ISO 286 · clearance fit · IT6
h6 shaft tolerance
The h6 limits we cut to at every common nominal, computed from the ISO 286 fundamental deviation for h and the IT6 grade. Same numbers the configurator stamps on a h6 diameter.
h6 is a clearance class with its upper limit exactly at nominal: the shaft is never oversize, so a nominal-size bore always slides on. The letter h fixes where the band sits relative to nominal (the fundamental deviation); the grade 6 fixes how wide it is (IT6). Both come from the ISO 286 tables and scale with diameter, which is why one page per class, with every nominal, is more useful than a single number.
At a 1″ nominal the h6 band is +.0000 to -.0005: the shaft measures between 0.9995″ and 1″, a 0.0005″ window. The table gives the same limits at the inch and metric nominals we turn most.
Pick h6 on any diameter in the configurator and the drawing carries exactly these limits; the engine computes them from the standard for the diameter you enter, not from this table.
h6 limits by nominal diameter
| Nominal Ø | Upper dev. | Lower dev. | Max Ø (in) | Min Ø (in) | Band (in) |
|---|---|---|---|---|---|
| 1/4″ (0.25) | +.0000 | -.0004 | 0.25 | 0.2496 | 0.0004 |
| 3/8″ (0.375) | +.0000 | -.0004 | 0.375 | 0.3746 | 0.0004 |
| 1/2″ (0.5) | +.0000 | -.0004 | 0.5 | 0.4996 | 0.0004 |
| 5/8″ (0.625) | +.0000 | -.0004 | 0.625 | 0.6246 | 0.0004 |
| 3/4″ (0.75) | +.0000 | -.0005 | 0.75 | 0.7495 | 0.0005 |
| 7/8″ (0.875) | +.0000 | -.0005 | 0.875 | 0.8745 | 0.0005 |
| 1″ (1) | +.0000 | -.0005 | 1 | 0.9995 | 0.0005 |
| 1-1/8″ (1.125) | +.0000 | -.0005 | 1.125 | 1.1245 | 0.0005 |
| 1-1/4″ (1.25) | +.0000 | -.0006 | 1.25 | 1.2494 | 0.0006 |
| 1-3/8″ (1.375) | +.0000 | -.0006 | 1.375 | 1.3744 | 0.0006 |
| 1-1/2″ (1.5) | +.0000 | -.0006 | 1.5 | 1.4994 | 0.0006 |
| 1-3/4″ (1.75) | +.0000 | -.0006 | 1.75 | 1.7494 | 0.0006 |
| 2″ (2) | +.0000 | -.0007 | 2 | 1.9993 | 0.0007 |
| 2-1/2″ (2.5) | +.0000 | -.0007 | 2.5 | 2.4993 | 0.0007 |
| 3″ (3) | +.0000 | -.0007 | 3 | 2.9993 | 0.0007 |
| 4″ (4) | +.0000 | -.0009 | 4 | 3.9991 | 0.0009 |
| Metric nominals (limits in inches) | |||||
| 20 mm (0.7874″) | +.0000 | -.0005 | 0.7874 | 0.7869 | 0.0005 |
| 25 mm (0.9843″) | +.0000 | -.0005 | 0.9843 | 0.9837 | 0.0005 |
| 30 mm (1.1811″) | +.0000 | -.0005 | 1.1811 | 1.1806 | 0.0005 |
| 35 mm (1.378″) | +.0000 | -.0006 | 1.378 | 1.3773 | 0.0006 |
| 40 mm (1.5748″) | +.0000 | -.0006 | 1.5748 | 1.5742 | 0.0006 |
| 45 mm (1.7717″) | +.0000 | -.0006 | 1.7717 | 1.771 | 0.0006 |
| 50 mm (1.9685″) | +.0000 | -.0006 | 1.9685 | 1.9679 | 0.0006 |
| 55 mm (2.1654″) | +.0000 | -.0007 | 2.1654 | 2.1646 | 0.0007 |
| 60 mm (2.3622″) | +.0000 | -.0007 | 2.3622 | 2.3615 | 0.0007 |
| 65 mm (2.5591″) | +.0000 | -.0007 | 2.5591 | 2.5583 | 0.0007 |
Deviations from nominal in inches at 0.0001 in resolution; max and min are the finished diameter limits. Metric nominals are converted and the limits shown in inches.
Applications and finish targets for h6
| Application | Finish target (Ra, µin) |
|---|---|
| Bearing seat (inner ring on a rotating shaft) | 32 |
| Locating diameter | 16 |
Part of Shaft fits and tolerances. Other pages in the series: d9 · e8 · f7 · g6 · h7 · h8 · js6 · j6 · k5 · k6 · m6 · n6 · p6 · r6 · s6 · 1/4″ · 3/8″ · 1/2″ · 5/8″ · 3/4″ · 7/8″ · 1″ · 1-1/8″ · 1-1/4″ · 1-3/8″ · 1-1/2″ · 1-3/4″ · 2″ · 2-1/2″ · 3″ · 4″ · 20 mm · 25 mm · 30 mm · 35 mm · 40 mm · 45 mm · 50 mm · 55 mm · 60 mm · 65 mm.
Where h6 is used
These are the applications the configurator associates with h6, with the surface-finish target it applies to that diameter. A fit class sets size; the finish is what makes the size hold in service.
Clearance fit, by the numbers
Every h6 limit is at or below nominal, so against a nominal (H-basis) bore the minimum gap is 0″ and the maximum is set by the bore's own tolerance plus 0.0005″ at 1″. Tighter grades narrow the shaft's share of that range.
Frequently Asked Questions
These references are for specifying a part; every value here is one the configurator applies when you build one. Numbers are representative of the standard; check them against your part and its mating components before ordering. See all guides on the guides page.