h8 tolerance (shaft, IT8)
Shaft tolerance class h8 per ISO 286-1:2010: fundamental deviation es = 0, grade IT8 (14 µm at ≤ 3 mm to 97 µm at 400–500 mm). For an exact size, open the calculator with h8 selected.
- Type
- Shaft
- Grade
- IT8
- Tolerance
- 14 … 97 µm
- Fund. deviation
- es = 0
h8 limits by size range
| Size (mm) | Upper (µm) | Lower (µm) | Ø max (mm) | Ø min (mm) | Upper (mm) | Lower (mm) | Dev. (in) |
|---|---|---|---|---|---|---|---|
| ≤ 3 | 0 | −14 | 3.000 | 2.986 | 0 | −0.014 | 0 / −0.00055 |
| 3 – 6 | 0 | −18 | 6.000 | 5.982 | 0 | −0.018 | 0 / −0.00071 |
| 6 – 10 | 0 | −22 | 10.000 | 9.978 | 0 | −0.022 | 0 / −0.00087 |
| 10 – 14 | 0 | −27 | 14.000 | 13.973 | 0 | −0.027 | 0 / −0.00106 |
| 14 – 18 | 0 | −27 | 18.000 | 17.973 | 0 | −0.027 | 0 / −0.00106 |
| 18 – 24 | 0 | −33 | 24.000 | 23.967 | 0 | −0.033 | 0 / −0.00130 |
| 24 – 30 | 0 | −33 | 30.000 | 29.967 | 0 | −0.033 | 0 / −0.00130 |
| 30 – 40 | 0 | −39 | 40.000 | 39.961 | 0 | −0.039 | 0 / −0.00154 |
| 40 – 50 | 0 | −39 | 50.000 | 49.961 | 0 | −0.039 | 0 / −0.00154 |
| 50 – 65 | 0 | −46 | 65.000 | 64.954 | 0 | −0.046 | 0 / −0.00181 |
| 65 – 80 | 0 | −46 | 80.000 | 79.954 | 0 | −0.046 | 0 / −0.00181 |
| 80 – 100 | 0 | −54 | 100.000 | 99.946 | 0 | −0.054 | 0 / −0.00213 |
| 100 – 120 | 0 | −54 | 120.000 | 119.946 | 0 | −0.054 | 0 / −0.00213 |
| 120 – 140 | 0 | −63 | 140.000 | 139.937 | 0 | −0.063 | 0 / −0.00248 |
| 140 – 160 | 0 | −63 | 160.000 | 159.937 | 0 | −0.063 | 0 / −0.00248 |
| 160 – 180 | 0 | −63 | 180.000 | 179.937 | 0 | −0.063 | 0 / −0.00248 |
| 180 – 200 | 0 | −72 | 200.000 | 199.928 | 0 | −0.072 | 0 / −0.00283 |
| 200 – 225 | 0 | −72 | 225.000 | 224.928 | 0 | −0.072 | 0 / −0.00283 |
| 225 – 250 | 0 | −72 | 250.000 | 249.928 | 0 | −0.072 | 0 / −0.00283 |
| 250 – 280 | 0 | −81 | 280.000 | 279.919 | 0 | −0.081 | 0 / −0.00319 |
| 280 – 315 | 0 | −81 | 315.000 | 314.919 | 0 | −0.081 | 0 / −0.00319 |
| 315 – 355 | 0 | −89 | 355.000 | 354.911 | 0 | −0.089 | 0 / −0.00350 |
| 355 – 400 | 0 | −89 | 400.000 | 399.911 | 0 | −0.089 | 0 / −0.00350 |
| 400 – 450 | 0 | −97 | 450.000 | 449.903 | 0 | −0.097 | 0 / −0.00382 |
| 450 – 500 | 0 | −97 | 500.000 | 499.903 | 0 | −0.097 | 0 / −0.00382 |
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 h8
h8 denotes a shaft tolerance zone with zero line deviation in the ISO 286 system. It is used in H8/h8 (General-purpose sliding and locating fit for parts that need to move freely but stay aligned.) and H7/h8 (Looser again than H7/h7 for economical sliding and location where cost matters more than precision: sheet-metal brackets, low-duty pins and bushings, prototype fixtures.).
At Ø25 mm h8 is 0 / −0.033 mm, i.e. 24.967 to 25.000 mm.
How the limits are calculated
h8 uses grade IT8 (a standard tolerance of 33 µm at 18–30 mm). Fundamental deviation: es = 0: the tolerance zone sits entirely below the nominal size, and IT8 sets its width. See the fundamental deviation table for every letter. Values per ISO 286-1:2010.