Tolerance chart
h9 tolerance (shaft): ISO 286 chart up to 500 mm
h9 is an ISO tolerance class for shafts (external features) under ISO 286. At Ø25 mm it means 0 / −52 µm: the size may lie between 24.948 and 25.000 mm. Below are the deviations for every nominal size up to 500 mm and the fits that use h9.
h9 chart: deviations for all nominal sizes up to 500 mm
Deviations in µm (1 µm = 0.001 mm). A nominal size belongs to the row »over … up to and including …«: exactly 30 mm is in the row ending at 30, 30.1 mm in the next one.
| Nominal size over – to (mm) | Upper deviation | Lower deviation | Tolerance |
|---|---|---|---|
| 0 – 3 | 0 | −25 | 25 |
| 3 – 6 | 0 | −30 | 30 |
| 6 – 10 | 0 | −36 | 36 |
| 10 – 18 | 0 | −43 | 43 |
| 18 – 30 | 0 | −52 | 52 |
| 30 – 50 | 0 | −62 | 62 |
| 50 – 80 | 0 | −74 | 74 |
| 80 – 120 | 0 | −87 | 87 |
| 120 – 180 | 0 | −100 | 100 |
| 180 – 250 | 0 | −115 | 115 |
| 250 – 315 | 0 | −130 | 130 |
| 315 – 400 | 0 | −140 | 140 |
| 400 – 500 | 0 | −155 | 155 |
h9 for your nominal size
How h9 is built
An ISO tolerance class is a letter and a number. Capital letters stand for holes, small letters for shafts. The letter h sets the position of the tolerance zone; at Ø25 mm it lies from the nominal size downwards: the shaft is never larger than nominal. The number 9 is the standard tolerance grade IT9: it sets how wide the zone is – 52 µm at Ø25 mm.
The tolerance grows with the nominal size: 25 µm in the smallest row (0 – 3 mm), 155 µm in the largest (400 – 500 mm). On a drawing the class follows the dimension, as in »Ø25 h9«; the inspection plan turns that into the limits 24.948 and 25.000 mm.
Fits with h9 at Ø25 mm
Shaft-basis system: the shaft stays h9, the hole changes. Clearance in µm; a minus means interference. Sorted from the largest minimum clearance to the largest interference.
| Fit | Type | Max. clearance | Min. clearance |
|---|---|---|---|
| D9/h9 | clearance fit | 169 | 65 |
| D10/h9 | clearance fit | 201 | 65 |
| E9/h9 | clearance fit | 144 | 40 |
| H9/h9 | clearance fit | 104 | 0 |
| H10/h9 | clearance fit | 136 | 0 |
Frequently asked questions about h9
What does h9 mean?
h9 is an ISO tolerance class for shafts (external features): the letter h sets the position of the tolerance zone, the number 9 the standard tolerance grade IT9. At Ø25 mm that gives 0 / −52 µm, i.e. 24.948 to 25.000 mm.
What are the h9 limits at Ø10 and Ø50 mm?
Ø10 h9: 0 / −36 µm (9.964 to 10.000 mm). Ø50 h9: 0 / −62 µm (49.938 to 50.000 mm).
Is h9 a clearance fit?
A tolerance class on its own is not a fit – only together with its mating part. H10/h9 at Ø25 mm is a clearance fit (maximum clearance 136 µm, minimum clearance 0 µm; a minus means interference).
More tolerance classes
Same letter h, other grades: h5 · h6 · h7 · h8 · h11
Shafts in grade 9: d9
All classes at a glance: ISO 286 tolerance charts. The same chart in German: h9 Toleranz.