# Studs, DIN 938 and DIN 939 (double-end studs): thread length of the nut end, M5/M6 to M30, nominal lengths

> What are the thread lengths of a DIN 938 or DIN 939 stud, and what lengths does each size come in?

- Category: Hardware › Fasteners
- Kind: Standard part
- Basis: Böllhoff's DIN 938 and DIN 939 steel 5.8 data sheets (metric coarse thread), with fasten.it's DIN 939 scope text; numbers only
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**Exact dimensions.** Every file is drawn at true size with no tolerance added. The holes and pins that meet another part are listed below under Mating features, with the fit each joint needs; open those by your process's clearance before making the part.

## Notes

- DIN 938 studs have a screw-in end of about 1 × d (for steel into steel) and DIN 939 studs about 1.25 × d (mainly for cast iron); metric coarse thread, product grade A in the fasten.it scope text. The Böllhoff sheets tabulate (mm): thread pitch P; the thread length of the nut end in three length bands (l up to 125, up to 200, over 200 mm) in the column the sheet calls b (the sheets' b / b1 / b2 labelling is ambiguous in the text read, so it is named here by its function and both sheets print identical values); ds nominal, min and max for DIN 938 (the reduced-shank diameter; M27 prints ds 25 as the sheet does); and the z1 / z2 columns as printed (not defined in the text read). For DIN 939 the screw-in length b1 is the first value after the length bands: M6 7.5, M8 10, M10 12, M12 15, M16 20, M20 25, M24 30, M27 35 mm, which equals 1.25 × d. For DIN 938 the sheet gives the screw-in end only as 'approx. 1 d', so no b1 values are tabulated.
- Lengths printed by the sheets (mm). DIN 938: 22, 25, 28, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, 105, 110, 115, 120, 125, 130, 135, 140, 150, 160, 170, 180, 190, 200. DIN 939: 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 80, 90, 100, 105, 110, 115, 120, 125, 130, 135, 140, 150, 160, 170, 180, 190, 200. Which length is stocked for which diameter is an availability matrix on the sheets and was not readable, so it is not given. Length tolerances are on the sheets (for example DIN 939 l = 25: 24.58 to 25.42 mm; l = 100: 99.30 to 100.70 mm; l = 200: 199.08 to 200.92 mm).
- fasten.it prints DIN 939 as covering metric coarse M4 to M52 and fine M8x1 to M52x3 and its title says '~1.25 d' while its scope says '~1.5 d' for the stud end; its table was not reproducible, so only the Böllhoff values are used and the 1.25 d figure agrees with Böllhoff's b1 values. The DIN 938 sheet as read covers M5 to M30; the DIN 939 sheet as read covers M6 to M27 (the text read may have been cut short, so the standard's range is wider).
- No file: a stud is a plain cylinder with a chamfer and a thread, and the plain-cylinder rule for Xem files rules out an envelope. McMaster-Carr lists DIN 939 studs with per-part STEP; the category is linked, not copied. Threaded rod is on threaded-rod-metric-din-976; nuts are on hex-nuts-metric.

## Mating features (exact size; open press / slide / run / socket by your process clearance, leave designed and clamp as drawn)

| feature | exact | mates with | fit | files |
|---|---|---|---|---|
| screw-in end | b1 ~ 1 d (DIN 938) or 1.25 d (DIN 939): DIN 939 M6 7.5, M8 10, M10 12, M12 15, M16 20, M20 25, M24 30, M27 35 mm | tapped blind hole of the same metric coarse thread, depth at least b1 (steel for 938, cast iron for 939) | designed | all |
| nut end | thread length b: M10 26 mm (l up to 125), 32 (up to 200), 45 (over 200); M12 30 / 36 / 49 mm | hex nut of the same metric thread (hex-nuts-metric) | designed | all |

