H9 tolerance (hole, IT9)
Hole tolerance class H9 per ISO 286-1:2010: fundamental deviation EI = 0, grade IT9 (25 µm at ≤ 3 mm to 155 µm at 400–500 mm). For an exact size, open the calculator with H9 selected.
- Type
- Hole
- Grade
- IT9
- Tolerance
- 25 … 155 µm
- Fund. deviation
- EI = 0
H9 limits by size range
| Size (mm) | Upper (µm) | Lower (µm) | Ø max (mm) | Ø min (mm) | Upper (mm) | Lower (mm) | Dev. (in) |
|---|---|---|---|---|---|---|---|
| ≤ 3 | +25 | 0 | 3.025 | 3.000 | +0.025 | 0 | +0.00098 / 0 |
| 3 – 6 | +30 | 0 | 6.030 | 6.000 | +0.030 | 0 | +0.00118 / 0 |
| 6 – 10 | +36 | 0 | 10.036 | 10.000 | +0.036 | 0 | +0.00142 / 0 |
| 10 – 14 | +43 | 0 | 14.043 | 14.000 | +0.043 | 0 | +0.00169 / 0 |
| 14 – 18 | +43 | 0 | 18.043 | 18.000 | +0.043 | 0 | +0.00169 / 0 |
| 18 – 24 | +52 | 0 | 24.052 | 24.000 | +0.052 | 0 | +0.00205 / 0 |
| 24 – 30 | +52 | 0 | 30.052 | 30.000 | +0.052 | 0 | +0.00205 / 0 |
| 30 – 40 | +62 | 0 | 40.062 | 40.000 | +0.062 | 0 | +0.00244 / 0 |
| 40 – 50 | +62 | 0 | 50.062 | 50.000 | +0.062 | 0 | +0.00244 / 0 |
| 50 – 65 | +74 | 0 | 65.074 | 65.000 | +0.074 | 0 | +0.00291 / 0 |
| 65 – 80 | +74 | 0 | 80.074 | 80.000 | +0.074 | 0 | +0.00291 / 0 |
| 80 – 100 | +87 | 0 | 100.087 | 100.000 | +0.087 | 0 | +0.00343 / 0 |
| 100 – 120 | +87 | 0 | 120.087 | 120.000 | +0.087 | 0 | +0.00343 / 0 |
| 120 – 140 | +100 | 0 | 140.100 | 140.000 | +0.100 | 0 | +0.00394 / 0 |
| 140 – 160 | +100 | 0 | 160.100 | 160.000 | +0.100 | 0 | +0.00394 / 0 |
| 160 – 180 | +100 | 0 | 180.100 | 180.000 | +0.100 | 0 | +0.00394 / 0 |
| 180 – 200 | +115 | 0 | 200.115 | 200.000 | +0.115 | 0 | +0.00453 / 0 |
| 200 – 225 | +115 | 0 | 225.115 | 225.000 | +0.115 | 0 | +0.00453 / 0 |
| 225 – 250 | +115 | 0 | 250.115 | 250.000 | +0.115 | 0 | +0.00453 / 0 |
| 250 – 280 | +130 | 0 | 280.130 | 280.000 | +0.130 | 0 | +0.00512 / 0 |
| 280 – 315 | +130 | 0 | 315.130 | 315.000 | +0.130 | 0 | +0.00512 / 0 |
| 315 – 355 | +140 | 0 | 355.140 | 355.000 | +0.140 | 0 | +0.00551 / 0 |
| 355 – 400 | +140 | 0 | 400.140 | 400.000 | +0.140 | 0 | +0.00551 / 0 |
| 400 – 450 | +155 | 0 | 450.155 | 450.000 | +0.155 | 0 | +0.00610 / 0 |
| 450 – 500 | +155 | 0 | 500.155 | 500.000 | +0.155 | 0 | +0.00610 / 0 |
Deviations at the upper end of each range (Ø columns use that size); use the calculator for the exact size. — : not defined by ISO 286 for that size. Upper/Lower (mm) and inch columns are shown on wider screens.
About H9
H9 denotes a hole tolerance zone with zero line deviation in the ISO 286 system. It is used in H9/d9 (Shafts running in plain bearings with wide temperature variation, high speed or heavy journal pressure.) and H9/e9 (Plain bearings with ample lubrication, multi-bearing shafts, long bushes.).
At Ø25 mm H9 is +0.052 / 0 mm, i.e. 25.000 to 25.052 mm.
How the limits are calculated
H9 uses grade IT9 (a standard tolerance of 52 µm at 18–30 mm). Fundamental deviation: EI = 0: the tolerance zone sits entirely above the nominal size, and IT9 sets its width. See the fundamental deviation table for every letter. Values per ISO 286-1:2010.