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Fine Thread Thin Hex Nut Dimensions (ISO 8675, M8x1 to M36x3)

Guide · Updated October 28, 2026

ISO 8675 covers hexagon thin nuts, style 0, with metric fine pitch thread, product grade A up to M16 and grade B from M18. Thin nuts are jam nuts: use them with a regular or high nut. Hex, corners and bearing face match ISO 8673 and ISO 8674; only the height is less. Values come from the ISO 8675:2023 preview tables (every size M8 to M39), checked against the Due Emme ISO 8675 table (s and m for every size and pitch), the Ganter ISO 8675 catalog (m and s for M8x1 to M24x2, e rounded to 0.1 mm) and the hex, corner and bearing face values on our ISO 8673 and 8674 charts. Wrenching height mw is from ISO and equals 0.8 x m min. Not shown: transition diameter da. Skipped: M39x3, because only one source lists its corner and bearing face sizes. One web table labeled ISO 8675 lists DIN 936 heights and hex sizes (for example M10 6 mm high, 17 mm hex); those do not match ISO 8675, so we did not use it.

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Step by step

Confirm fine pitch: Check pitch with a thread gage. An M12x1.5 thin nut will not run on a coarse M12x1.75 bolt, and M12x1.25 is not M12x1.5.
Pick the wrench: Same hex as ISO 8673 and ISO 8674: M8 13 mm, M10 16 mm, M12 18 mm, M16 24 mm, M20 30 mm, M24 36 mm.
Check the height: Thin nuts are about half the nominal diameter: M12 6.00 mm max, M20 10.00 mm max. Use m max for bolt length math.
Use it as a jam nut: Style 0 has reduced load capacity and is not designed to resist thread stripping. Pair it with a regular (ISO 8673) or high (ISO 8674) nut.
Tighten in order: Common practice: run the thin nut down first, set the full nut on top, then hold the full nut and back the thin nut against it.
Leave thread past the nut: Run at least 2 full threads past the outer nut face.

ISO 8675 fine thread thin hex nut dimensions (mm)

Columns: thread size x pitch, width across flats s max and min (s max is the wrench size), nut height m max, m min, wrenching height mw min, width across corners e min, bearing face diameter dw min. Sizes in parentheses are non-preferred in ISO 8675:2023.

Size | s max | s min | m max | m min | mw min | e min | dw min
M8x1 | 13.00 | 12.73 | 4.00 | 3.70 | 2.96 | 14.38 | 11.63
M10x1.25 / (M10x1) | 16.00 | 15.73 | 5.00 | 4.70 | 3.76 | 17.77 | 14.63
M12x1.5 / (M12x1.25) | 18.00 | 17.73 | 6.00 | 5.70 | 4.56 | 20.03 | 16.63
(M14x1.5) | 21.00 | 20.67 | 7.00 | 6.42 | 5.14 | 23.36 | 19.64
M16x1.5 | 24.00 | 23.67 | 8.00 | 7.42 | 5.94 | 26.75 | 22.49
(M18x2) / (M18x1.5) | 27.00 | 26.16 | 9.00 | 8.42 | 6.74 | 29.56 | 24.85
M20x2 / (M20x1.5) | 30.00 | 29.16 | 10.00 | 9.10 | 7.28 | 32.95 | 27.70
(M22x2) / (M22x1.5) | 34.00 | 33.00 | 11.00 | 9.90 | 7.92 | 37.29 | 31.35
M24x2 | 36.00 | 35.00 | 12.00 | 10.90 | 8.72 | 39.55 | 33.25
(M27x2) | 41.00 | 40.00 | 13.50 | 12.40 | 9.92 | 45.20 | 38.00
M30x2 | 46.00 | 45.00 | 15.00 | 13.90 | 11.12 | 50.85 | 42.75
(M33x2) | 50.00 | 49.00 | 16.50 | 15.40 | 12.32 | 55.37 | 46.55
M36x3 | 55.00 | 53.80 | 18.00 | 16.90 | 13.52 | 60.79 | 51.11

Thin vs regular vs high fine nut

For M16x1.5 all three take a 24 mm wrench. Height max: ISO 8675 thin 8.00 mm, ISO 8673 regular 14.80 mm, ISO 8674 high 16.40 mm. Measure height to tell them apart.

Worked example: bolt length for an M16x1.5 jam nut pair

Grip 25 mm, thin nut 8.00 mm, regular ISO 8673 nut 14.80 mm, plus 2 threads at 1.5 mm = 3.0 mm. Total 50.8 mm, so an M16x1.5 x 55 works.

Common problems

Thin nut used alone under load: it can strip. Add a full nut.
Coarse bolt, fine nut: it starts, then binds. Check pitch first.
Old DIN 439 stock with 17, 19 or 22 mm hex mixed with ISO 16, 18 or 21 mm stock. Check the wrench size.

FAQ

What is the difference between ISO 8675 and ISO 4035?

Same thin style 0 nut. ISO 8675 has metric fine pitch thread; ISO 4035 has coarse thread.

What is the difference between ISO 8675 and ISO 8673?

Same hex, corners and bearing face. ISO 8675 is much thinner: M12 6.00 vs 10.80 mm max, M20 10.00 vs 18.00 mm max.

What wrench fits an M16x1.5 thin nut?

24 mm.

How thick is an M20x1.5 ISO 8675 nut?

10.00 mm max, 9.10 mm min.

Can a thin nut carry full bolt load?

No. ISO 8675 style 0 nuts have reduced loadability (classes 04 and 05). Use them as jam or adjusting nuts, not as the only load-carrying nut.

Is ISO 8675 the same as DIN 439?

Close. DIN 439 B is the older fine thread thin nut. Some old DIN sizes use different hex widths (M10 17, M12 19, M14 22, M22 32 mm), so check the wrench size before mixing stock.

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