## Sizes

| standard | thread | pitch P (mm) | b1 screw-in end (mm) | thread length b, l ≤ 125 (mm) | b, 125 < l ≤ 200 (mm) | b, l > 200 (mm) | ds nominal (mm) | ds min / max (mm) | z1 min / max; z2 (mm, as printed) |
|---|---|---|---|---|---|---|---|---|---|
| DIN 938 | M5 | 0.8 | ≈ 1 d (sheet text) | 16 | 22 | – | 5 | 4.82 / 5 | 0.8 / 1.0; 2 |
| DIN 938 | M6 | 1 | ≈ 1 d (sheet text) | 18 | 24 | – | 6 | 5.82 / 6 | 1.0 / 1.25; 2.5 |
| DIN 938 | M8 | 1.25 | ≈ 1 d (sheet text) | 22 | 28 | – | 8 | 7.78 / 8 | 1.25 / 1.6; 3.2 |
| DIN 938 | M10 | 1.5 | ≈ 1 d (sheet text) | 26 | 32 | 45 | 10 | 9.78 / 10 | 1.5 / 1.9; 3.8 |
| DIN 938 | M12 | 1.75 | ≈ 1 d (sheet text) | 30 | 36 | 49 | 12 | 11.73 / 12 | 1.75 / 2.2; 4.3 |
| DIN 938 | M16 | 2 | ≈ 1 d (sheet text) | 38 | 44 | 57 | 16 | 15.73 / 16 | 2.0 / 2.5; 5 |
| DIN 938 | M20 | 2.5 | ≈ 1 d (sheet text) | 46 | 52 | 65 | 20 | 19.67 / 20 | 2.5 / 3.2; 6.3 |
| DIN 938 | M24 | 3 | ≈ 1 d (sheet text) | 54 | 60 | 73 | 24 | 23.67 / 24 | 3.0 / 3.8; 7.5 |
| DIN 938 | M27 | 3 | ≈ 1 d (sheet text) | 60 | 66 | 79 | 25 | 26.67 / 27 | 3.0 / 3.8; 7.5 |
| DIN 938 | M30 | 3.5 | ≈ 1 d (sheet text) | 66 | 72 | 85 | 30 | 29.67 / 30 | 3.5 / 4.5; 9 |
| DIN 939 | M6 | 1 | 7.5 | 18 | 24 | – | — | — | — |
| DIN 939 | M8 | 1.25 | 10 | 22 | 28 | – | — | — | — |
| DIN 939 | M10 | 1.5 | 12 | 26 | 32 | 45 | — | — | — |
| DIN 939 | M12 | 1.75 | 15 | 30 | 36 | 49 | — | — | — |
| DIN 939 | M16 | 2 | 20 | 38 | 44 | 57 | — | — | — |
| DIN 939 | M20 | 2.5 | 25 | 46 | 52 | 65 | — | — | — |
| DIN 939 | M24 | 3 | 30 | 54 | 60 | 73 | — | — | — |
| DIN 939 | M27 | 3 | 35 | 60 | 66 | 79 | — | — | — |

## Where the files are

- Böllhoff: [DIN 938 stud, steel 5.8, metric coarse thread, threaded end ~ 1 d: thread length by length band, ds, z1, z2, pitch, available lengths 22 to 200 mm](https://eshop-cz.boellhoff.com/out/media/pdf/DIN_938_Stahl_5.8___en.pdf) — web — Maker data sheet; numbers only
- Böllhoff: [DIN 939 stud, steel 5.8, metric coarse thread, threaded end ~ 1.25 d: b1, thread length by length band, lengths 25 to 200 mm with tolerances](https://eshop-cz.boellhoff.com/out/media/pdf/DIN_939_Stahl_5.8___en.pdf) — web — Maker data sheet; numbers only
- fasten.it: [DIN 939 Standard Dimensions for studs with engagement length ~1.25 d (scope, ranges only; the table itself was not reproducible)](https://fasten.it/norms/norm/din_939) — web — Reference page; scope text only

## Questions

**What is the difference between DIN 938 and DIN 939?**

The screw-in end: about 1 × d for DIN 938 (steel into steel) and about 1.25 × d for DIN 939 (cast iron); Böllhoff prints DIN 939 b1 of 7.5 mm at M6 and 15 mm at M12.

**How long is the nut end of an M10 stud?**

26 mm for lengths up to 125 mm, 32 mm up to 200 mm and 45 mm above 200 mm on both Böllhoff sheets.

**What lengths do DIN 938 studs come in?**

22, 25, 28, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, 105, 110, 115, 120, 125, 130, 135, 140, 150, 160, 170, 180, 190, 200 mm on the Böllhoff sheet.

## Fits with

- [Threaded rod, metric M3 to M12 (DIN 976), 100 to 1000 mm](https://xemstudio.com/objects/threaded-rod-metric-din-976/)
- [Hex nuts, M2–M8 (ISO 4032)](https://xemstudio.com/objects/hex-nuts-metric/)
- [Hex nuts, M10 to M24 (ISO 4032 / DIN 934)](https://xemstudio.com/objects/hex-nuts-metric-m10-m24/)
- [Flat washers, M2–M8 (ISO 7089)](https://xemstudio.com/objects/flat-washers-metric/)
- [Socket head cap screws, M2–M8 (ISO 4762 / DIN 912)](https://xemstudio.com/objects/socket-head-cap-screws-metric/)
- [Hex head screws, M3–M8 (ISO 4017)](https://xemstudio.com/objects/hex-head-screws-metric/)