When to use H8/f7
More clearance than H7/f7: for shafts in plain bearings on general machines, where free running matters more than precision.
H8/f7 tolerances for every diameter
| Diameter (mm) | Hole H8 (µm) | Shaft f7 (µm) | Max clearance | Min clearance |
|---|---|---|---|---|
| ≤ 3 | +14 / 0 | -6 / -16 | +30 | +6 |
| 3–6 | +18 / 0 | -10 / -22 | +40 | +10 |
| 6–10 | +22 / 0 | -13 / -28 | +50 | +13 |
| 10–18 | +27 / 0 | -16 / -34 | +61 | +16 |
| 18–30 | +33 / 0 | -20 / -41 | +74 | +20 |
| 30–50 | +39 / 0 | -25 / -50 | +89 | +25 |
| 50–80 | +46 / 0 | -30 / -60 | +106 | +30 |
| 80–120 | +54 / 0 | -36 / -71 | +125 | +36 |
| 120–180 | +63 / 0 | -43 / -83 | +146 | +43 |
| 180–250 | +72 / 0 | -50 / -96 | +168 | +50 |
| 250–315 | +81 / 0 | -56 / -108 | +189 | +56 |
| 315–400 | +89 / 0 | -62 / -119 | +208 | +62 |
| 400–500 | +97 / 0 | -68 / -131 | +228 | +68 |
Negative clearance = interference: the shaft is larger than the hole. Values in micrometres (µm, thousandths of a millimetre). Diameter ranges: over the first value, up to and including the second.
Other fits
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.