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All-Metal Flange Lock Nut Dimensions (ISO 7044, M5 to M20)

Guide · Updated October 28, 2026

ISO 7044 covers prevailing torque type all-metal hexagon nuts with flange, style 2, with metric coarse thread from M5 to M20, grade A through M16 and grade B for M20, property classes 8, 9, 10 and 12. Hex, flange and bearing face match ISO 4161 plus an all-metal locking feature. Values come from the ISO 7044:2012 preview table, checked against the GlobalFastener ISO 7044 table and the Nufast ISO 7044 production drawing (every column, every size), with s, e, h, m and dc also matching the Fasten.it ISO 7044 table. One minor conflict: Nufast lists M20 flange diameter dc max as 42.90 mm while ISO, GlobalFastener and Fasten.it list 42.8 mm; we show 42.8. Not shown: da, c and r. For fine pitch, see ISO 12126.

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Step by step

Confirm coarse thread: ISO 7044 is coarse pitch: M6x1, M8x1.25, M10x1.5, M12x1.75, M16x2, M20x2.5. For fine pitch use ISO 12126.
Pick the wrench: Same hex as ISO 4161: M5 8 mm, M6 10 mm, M8 13 mm, M10 15 mm, M12 18 mm, M16 24 mm, M20 30 mm.
Check the flange: dc max is the clearance you need around the hole: M8 17.9 mm, M12 26.0 mm, M16 34.5 mm. No washer is needed.
Use total height for length: h max includes the locking crown: M8 9.40 mm, M12 13.80 mm. Use h max for bolt length math.
Leave thread past the nut: Run at least 2 full threads past the top so the deformed locking threads are fully engaged.
Pick it for heat: All-metal lock nuts have no nylon, so they suit hot spots like exhausts where a nylon insert (ISO 7043) would soften.

ISO 7044 all-metal flange lock nut dimensions (mm)

Columns: thread size x pitch, width across flats s max and min (s max is the wrench size), total height h max and min, thread height m min, wrenching height mw min, width across corners e min, flange diameter dc max, bearing face diameter dw min. Sizes in parentheses should be avoided if possible.

Size | s max | s min | h max | h min | m min | mw min | e min | dc max | dw min
M5x0.8 | 8.00 | 7.78 | 6.20 | 5.70 | 4.70 | 2.5 | 8.79 | 11.8 | 9.8
M6x1 | 10.00 | 9.78 | 7.30 | 6.80 | 5.70 | 3.1 | 11.05 | 14.2 | 12.2
M8x1.25 | 13.00 | 12.73 | 9.40 | 8.74 | 7.64 | 4.6 | 14.38 | 17.9 | 15.8
M10x1.5 | 15.00 | 14.73 | 11.40 | 10.34 | 9.64 | 5.6 | 16.64 | 21.8 | 19.6
M12x1.75 | 18.00 | 17.73 | 13.80 | 12.57 | 11.57 | 6.8 | 20.03 | 26.0 | 23.8
(M14x2) | 21.00 | 20.67 | 15.90 | 14.80 | 13.30 | 7.7 | 23.36 | 29.9 | 27.6
M16x2 | 24.00 | 23.67 | 18.30 | 17.20 | 15.30 | 8.9 | 26.75 | 34.5 | 31.9
M20x2.5 | 30.00 | 29.16 | 22.40 | 20.30 | 18.70 | 10.7 | 32.95 | 42.8 | 39.9

All-metal vs nylon vs plain flange nut

For M12 all three take an 18 mm wrench and have a 26.0 mm flange. Height max: ISO 4161 plain 12.00 mm, ISO 7044 all-metal 13.80 mm, ISO 7043 nylon insert 16.10 mm. A slightly oval or crimped top with no nylon ring means all-metal.

Worked example: bolt length for an M8 all-metal flange lock nut

Grip 12 mm, nut h max 9.40 mm, plus 2 threads at 1.25 mm = 2.5 mm. Total 23.9 mm, so an M8 x 25 works.

Common problems

Fine bolt, coarse nut: it starts, then binds. Check pitch first.
Galling: all-metal lock nuts on stainless bolts can seize. Lubricate and run them on slowly.
Reuse: prevailing torque drops after each use. Replace nuts on critical joints.

FAQ

What is the difference between ISO 7044 and ISO 7043?

Both are coarse thread hex flange lock nuts with the same hex and flange. ISO 7044 locks with deformed metal threads; ISO 7043 uses a nylon insert and is taller (M12 h max 13.80 mm vs 16.10 mm).

What is the difference between ISO 7044 and ISO 12126?

Both are all-metal hex flange lock nuts with the same hex and flange. ISO 7044 is coarse thread (M12x1.75); ISO 12126 is fine pitch (M12x1.5 or M12x1.25).

What is the difference between ISO 7044 and ISO 7042?

ISO 7042 is an all-metal lock nut without a flange. ISO 7044 has a built-in flange that spreads load like a washer. The hex differs at M10 (ISO 7044 15 mm, ISO 7042 16 mm).

What is the difference between ISO 7044 and ISO 4161?

ISO 4161 is the plain hex flange nut with no locking feature. ISO 7044 has the same hex, flange and bearing face plus an all-metal prevailing torque element, so it is a little taller (M12 13.80 mm vs 12.00 mm max).

What wrench fits an M10 all-metal flange lock nut?

15 mm for ISO 7044. ISO flange nuts use 15 mm at M10, not 16 or 17 mm.

How tall is an M8 all-metal flange lock nut?

9.40 mm max overall (8.74 mm min), with at least 7.64 mm of thread height.

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