← AskMachinist · Guides · Calculator · 🔎 Search

Metric Jam Nut Size Chart (ISO 4035 Thin Nuts, M3 to M36)

Guide · Updated October 28, 2026

ISO 4035 covers hexagon thin nuts, style 0, often called jam nuts or lock nuts. They share the wrench size of the full ISO 4032 nut but are about half as tall. It replaced DIN 439. The table gives thread pitch, width across flats s, minimum width across corners e and nut height m from M3 to M36. Values agree between the ISO 4035:2023 preview, the Boltport ISO 4035 table and the Nufast ISO 4035 production drawing. Check the current edition or your supplier for critical work.

Need an exact reference size?

Build any gage block stack with the free Gage Block Calculator. Free, no login.

Step by step

Read the thread: Check the bolt diameter and pitch with a thread pitch gage. M12 coarse is 1.75 mm.
Find s: A thin nut uses the same wrench size as the full ISO 4032 nut: M8 13 mm, M10 16 mm, M12 18 mm.
Check height m: ISO 4035 style 0 nuts are about half height: m max is 0.5 × d (M10 5.0 mm, M20 10.0 mm).
Know the load limit: Thin nuts strip at a lower load than the bolt. Do not use one alone where the joint carries full preload.
Lock it right: Run the thin nut on first, then the full nut. Hold the full nut and back the thin nut against it to jam the threads.
Check engagement: Leave one to two full threads showing past the outer nut.

ISO 4035 thin nut dimensions (mm)

Columns are: thread size, coarse pitch P, s max (nominal wrench size), s min, e min, m max and m min. M14, M18, M22, M27 and M33 are non-preferred sizes. Product grade A covers up to M16 and grade B from M18. M3 and M4 are in Annex A of the 2023 edition.

Size | P | s max | s min | e min | m max | m min
M3 | 0.5 | 5.50 | 5.32 | 6.01 | 1.80 | 1.55
M4 | 0.7 | 7.00 | 6.78 | 7.66 | 2.20 | 1.95
M5 | 0.8 | 8.00 | 7.78 | 8.79 | 2.70 | 2.45
M6 | 1 | 10.00 | 9.78 | 11.05 | 3.20 | 2.90
M8 | 1.25 | 13.00 | 12.73 | 14.38 | 4.00 | 3.70
M10 | 1.5 | 16.00 | 15.73 | 17.77 | 5.00 | 4.70
M12 | 1.75 | 18.00 | 17.73 | 20.03 | 6.00 | 5.70
M14 | 2 | 21.00 | 20.67 | 23.36 | 7.00 | 6.42
M16 | 2 | 24.00 | 23.67 | 26.75 | 8.00 | 7.42
M18 | 2.5 | 27.00 | 26.16 | 29.56 | 9.00 | 8.42
M20 | 2.5 | 30.00 | 29.16 | 32.95 | 10.00 | 9.10
M22 | 2.5 | 34.00 | 33.00 | 37.29 | 11.00 | 9.90
M24 | 3 | 36.00 | 35.00 | 39.55 | 12.00 | 10.90
M27 | 3 | 41.00 | 40.00 | 45.20 | 13.50 | 12.40
M30 | 3.5 | 46.00 | 45.00 | 50.85 | 15.00 | 13.90
M33 | 3.5 | 50.00 | 49.00 | 55.37 | 16.50 | 15.40
M36 | 4 | 55.00 | 53.80 | 60.79 | 18.00 | 16.90

Thin nut vs full nut height

Compare m max for the same thread. M6: 3.2 thin vs 5.2 full. M8: 4.0 vs 6.8. M10: 5.0 vs 8.4. M12: 6.0 vs 10.8. M16: 8.0 vs 14.8. M20: 10.0 vs 18.0. M24: 12.0 vs 21.5. The thin nut is roughly 0.5 × d, the full ISO 4032 nut roughly 0.85 to 0.9 × d. Fewer engaged threads is why thin nuts are not rated for full bolt preload.

ISO 4035 vs DIN 439

DIN 439 B was the old thin nut standard. Heights match ISO 4035 for most sizes, but wrench sizes follow the same DIN-to-ISO change as full nuts: M10 17→16, M12 19→18, M14 22→21 and M22 32→34 mm. A 17 mm thin M10 nut is DIN 439, not ISO 4035.

