Tolerance chart
H6 tolerance (hole): ISO 286 chart up to 500 mm
H6 is an ISO tolerance class for holes (internal features) under ISO 286. At Ø25 mm it means +13 / 0 µm: the size may lie between 25.000 and 25.013 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 | +6 | 0 | 6 |
| 3 – 6 | +8 | 0 | 8 |
| 6 – 10 | +9 | 0 | 9 |
| 10 – 18 | +11 | 0 | 11 |
| 18 – 30 | +13 | 0 | 13 |
| 30 – 50 | +16 | 0 | 16 |
| 50 – 80 | +19 | 0 | 19 |
| 80 – 120 | +22 | 0 | 22 |
| 120 – 180 | +25 | 0 | 25 |
| 180 – 250 | +29 | 0 | 29 |
| 250 – 315 | +32 | 0 | 32 |
| 315 – 400 | +36 | 0 | 36 |
| 400 – 500 | +40 | 0 | 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 upwards: the hole is never smaller 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 25.000 and 25.013 mm.
Fits with H6 at Ø25 mm
Hole-basis system: the hole stays H6, the shaft changes. Clearance in µm; a minus means interference. Sorted from the largest minimum clearance to the largest interference.
| Fit | Type | Max. clearance | Min. clearance |
|---|---|---|---|
| H6/f6 | clearance fit | 46 | 20 |
| H6/g5 | clearance fit | 29 | 7 |
| H6/g6 | clearance fit | 33 | 7 |
| H6/h5 | clearance fit | 22 | 0 |
| H6/h6 | clearance fit | 26 | 0 |
| H6/js5 | transition fit | 17.5 | −4.5 |
| H6/js6 | transition fit | 19.5 | −6.5 |
| H6/k5 | transition fit | 11 | −11 |
| H6/k6 | transition fit | 11 | −15 |
| H6/m5 | transition fit | 5 | −17 |
| H6/m6 | transition fit | 5 | −21 |
| H6/n5 | interference fit | −2 | −24 |
| H6/n6 | interference fit | −2 | −28 |
| H6/p6 | interference fit | −9 | −35 |
| H6/r6 | interference fit | −15 | −41 |
| H6/s6 | interference fit | −22 | −48 |
Frequently asked questions about H6
What does H6 mean?
H6 is an ISO tolerance class for holes (internal features): the letter H sets the position of the tolerance zone, the number 6 the standard tolerance grade IT6. At Ø25 mm that gives +13 / 0 µm, i.e. 25.000 to 25.013 mm.
What are the H6 limits at Ø10 and Ø50 mm?
Ø10 H6: +9 / 0 µm (10.000 to 10.009 mm). Ø50 H6: +16 / 0 µm (50.000 to 50.016 mm).
Is H6 a clearance fit?
A tolerance class on its own is not a fit – only together with its mating part. H6/g5 at Ø25 mm is a clearance fit (maximum clearance 29 µm, minimum clearance 7 µm; a minus means interference).
More tolerance classes
Same letter H, other grades: H7 · H8 · H9 · H10 · H11
Holes in grade 6: G6 · JS6 · K6 · M6 · N6 · P6
All classes at a glance: ISO 286 tolerance charts. The same chart in German: H6 Toleranz.