Tolerance chart
h7 tolerance (shaft): ISO 286 chart up to 500 mm
h7 is an ISO tolerance class for shafts (external features) under ISO 286. At Ø25 mm it means 0 / −21 µm: the size may lie between 24.979 and 25.000 mm. Below are the deviations for every nominal size up to 500 mm and the fits that use h7.
h7 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 | −10 | 10 |
| 3 – 6 | 0 | −12 | 12 |
| 6 – 10 | 0 | −15 | 15 |
| 10 – 18 | 0 | −18 | 18 |
| 18 – 30 | 0 | −21 | 21 |
| 30 – 50 | 0 | −25 | 25 |
| 50 – 80 | 0 | −30 | 30 |
| 80 – 120 | 0 | −35 | 35 |
| 120 – 180 | 0 | −40 | 40 |
| 180 – 250 | 0 | −46 | 46 |
| 250 – 315 | 0 | −52 | 52 |
| 315 – 400 | 0 | −57 | 57 |
| 400 – 500 | 0 | −63 | 63 |
h7 for your nominal size
How h7 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 7 is the standard tolerance grade IT7: it sets how wide the zone is – 21 µm at Ø25 mm.
The tolerance grows with the nominal size: 10 µm in the smallest row (0 – 3 mm), 63 µm in the largest (400 – 500 mm). On a drawing the class follows the dimension, as in »Ø25 h7«; the inspection plan turns that into the limits 24.979 and 25.000 mm.
Fits with h7 at Ø25 mm
Shaft-basis system: the shaft stays h7, 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 |
|---|---|---|---|
| E8/h7 | clearance fit | 94 | 40 |
| F7/h7 | clearance fit | 62 | 20 |
| F8/h7 | clearance fit | 74 | 20 |
| G7/h7 | clearance fit | 49 | 7 |
| H7/h7 | clearance fit | 42 | 0 |
| H8/h7 | clearance fit | 54 | 0 |
| JS7/h7 | transition fit | 31.5 | −10.5 |
| K7/h7 | transition fit | 27 | −15 |
| M7/h7 | transition fit | 21 | −21 |
| N7/h7 | transition fit | 14 | −28 |
| P7/h7 | transition fit | 7 | −35 |
| R7/h7 | transition fit | 1 | −41 |
| S7/h7 | interference fit | −6 | −48 |
Frequently asked questions about h7
What does h7 mean?
h7 is an ISO tolerance class for shafts (external features): the letter h sets the position of the tolerance zone, the number 7 the standard tolerance grade IT7. At Ø25 mm that gives 0 / −21 µm, i.e. 24.979 to 25.000 mm.
What are the h7 limits at Ø10 and Ø50 mm?
Ø10 h7: 0 / −15 µm (9.985 to 10.000 mm). Ø50 h7: 0 / −25 µm (49.975 to 50.000 mm).
Is h7 a clearance fit?
A tolerance class on its own is not a fit – only together with its mating part. H8/h7 at Ø25 mm is a clearance fit (maximum clearance 54 µm, minimum clearance 0 µm; a minus means interference).
More tolerance classes
Same letter h, other grades: h5 · h6 · h8 · h9 · h11
All classes at a glance: ISO 286 tolerance charts. The same chart in German: h7 Toleranz.