Tolerance chart
h6 tolerance (shaft): ISO 286 chart up to 500 mm
h6 is an ISO tolerance class for shafts (external features) under ISO 286. At Ø25 mm it means 0 / −13 µm: the size may lie between 24.987 and 25.000 mm. Below are the deviations for every nominal size up to 500 mm and the fits that use h6.
h6 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 | −6 | 6 |
| 3 – 6 | 0 | −8 | 8 |
| 6 – 10 | 0 | −9 | 9 |
| 10 – 18 | 0 | −11 | 11 |
| 18 – 30 | 0 | −13 | 13 |
| 30 – 50 | 0 | −16 | 16 |
| 50 – 80 | 0 | −19 | 19 |
| 80 – 120 | 0 | −22 | 22 |
| 120 – 180 | 0 | −25 | 25 |
| 180 – 250 | 0 | −29 | 29 |
| 250 – 315 | 0 | −32 | 32 |
| 315 – 400 | 0 | −36 | 36 |
| 400 – 500 | 0 | −40 | 40 |
h6 for your nominal size
How h6 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 6 is the standard tolerance grade IT6: it sets how wide the zone is – 13 µm at Ø25 mm.
The tolerance grows with the nominal size: 6 µm in the smallest row (0 – 3 mm), 40 µm in the largest (400 – 500 mm). On a drawing the class follows the dimension, as in »Ø25 h6«; the inspection plan turns that into the limits 24.987 and 25.000 mm.
Fits with h6 at Ø25 mm
Shaft-basis system: the shaft stays h6, 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 |
|---|---|---|---|
| F7/h6 | clearance fit | 54 | 20 |
| G6/h6 | clearance fit | 33 | 7 |
| G7/h6 | clearance fit | 41 | 7 |
| H6/h6 | clearance fit | 26 | 0 |
| H7/h6 | clearance fit | 34 | 0 |
| JS6/h6 | transition fit | 19.5 | −6.5 |
| JS7/h6 | transition fit | 23.5 | −10.5 |
| K6/h6 | transition fit | 15 | −11 |
| K7/h6 | transition fit | 19 | −15 |
| M6/h6 | transition fit | 9 | −17 |
| M7/h6 | transition fit | 13 | −21 |
| N6/h6 | transition fit | 2 | −24 |
| N7/h6 | transition fit | 6 | −28 |
| P6/h6 | interference fit | −5 | −31 |
| P7/h6 | interference fit | −1 | −35 |
| R7/h6 | interference fit | −7 | −41 |
| S7/h6 | interference fit | −14 | −48 |
Frequently asked questions about h6
What does h6 mean?
h6 is an ISO tolerance class for shafts (external features): the letter h sets the position of the tolerance zone, the number 6 the standard tolerance grade IT6. At Ø25 mm that gives 0 / −13 µm, i.e. 24.987 to 25.000 mm.
What are the h6 limits at Ø10 and Ø50 mm?
Ø10 h6: 0 / −9 µm (9.991 to 10.000 mm). Ø50 h6: 0 / −16 µm (49.984 to 50.000 mm).
Is h6 a clearance fit?
A tolerance class on its own is not a fit – only together with its mating part. H7/h6 at Ø25 mm is a clearance fit (maximum clearance 34 µm, minimum clearance 0 µm; a minus means interference).
More tolerance classes
Same letter h, other grades: h5 · h7 · h8 · h9 · h11
Shafts in grade 6: g6 · f6 · js6 · k6 · m6 · n6 · p6 · r6 · s6
All classes at a glance: ISO 286 tolerance charts. The same chart in German: h6 Toleranz.