h7 table
| Diameter (mm) | Upper (µm) | Lower (µm) | Example: limit sizes |
|---|---|---|---|
| ≤ 3 | 0 | -10 | Ø3: 2.990 – 3.000 |
| 3–6 | 0 | -12 | Ø6: 5.988 – 6.000 |
| 6–10 | 0 | -15 | Ø10: 9.985 – 10.000 |
| 10–18 | 0 | -18 | Ø18: 17.982 – 18.000 |
| 18–30 | 0 | -21 | Ø30: 29.979 – 30.000 |
| 30–50 | 0 | -25 | Ø50: 49.975 – 50.000 |
| 50–80 | 0 | -30 | Ø80: 79.970 – 80.000 |
| 80–120 | 0 | -35 | Ø120: 119.965 – 120.000 |
| 120–180 | 0 | -40 | Ø180: 179.960 – 180.000 |
| 180–250 | 0 | -46 | Ø250: 249.954 – 250.000 |
| 250–315 | 0 | -52 | Ø315: 314.948 – 315.000 |
| 315–400 | 0 | -57 | Ø400: 399.943 – 400.000 |
| 400–500 | 0 | -63 | Ø500: 499.937 – 500.000 |
How to read it
The letter tells where the tolerance zone sits relative to the nominal size, the number how wide it is (grade IT7). Capitals are for holes, lower case for shafts. With h the upper limit is always zero: the shaft is never larger than nominal.
Other classes
Values computed from the IT grades and fundamental deviations of ISO 286-1, checked against several published tables. For critical designs the standard itself is what counts.