Tolerance chart
n6 tolerance (shaft): ISO 286 chart up to 500 mm
n6 is an ISO tolerance class for shafts (external features) under ISO 286. At Ø25 mm it means +28 / +15 µm: the size may lie between 25.015 and 25.028 mm. Below are the deviations for every nominal size up to 500 mm and the fits that use n6.
n6 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 | +10 | +4 | 6 |
| 3 – 6 | +16 | +8 | 8 |
| 6 – 10 | +19 | +10 | 9 |
| 10 – 18 | +23 | +12 | 11 |
| 18 – 30 | +28 | +15 | 13 |
| 30 – 50 | +33 | +17 | 16 |
| 50 – 80 | +39 | +20 | 19 |
| 80 – 120 | +45 | +23 | 22 |
| 120 – 180 | +52 | +27 | 25 |
| 180 – 250 | +60 | +31 | 29 |
| 250 – 315 | +66 | +34 | 32 |
| 315 – 400 | +73 | +37 | 36 |
| 400 – 500 | +80 | +40 | 40 |
n6 for your nominal size
How n6 is built
An ISO tolerance class is a letter and a number. Capital letters stand for holes, small letters for shafts. The letter n sets the position of the tolerance zone; at Ø25 mm it lies entirely above the nominal size: the shaft is always 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 n6«; the inspection plan turns that into the limits 25.015 and 25.028 mm.
Fits with n6 at Ø25 mm
Hole-basis system: the hole is H, the shaft n6. Clearance in µm; a minus means interference. Sorted from the largest minimum clearance to the largest interference.
Frequently asked questions about n6
What does n6 mean?
n6 is an ISO tolerance class for shafts (external features): the letter n sets the position of the tolerance zone, the number 6 the standard tolerance grade IT6. At Ø25 mm that gives +28 / +15 µm, i.e. 25.015 to 25.028 mm.
What are the n6 limits at Ø10 and Ø50 mm?
Ø10 n6: +19 / +10 µm (10.010 to 10.019 mm). Ø50 n6: +33 / +17 µm (50.017 to 50.033 mm).
Is n6 a clearance fit?
A tolerance class on its own is not a fit – only together with its mating part. H7/n6 at Ø25 mm is a transition fit (maximum clearance 6 µm, minimum clearance −28 µm; a minus means interference).
More tolerance classes
Same letter n, other grades: n5
Shafts in grade 6: h6 · g6 · f6 · js6 · k6 · m6 · p6 · r6 · s6
All classes at a glance: ISO 286 tolerance charts. The same chart in German: n6 Toleranz.