Worked example: locking a lathe carriage stop

An M10 stop screw needs a jam nut. Use an ISO 4035 M10 thin nut, 16 mm flats and 5.0 mm tall. Set the screw, run the thin nut down to the bracket, then hold the screw with a hex key and snug the nut with a 16 mm wrench. For a stop that takes repeated hits, add a full M10 nut on top and jam the two together: hold the outer nut and back the inner nut up against it.

Worked example: how much thread do two nuts need?

An M12 rod gets a thin nut plus a full nut. Stack height is 6.0 + 10.8 = 16.8 mm max. Add two pitches (2 × 1.75 = 3.5 mm) showing past the outer nut, so leave at least 20.3 mm of threaded length beyond the part face, call it 21 mm.

Common problems

Jam nut loosens: both nuts were tightened in the same direction without jamming. Hold the outer nut and back the inner nut against it.
Thin nut strips: it was used alone under full preload. Use a full nut, or a full nut plus a thin nut.
Wrench sloppy on M10 thin nut: 17 mm on a 16 mm ISO nut. Switch wrenches.
No room for a thin nut: use a nylon insert lock nut (ISO 10511, also thin) or thread locker.

ISO 4035 vs ISO 4036 side by side (M3 to M10)

Both are thin hex nuts. ISO 4035 is chamfered, product grade A up to M16 (B above), and runs M3 to M36. ISO 4036 is unchamfered (style 0), grade B only, and stops at M10. Where sizes overlap, wrench size s max and height m are the same; the wider grade B tolerance shows up as a lower s min and e min on ISO 4036. Values below are copied from the two charts on this site (mm).

Size | s max | s min 4035 / 4036 | e min 4035 / 4036 | m max (both)
M3 | 5.50 | 5.32 / 5.20 | 6.01 / 5.88 | 1.80
M4 | 7.00 | 6.78 / 6.64 | 7.66 / 7.50 | 2.20
M5 | 8.00 | 7.78 / 7.64 | 8.79 / 8.63 | 2.70
M6 | 10.00 | 9.78 / 9.64 | 11.05 / 10.89 | 3.20
M8 | 13.00 | 12.73 / 12.57 | 14.38 / 14.20 | 4.00
M10 | 16.00 | 15.73 / 15.57 | 17.77 / 17.59 | 5.00

Which to pick: same wrench and same stack height, so they swap in a fixture. Choose ISO 4035 when you need a property class (04, 05), sizes above M10, or a chamfer that will not mark the part. Choose ISO 4036 for small instrument and adjuster lock nuts where cost matters and below M3 (M1.6 to M2.5 exist only in ISO 4036). Inspect s with a caliper against the lower s min for the grade you bought.

Sources: ISO 4035 chart and ISO 4036 chart.

FAQ

Is an ISO 4035 jam nut interchangeable with ISO 4036?

From M3 to M10, yes for fit: same wrench size and same height. ISO 4035 is chamfered and grade A with property classes 04 and 05; ISO 4036 is unchamfered grade B with no property class, so use 4035 where strength is specified.

What size wrench fits an M10 jam nut?

16 mm, the same as an ISO 4032 M10 full nut. Old DIN 439 M10 thin nuts are 17 mm.

How thick is an M8 jam nut?

ISO 4035 M8 height m is 3.70 to 4.00 mm, about 60% of the 6.80 mm full nut.

Does the jam nut go on first or second?

Strictly, the thin nut goes on first (against the part) and the full nut on top, because the outer nut carries the load once jammed. Many shops put the thin nut on top for looks; it still locks but the thin nut then carries the load.

Can I use a thin nut by itself?

Only for light loads such as adjuster lock-ups. ISO 4035 warns that thin nuts have lower thread stripping resistance than the bolt.

Related guides and calculators

Build your stack in seconds

The free Gage Block Calculator finds the fewest-block combination for inch and metric sets, with wear blocks. No login.

Questions? Ask a machinist.

General shop information only — follow your drawing, tool maker's data and your quality system.