17 mm spanner
17.00 mm · 0.67 in
17 mm across the flats · fits a M10 (DIN 933) hex head
The nearest imperial size
11/16″ is 17.46 mm — 0.46 mm larger than 17 mm.
That is not close enough. Putting 11/16″ on a 17 mm head leaves 0.46 mm of slack, so the tool bears on the corners rather than the flats. On anything tight the corners round off, and once they do the fastener needs cutting out. This is the most common way a bolt is destroyed in a home garage.
The numbers
| Across flats | 17.00 mm · 0.67 in |
| Nearest imperial | 11/16″ — 17.46 mm |
| Difference | 0.46 mm — not safe to substitute |
| Fits | M10 (DIN 933) hex head |
Nearby metric sizes
| Size | mm | Nearest imperial | Gap |
|---|---|---|---|
| 14 mm | 14.00 | 9/16″ | 0.29 mm — do not |
| 15 mm | 15.00 | 9/16″ | 0.71 mm — do not |
| 16 mm | 16.00 | 5/8″ | 0.13 mm — swap |
| 17 mm | 17.00 | 11/16″ | 0.46 mm — do not |
| 18 mm | 18.00 | 11/16″ | 0.54 mm — do not |
| 19 mm | 19.00 | 3/4″ | 0.05 mm — swap |
Frequently asked questions
What is 17 mm in inches?
0.67 inches. The nearest imperial spanner is 11/16″ at 17.46 mm, 0.46 mm larger.
Can I use 11/16″ instead of 17 mm?
Not safely. The gap is 0.46 mm. 11/16″ is larger than 17 mm, so it sits on the corners of the head instead of the flats and rounds them off — this is how fasteners are destroyed.
What bolt does a 17 mm spanner fit?
A M10 (DIN 933) hex head. The full metric thread chart gives the tapping drill and clearance hole for it too.