---
type: chart
title: "ISO 286 Fits & Tolerance Chart (Hole Basis)"
tables: 8
url: https://manufacturingprocesses.org/charts/iso-286-fits-tolerances
---

# ISO 286 Fits & Tolerance Chart (Hole Basis)

Preferred hole-basis fits, IT6–IT11 standard tolerance grades to 120 mm, and full deviation tables for H7/g6, H7/h6, H8/f7, H7/k6, H7/p6 and H7/s6.

In a **hole-basis** system the hole is the fixed member — always an H class,
lower deviation zero — and the shaft is varied to create the fit. This is
the default for general machining because reamers, broaches and plug gauges
come in fixed sizes while a shaft can be turned to any diameter. Shaft-basis
equivalents are listed alongside for the case where one ground shaft passes
through several different components.

The sign convention used throughout: **maximum clearance = hole upper
deviation − shaft lower deviation**, and **minimum clearance = hole lower
deviation − shaft upper deviation**. A negative result is interference.
All deviations are in micrometers.

As a rough process-capability guide: IT6 is precision grinding or honing,
IT7 is good reaming, fine turning or grinding, IT8 is normal turning, boring
and reaming, IT9 is general turning and milling, and IT10–IT11 covers
drilling, rough machining and cold drawing. H7 is the practical default for
a machined and reamed hole.

## Preferred hole-basis fits

| Fit (hole basis) | Shaft-basis equivalent | Category | Name | Typical use |
| --- | --- | --- | --- | --- |
| H11/c11 | C11/h11 | Clearance | Loose running | Wide clearance, accuracy irrelevant. Pivots, latches, parts exposed to heat, corrosion or contamination. |
| H9/d9 | D9/h9 | Clearance | Free running | Large clearance. High running speeds, big temperature swings, heavy journal pressure. |
| H8/f7 | F8/h7 | Clearance | Close running | Moderate accuracy. Plain bearings, spindles, sliding rods. |
| H7/g6 | G7/h6 | Clearance | Sliding | Minimal clearance with high accuracy; assembles easily and turns or slides freely. Guided shafts, sliding gears. |
| H7/h6 | H7/h6 | Clearance (zero-line) | Locational clearance | Very close clearance, no force to assemble, turns and slides when lubricated. Precise shaft location. |
| H7/k6 | K7/h6 | Transition | Locational transition (similar fit) | Negligible clearance or interference; mallet assembly. Hubs, gears, pulleys, bushes, bearings. |
| H7/n6 | N7/h6 | Transition | Locational transition (fixed fit) | Small interference, light press. Plugs, driven bushes, armatures on shafts. |
| H7/p6 | P7/h6 | Interference | Press fit | Light interference, cold press. Hubs, bearings, bushings, retainers. |
| H7/s6 | S7/h6 | Interference | Driving fit | Medium interference, hot press or heavy cold press. Permanent gear and shaft mounting. |
| H7/u6 | U7/h6 | Interference | Forced / shrink fit | High interference needing a large temperature differential. Permanent couplings that cannot be separated without damage. |

## IT grade standard tolerance values, IT6 – IT11, 0 – 120 mm

| Nominal size (mm) | IT6 (µm) | IT7 (µm) | IT8 (µm) | IT9 (µm) | IT10 (µm) | IT11 (µm) |
| --- | --- | --- | --- | --- | --- | --- |
| 0–3 | 6 | 10 | 14 | 25 | 40 | 60 |
| 3–6 | 8 | 12 | 18 | 30 | 48 | 75 |
| 6–10 | 9 | 15 | 22 | 36 | 58 | 90 |
| 10–18 | 11 | 18 | 27 | 43 | 70 | 110 |
| 18–30 | 13 | 21 | 33 | 52 | 84 | 130 |
| 30–50 | 16 | 25 | 39 | 62 | 100 | 160 |
| 50–80 | 19 | 30 | 46 | 74 | 120 | 190 |
| 80–120 | 22 | 35 | 54 | 87 | 140 | 220 |

## H7/g6 — Sliding / close clearance

| Nominal size (mm) | H7 hole (µm) | g6 shaft (µm) | Max clearance (µm) | Min clearance (µm) | Result |
| --- | --- | --- | --- | --- | --- |
| 0–3 | +10/+0 | -2/-8 | 18 | 2 | clearance |
| 3–6 | +12/+0 | -4/-12 | 24 | 4 | clearance |
| 6–10 | +15/+0 | -5/-14 | 29 | 5 | clearance |
| 10–18 | +18/+0 | -6/-17 | 35 | 6 | clearance |
| 18–30 | +21/+0 | -7/-20 | 41 | 7 | clearance |
| 30–50 | +25/+0 | -9/-25 | 50 | 9 | clearance |
| 50–80 | +30/+0 | -10/-29 | 59 | 10 | clearance |
| 80–120 | +35/+0 | -12/-34 | 69 | 12 | clearance |

