Upper and lower deviations of hole H8 for nominal sizes 0–500 mm, per ISO 286-1. Values in mm; "+" means larger than nominal, "-" smaller. Calculate other sizes →
| Nominal size (mm) | Upper deviation | Lower deviation | Tolerance (IT) |
|---|---|---|---|
| 0 ~ 3 | +0.014 | 0 | 0.014 |
| >3 ~ 6 | +0.018 | 0 | 0.018 |
| >6 ~ 10 | +0.022 | 0 | 0.022 |
| >10 ~ 18 | +0.027 | 0 | 0.027 |
| >18 ~ 30 | +0.033 | 0 | 0.033 |
| >30 ~ 50 | +0.039 | 0 | 0.039 |
| >50 ~ 80 | +0.046 | 0 | 0.046 |
| >80 ~ 120 | +0.054 | 0 | 0.054 |
| >120 ~ 180 | +0.063 | 0 | 0.063 |
| >180 ~ 250 | +0.072 | 0 | 0.072 |
| >250 ~ 315 | +0.081 | 0 | 0.081 |
| >315 ~ 400 | +0.089 | 0 | 0.089 |
| >400 ~ 500 | +0.097 | 0 | 0.097 |
Each row applies to the whole size range shown. Ranges are "over the first value, up to and including the second".
H8 is an ISO 286 tolerance class. The uppercase letter H is the fundamental deviation (which side of the nominal size the tolerance zone lies on), and the number 8 is the tolerance grade IT8 (how wide the zone is). Basic hole (zero-clearance sliding): The lower deviation is 0, so the hole is never smaller than nominal. It is the datum of the hole-basis system; holes made with reamers and drills are naturally H. H7 is the most common hole tolerance: dowel pin holes, bushing bores, bearing housings. Typical processes for IT8: turning, reaming, milling, broaching: fits of ordinary accuracy (H8, f7).
On a drawing or in a specification, Ø6 H8 and 6(+0.018/0) mean the same thing — the second form writes the deviations out, so nobody has to look them up. SFP product specifications always use the second form.
Click "Calc" in the last column to open the calculator, where the written-out form can be copied with one click.
| Size | Upper deviation | Lower deviation | Actual limits (mm) | |
|---|---|---|---|---|
| Ø1 | +0.014 | 0 | 1.000 ~ 1.014 | Calc |
| Ø1.5 | +0.014 | 0 | 1.500 ~ 1.514 | Calc |
| Ø2 | +0.014 | 0 | 2.000 ~ 2.014 | Calc |
| Ø2.5 | +0.014 | 0 | 2.500 ~ 2.514 | Calc |
| Ø3 | +0.014 | 0 | 3.000 ~ 3.014 | Calc |
| Ø4 | +0.018 | 0 | 4.000 ~ 4.018 | Calc |
| Ø5 | +0.018 | 0 | 5.000 ~ 5.018 | Calc |
| Ø6 | +0.018 | 0 | 6.000 ~ 6.018 | Calc |
| Ø8 | +0.022 | 0 | 8.000 ~ 8.022 | Calc |
| Ø10 | +0.022 | 0 | 10.000 ~ 10.022 | Calc |
| Ø12 | +0.027 | 0 | 12.000 ~ 12.027 | Calc |
| Ø13 | +0.027 | 0 | 13.000 ~ 13.027 | Calc |
| Ø16 | +0.027 | 0 | 16.000 ~ 16.027 | Calc |
| Ø20 | +0.033 | 0 | 20.000 ~ 20.033 | Calc |
| Ø25 | +0.033 | 0 | 25.000 ~ 25.033 | Calc |
| Ø30 | +0.033 | 0 | 30.000 ~ 30.033 | Calc |
| Ø35 | +0.039 | 0 | 35.000 ~ 35.039 | Calc |
| Ø40 | +0.039 | 0 | 40.000 ~ 40.039 | Calc |
| Ø50 | +0.039 | 0 | 50.000 ~ 50.039 | Calc |
| Ø60 | +0.046 | 0 | 60.000 ~ 60.046 | Calc |
| Ø80 | +0.046 | 0 | 80.000 ~ 80.046 | Calc |
| Ø100 | +0.054 | 0 | 100.000 ~ 100.054 | Calc |
| Fit | Type | Typical use |
|---|---|---|
| H8/f7 | Clearance | Close running fit of ordinary accuracy; used like H7/f7 but with a less demanding hole: shafts and bushings in general machinery, pump and fan shafts. |
| H8/h7 | Clearance | Locational fit of ordinary accuracy with zero minimum clearance. Dowel pins and holes without high accuracy demands, removable sleeves. |
| H8/h8 | Clearance | Zero-clearance sliding fit of ordinary accuracy, hole and shaft of the same grade. Non-critical locating and guiding. |
| H8/e8 | Clearance | Easy running fit. High-speed or multi-bearing shafts, long shafts with wide spans, plain bearings that need a thicker oil film. |
The tolerance zones of the classes below lie entirely inside H8 (true for every size range from 0 to 500 mm), so they also satisfy a drawing that calls for H8. Those listed first are closest to H8; price and lead time still depend on material, size and stock.
It depends on the diameter. For Ø6, H8 means the part must measure between 6.000 and 6.018 mm, written 6(+0.018/0). For other diameters see the chart above; every size range is listed.
Letters in uppercase denote a hole (inside diameter). In lowercase, h8 is a shaft tolerance, lying on the opposite side of the nominal size.
Yes. H7 is tighter than H8: at every diameter its limits fall inside the range H8 allows. The precision is simply higher than required, so the price may be a little higher.
Values follow ISO 286-1; the table was cross-checked cell by cell against three independent sources on 2026-08-26 (6,674 cells agree, 0 errors). Coverage: shafts a–z and the corresponding uppercase holes, IT1–IT13, nominal sizes 0–500 mm. cd/ef/fg/za/zb/zc, sizes above 500 mm and grades above IT13 are not included: the tool reports "not found" and never extrapolates. Data sources and verification →