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Hook Spanner Sizes (DIN 1810 Form A, 12 to 145 mm)
Guide · Updated October 28, 2026
DIN 1810 covers hook spanners (C spanners) for slotted round nuts. Form A, with a square nose, fits DIN 1804 slotted nuts and DIN 981 bearing lock nuts. Size range, length and thickness agree across the Hanser DIN 1810 table, the AMF DIN 1810A catalog page and the Mädler DIN 1810 A table from 16-20 to 95-100, and across AMF, Mädler and the Spaenaur DIN 1810 A catalog for 12-14 and 110-115 to 135-145. Spaenaur lists 242 mm for 58-62; the other three say 240 mm, so we used 240. Skipped: non-DIN in-between sizes (38-45, 65-70, 85-92), sizes from 155-165 up (length and thickness differ between catalogs). For pin-hole nuts (DIN 1816), see the DIN 1810 Form B pin spanner chart.
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Step by step
- Measure the nut: Measure the outside diameter of the slotted round nut across the slots, or read d2 from the DIN 1804 chart.
- Find the range: Pick the DIN 1810 size whose range covers that diameter, for example 45-50 for a 50 mm nut.
- Check the nose: Form A has a square nose for outside slots (DIN 1804, DIN 981). Form B has a round pin for pin-hole nuts (DIN 1816).
- Seat the hook: Put the nose fully into a slot with the hook arc lying on the nut, not riding up on the edge.
- Pull the right way: Pull so the hook closes onto the nut; pulling the other way lets it slip off.
- Check reach: Long handles give a lot of torque; do not add a cheater bar to the small sizes.
DIN 1810 form A hook spanner sizes (mm)
Columns: size (nut outside diameter range), overall length L, thickness T, DIN 1804 nuts it fits.
- Size | L | T | DIN 1804 nuts
- DIN 1810-A12-14 | 110 | 3 | -
- DIN 1810-A16-20 | 110 | 3 | M8x1
- DIN 1810-A25-28 | 136 | 4 | M10x1, M12x1.5
- DIN 1810-A30-32 | 136 | 4 | M14x1.5, M16x1.5
- DIN 1810-A34-36 | 170 | 5 | M18x1.5, M20x1.5
- DIN 1810-A40-42 | 170 | 5 | M22x1.5, M24x1.5
- DIN 1810-A45-50 | 206 | 6 | M26x1.5 to M30x1.5
- DIN 1810-A52-55 | 206 | 6 | M32x1.5, M35x1.5
- DIN 1810-A58-62 | 240 | 7 | M38x1.5 to M42x1.5
- DIN 1810-A68-75 | 240 | 7 | M45x1.5 to M50x1.5
- DIN 1810-A80-90 | 280 | 8 | M52x1.5 to M60x1.5
- DIN 1810-A95-100 | 280 | 8 | -
- DIN 1810-A110-115 | 335 | 10 | -
- DIN 1810-A120-130 | 335 | 10 | -
- DIN 1810-A135-145 | 385 | 10 | -
Worked example: M30x1.5 shaft nut
A DIN 1804 M30x1.5 nut is 50 mm across, so it takes the DIN 1810-A45-50 spanner: 206 mm long, 6 mm thick. The same spanner fits the M26x1.5 (45 mm) and M28x1.5 (50 mm) nuts.
Hook vs pin vs adjustable
- Form A hook: square nose for outside slots (DIN 1804, DIN 981).
- Form B pin: round pin for side pin holes (DIN 1816).
- Adjustable hook: one tool for many sizes, but a looser fit on the nut.
Common problems
- Spanner slips off: wrong range, or pulling the open way. Pull so the hook closes.
- Nose will not enter the slot: slot is narrow or burred; clean it up.
- Slot corners rounding: nose not fully seated; seat it before pulling.
FAQ
What is a DIN 1810 hook spanner?
A flat C-shaped wrench with a nose at the tip that drops into a slot on a round nut. It is also called a C spanner or hook wrench.
How do I read the size 45-50?
It is the range of nut outside diameters in mm the spanner fits: 45 to 50 mm. Each size covers a small range because the hook arc can flex slightly.
Form A or form B?
Form A has a square nose for slotted nuts like DIN 1804 and DIN 981 bearing nuts. Form B has a round pin for nuts with side pin holes like DIN 1816.
Why are there gaps like 21 to 24 mm?
The DIN size steps follow the common DIN 1804 nut diameters. Some makers sell in-between sizes such as 38-45, but those are not DIN sizes.
Why stop at 135-145?
Our sources agree on every value up to 135-145. Above that, thickness and length differ between catalogs, so we left those rows off.
Can one spanner fit two nut sizes?
Yes. A 25-28 spanner fits both the 25 mm M10x1 nut and the 28 mm M12x1.5 nut in DIN 1804.
Related guides and calculators
- Pin spanner sizes (DIN 1810 Form B)
- Slotted round nut dimensions (DIN 1804)
- Round nut with pin holes (DIN 1816)
- Thrust screw dimensions (DIN 6332)
- T-slot nut dimensions (DIN 508)
- All free machinist calculators
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