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ISO fit tolerance lookup
Enter a nominal size and a grade and it returns the two deviations in microns and the two limit sizes in millimetres — the numbers you actually set the machine and the gauge to.
The reference below is free to read — no account, no signup. The tool itself is inside MechCircle, which is free to start.
H7 hole and h6 shaft, common sizes
| Nominal | H7 upper / lower | h6 upper / lower | H7 largest size |
|---|---|---|---|
| 10 mm | +15 / 0 µm | 0 / -9 µm | 10.015 mm |
| 20 mm | +21 / 0 µm | 0 / -13 µm | 20.021 mm |
| 30 mm | +21 / 0 µm | 0 / -13 µm | 30.021 mm |
| 50 mm | +25 / 0 µm | 0 / -16 µm | 50.025 mm |
The tool carries 38 shaft grades and 33 hole grades across ten size bands from 1 to 250 mm.
How to use it
Choose shaft or hole first, which filters the grade list to that side, so a lowercase h6 can never be picked when H7 was meant. The size band used is always named in the result, so you can see it landed in the right one.
What it does and does not cover
- Covers 1 mm to 250 mm.
- Where a grade is not defined for a size band the tool says so rather than guessing. Sixty-four such combinations exist and none of them is extrapolated.
- Band boundaries are inclusive at the top: 10.0 mm sits in the 6 to 10 band, not 10 to 18.
Ready to get started?
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