1-1/16″ spanner
26.99 mm · 1.06 in
1-1/16″ across the flats
The nearest metric size
27 mm is 27.00 mm — 0.01 mm larger than 1-1/16″.
That is close enough to be interchangeable. 0.01 mm is well inside the manufacturing tolerance of the fastener, and the two will feel identical in use.
The numbers
| Across flats | 26.99 mm · 1.06 in |
| Nearest metric | 27 mm — 27.00 mm |
| Difference | 0.01 mm — interchangeable |
Nearby imperial sizes
| Size | mm | Nearest metric | Gap |
|---|---|---|---|
| 15/16″ | 23.81 | 24 mm | 0.19 mm |
| 1″ | 25.40 | 24 mm | 1.40 mm — do not |
| 1-1/16″ | 26.99 | 27 mm | 0.01 mm — swap |
| 1-1/8″ | 28.57 | 30 mm | 1.43 mm — do not |
Frequently asked questions
What is 1-1/16″ in millimetres?
26.99 mm. The nearest metric spanner is 27 mm — 0.01 mm larger.
Can I use 27 mm instead of 1-1/16″?
Yes. They are 0.01 mm apart, which is inside the tolerance of the fastener itself — these two are interchangeable in practice and most mechanics never notice they own both.
Where is 1-1/16″ used?
Imperial spanner sizes are "across flats" measurements and are still standard on American vehicles, plumbing and older machinery everywhere.