7 mm spanner
7.00 mm · 0.28 in
7 mm across the flats · fits a M4 hex head
The nearest imperial size
1/4″ is 6.35 mm — 0.65 mm smaller than 7 mm.
That is not close enough. 1/4″ is smaller than the 7 mm head, so it will not go on at all — which is the harmless failure of the two.
The numbers
| Across flats | 7.00 mm · 0.28 in |
| Nearest imperial | 1/4″ — 6.35 mm |
| Difference | 0.65 mm — not safe to substitute |
| Fits | M4 hex head |
Nearby metric sizes
| Size | mm | Nearest imperial | Gap |
|---|---|---|---|
| 5.5 mm | 5.50 | 1/4″ | 0.85 mm — do not |
| 6 mm | 6.00 | 1/4″ | 0.35 mm — do not |
| 7 mm | 7.00 | 1/4″ | 0.65 mm — do not |
| 8 mm | 8.00 | 5/16″ | 0.06 mm — swap |
| 9 mm | 9.00 | 3/8″ | 0.52 mm — do not |
| 10 mm | 10.00 | 3/8″ | 0.48 mm — do not |
Frequently asked questions
What is 7 mm in inches?
0.28 inches. The nearest imperial spanner is 1/4″ at 6.35 mm, 0.65 mm smaller.
Can I use 1/4″ instead of 7 mm?
Not safely. The gap is 0.65 mm. 1/4″ is smaller than 7 mm and simply will not go on.
What bolt does a 7 mm spanner fit?
A M4 hex head. The full metric thread chart gives the tapping drill and clearance hole for it too.