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.
// 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.
| 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 |
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.
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.
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.