or specified fits: verify against the drawing.
One row per nominal size: the m6 limits a hardened ground dowel to ISO 8734 / DIN 6325 is actually made to, the h8 limits of an unhardened ISO 2338 parallel pin, the H7 press-fit hole, and the internal thread you get if you order the extractable version instead.
Need a dowel pin in one of these diameters, or in a length, material or tolerance the catalogue skips? Any row is made to order from 1 piece, standard sizes can also be supplied from stock, quote in 12 hours, delivered DDP. Get a price on WhatsApp · Quote form
| Nominal Ø | ISO 8734 / DIN 6325 pin (m6) | ISO 2338 pin (h8) | Press-fit hole (H7) | ISO 8735 internal thread |
|---|---|---|---|---|
| Ø1 | 1.002 – 1.008 | 0.986 – 1.000 | 1.000 – 1.010 | — |
| Ø1.5 | 1.502 – 1.508 | 1.486 – 1.500 | 1.500 – 1.510 | — |
| Ø2 | 2.002 – 2.008 | 1.986 – 2.000 | 2.000 – 2.010 | — |
| Ø2.5 | 2.502 – 2.508 | 2.486 – 2.500 | 2.500 – 2.510 | — |
| Ø3 | 3.002 – 3.008 | 2.986 – 3.000 | 3.000 – 3.010 | — |
| Ø4 | 4.004 – 4.012 | 3.982 – 4.000 | 4.000 – 4.012 | — |
| Ø5 | 5.004 – 5.012 | 4.982 – 5.000 | 5.000 – 5.012 | — |
| Ø6 | 6.004 – 6.012 | 5.982 – 6.000 | 6.000 – 6.012 | M4 |
| Ø8 | 8.006 – 8.015 | 7.978 – 8.000 | 8.000 – 8.015 | M5 |
| Ø10 | 10.006 – 10.015 | 9.978 – 10.000 | 10.000 – 10.015 | M6 |
| Ø12 | 12.007 – 12.018 | 11.973 – 12.000 | 12.000 – 12.018 | M6 |
| Ø14 | 14.007 – 14.018 | 13.973 – 14.000 | 14.000 – 14.018 | M8 |
| Ø16 | 16.007 – 16.018 | 15.973 – 16.000 | 16.000 – 16.018 | M8 |
| Ø20 | 20.008 – 20.021 | 19.967 – 20.000 | 20.000 – 20.021 | M10 |
Need a dowel pin in a diameter, length or tolerance no catalogue lists? EKINSUN is a custom parts manufacturer: we make dowel pins, stepped pins and pins with an internal thread to your drawing, sketch or sample — hardened steel, 303 (1.4305), 304 or 316L stainless steel — from 1 piece, quoted in 12 hours and shipped duties paid. Already a catalogue size? Ask us too — we may have it in stock, and larger quantities cost less per piece. All custom fasteners →
Lengths: the standard series steps 4, 5, 6, 8, 10, 12, 16, 20, 24, 28, 32, 36, 40, 45, 50, 60, 70, 80, 90, 100 mm, with availability narrowing by diameter. As a manufacturer we machine any intermediate length, and diameters above Ø20 or between the listed sizes — the table is what catalogues stock, not what exists.
The pin is the constant; the fit lives in the hole. Typical toolroom practice for a two-plate fixture or die set:
Hole already worn or re-reamed oversize? We machine oversized dowel pins to restore the original fit — the overstep you specify, hardened and ground like the standard pin, from one piece. See our custom dowel pins page or send the hole's measured size for a 12-hour quote.
| Standard | Type | Hardness | DIN / ISO counterpart |
|---|---|---|---|
| ISO 8734 A | Solid, through-hardened, ground | 550–650 HV30 (≈52–58 HRC) | DIN 6325 |
| ISO 8734 B | Solid, case-hardened, ground | ≈600–700 HV surface, tougher core | — |
| ISO 8734 C1 | Solid, martensitic stainless | 460–560 HV30 | — |
| DIN 6325 | Solid, through-hardened, ground | ≈60 HRC (58–62 typical catalogue spec) | ISO 8734 A |
| ISO 2338 | Solid, unhardened (m6 or h8) | ≈125–245 HV30; A1/A4 stainless | DIN 7 |
| ISO 8735 A | Internal thread, hardened, ground | 550–650 HV30 | DIN 7979 D |
| ASME B18.8.2 | Inch series, incl. standard oversizes | per grade | — (inch) |
The practical read: sizes interchange between DIN 6325 and ISO 8734 A, but the hardness clauses are written differently — if your drawing calls one standard by name and the certificate matters, order to that exact standard. We supply either, with EN 10204 3.1 certificates on request through our partners' ISO 9001:2015 system.
Pin m6: 6.004–6.012 mm (ISO 8734 / DIN 6325). Press-fit hole H7: 6.000–6.012 mm. Extractable version: M4 internal thread.
Pin m6: 8.006–8.015 mm. Press-fit hole H7: 8.000–8.015 mm. Extractable: M5 thread.
Pin m6: 10.006–10.015 mm. Press-fit hole H7: 10.000–10.015 mm. Extractable: M6 thread.
Pin m6: 12.007–12.018 mm. Press-fit hole H7: 12.000–12.018 mm. Extractable: M6 thread.
Sizing pins for a job you can't buy off the shelf? Odd diameters, oversize repair pins, stainless 303/304/316/416, brass, 6061/7075 aluminium, titanium or plastic dowels, mixed ISO 8734 + ISO 8735 sizes on one PO — we machine custom dowel pins and custom taper pins from 1 piece. Pair this chart with the clearance hole & tap drill chart and limits & fits chart for the full workflow.
When this chart stops being enough: Every size above assumes a fresh, correctly reamed hole. The jobs that reach us are the ones where it is not: the hole is already worn oversize, so no standard m6 pin will ever be tight in it again and the only real fix is a pin cut to the hole that exists, supplied as a measured pair; the size is imperial or from a machine whose pins are no longer made, where the chart has no row at all; the length is not a stocked one, which is common on locating pins in fixtures; and the pin has to be softer than the hole on purpose, so that a crash shears the pin instead of wrecking the casting - a decision no size chart can make for you. We machine the part that the table cannot describe — dowel and locating pins to a measured size, worn holes: oversize pins and repair bushes, or pins copied from a sample. From one piece, quoted within 12 hours.
These tolerances are for pins that are pressed home and never come out again. For the removable kind — clevis, lynch and ring-head pins — the sizes that matter are the clip hole and the chain wire, tabulated in lock pins with a retaining chain.
When two dowels locate a plate, one goes in a reamed round hole and the other in a short slot, since two round holes jam if their spacing differs by 0.02 mm; plates made this way are on adapter and mounting plates, and plates with whole grids of 12 mm reamed holes on fixture and tooling plates.
Pins held axially by a circlip instead of a press fit need a DIN 471 groove; groove diameter, width and edge margin by pin size are in the circlip groove size chart.
Hardened ground dowels (ISO 8734 / DIN 6325) are m6 — Ø6 measures 6.004–6.012 mm. Unhardened ISO 2338 pins come in m6 or h8.
Same m6 sizes, interchangeable in practice. DIN 6325 is the older German standard (≈60 HRC typical); ISO 8734 splits into type A through-hardened 550–650 HV30, type B case-hardened, C1 martensitic stainless. If the drawing names one, certify to that one.
ISO 8734 is solid; ISO 8735 adds an internal thread so the pin pulls out of a blind hole (DIN predecessor: DIN 7979 D). Blind hole → 8735; through hole → 8734.
Press fit: H7 (6.000–6.012 mm). Removable slip fit in the mating plate: G7 or F7, or a slip bushing. State the fit on the drawing.
A = through-hardened 550–650 HV30, the default. B = case-hardened skin (~600–700 HV) over a tougher core for shock loading. C1 = martensitic stainless, 460–560 HV30.
No — roughly 125–245 HV30 steel (or A1/A4 stainless), for light location duty. For wear resistance use ISO 8734 / DIN 6325.
Inch dowels follow ASME B18.8.2, including its standard oversize series. We machine inch and metric alike, plus any in-between diameter.
Yes — odd and oversize diameters, any length, stepped or internally threaded, in hardened steel, stainless 303/304/316/416, brass, 6061/7075, titanium or plastics. From 1 piece, quote in 12 hours, no CAD needed.
ISO 8734 pins are solid. ISO 8735 pins are also hardened and ground to m6 but have an internal thread, so the pin can be pulled out of a blind hole with an extractor screw — the DIN predecessor is DIN 7979 form D. Use ISO 8735 wherever the hole is blind and the pin must come out again.
Inch dowel pins follow ASME B18.8.2, which also defines standard oversize series for re-reamed holes. We machine inch and metric dowels alike — including oversize and intermediate diameters no catalogue stocks.
Odd diameter, oversize for a worn hole, ISO 8735 with thread, special material — we machine custom dowel pins from 1 piece. Send a size list, drawing or photo.
Standard ISO 8734 / 8735 sizes, oversize repair pins and non-standard dowels machined to drawing — mixed sizes on one PO, MOQ 1, quote in 12 hours.