## H7/h6 — Locational clearance

| Nominal size (mm) | H7 hole (µm) | h6 shaft (µm) | Max clearance (µm) | Min clearance (µm) | Result |
| --- | --- | --- | --- | --- | --- |
| 0–3 | +10/+0 | +0/-6 | 16 | 0 | clearance |
| 3–6 | +12/+0 | +0/-8 | 20 | 0 | clearance |
| 6–10 | +15/+0 | +0/-9 | 24 | 0 | clearance |
| 10–18 | +18/+0 | +0/-11 | 29 | 0 | clearance |
| 18–30 | +21/+0 | +0/-13 | 34 | 0 | clearance |
| 30–50 | +25/+0 | +0/-16 | 41 | 0 | clearance |
| 50–80 | +30/+0 | +0/-19 | 49 | 0 | clearance |
| 80–120 | +35/+0 | +0/-22 | 57 | 0 | clearance |

## H8/f7 — Close running

| Nominal size (mm) | H8 hole (µm) | f7 shaft (µm) | Max clearance (µm) | Min clearance (µm) | Result |
| --- | --- | --- | --- | --- | --- |
| 0–3 | +14/+0 | -6/-16 | 30 | 6 | clearance |
| 3–6 | +18/+0 | -10/-22 | 40 | 10 | clearance |
| 6–10 | +22/+0 | -13/-28 | 50 | 13 | clearance |
| 10–18 | +27/+0 | -16/-34 | 61 | 16 | clearance |
| 18–30 | +33/+0 | -20/-41 | 74 | 20 | clearance |
| 30–50 | +39/+0 | -25/-50 | 89 | 25 | clearance |
| 50–80 | +46/+0 | -30/-60 | 106 | 30 | clearance |
| 80–120 | +54/+0 | -36/-71 | 125 | 36 | clearance |

## H7/k6 — Locational transition

| Nominal size (mm) | H7 hole (µm) | k6 shaft (µm) | Max clearance (µm) | Min clearance (µm) | Result |
| --- | --- | --- | --- | --- | --- |
| 0–3 | +10/+0 | +6/+0 | 10 | -6 | transition |
| 3–6 | +12/+0 | +9/+1 | 11 | -9 | transition |
| 6–10 | +15/+0 | +10/+1 | 14 | -10 | transition |
| 10–18 | +18/+0 | +12/+1 | 17 | -12 | transition |
| 18–30 | +21/+0 | +15/+2 | 19 | -15 | transition |
| 30–50 | +25/+0 | +18/+2 | 23 | -18 | transition |
| 50–80 | +30/+0 | +21/+2 | 28 | -21 | transition |
| 80–120 | +35/+0 | +25/+3 | 32 | -25 | transition |

## H7/p6 — Press / locational interference

| Nominal size (mm) | H7 hole (µm) | p6 shaft (µm) | Max clearance (µm) | Min clearance (µm) | Result |
| --- | --- | --- | --- | --- | --- |
| 0–3 | +10/+0 | +12/+6 | 4 | -12 | transition |
| 3–6 | +12/+0 | +20/+12 | 0 | -20 | interference |
| 6–10 | +15/+0 | +24/+15 | 0 | -24 | interference |
| 10–18 | +18/+0 | +29/+18 | 0 | -29 | interference |
| 18–30 | +21/+0 | +35/+22 | -1 | -35 | interference |
| 30–50 | +25/+0 | +42/+26 | -1 | -42 | interference |
| 50–80 | +30/+0 | +51/+32 | -2 | -51 | interference |
| 80–120 | +35/+0 | +59/+37 | -2 | -59 | interference |

## H7/s6 — Driving / medium interference

| Nominal size (mm) | H7 hole (µm) | s6 shaft (µm) | Max clearance (µm) | Min clearance (µm) | Result |
| --- | --- | --- | --- | --- | --- |
| 0–3 | +10/+0 | +20/+14 | -4 | -20 | interference |
| 3–6 | +12/+0 | +27/+19 | -7 | -27 | interference |
| 6–10 | +15/+0 | +32/+23 | -8 | -32 | interference |
| 10–18 | +18/+0 | +39/+28 | -10 | -39 | interference |
| 18–30 | +21/+0 | +48/+35 | -14 | -48 | interference |
| 30–50 | +25/+0 | +59/+43 | -18 | -59 | interference |
| 50–65 | +30/+0 | +72/+53 | -23 | -72 | interference |
| 65–80 | +30/+0 | +78/+59 | -29 | -78 | interference |
| 80–100 | +35/+0 | +93/+71 | -36 | -93 | interference |
| 100–120 | +35/+0 | +101/+79 | -44 | -101 | interference |

## Notes

**A web-search summary returned IT6 = 0.8, IT7 = 1.2 and IT8 = 2 µm for the
0–3 mm range. Those are wrong** — they are the IT1/IT2/IT3 values, off by
five grade columns. The correct 0–3 mm values are IT6 = 6, IT7 = 10,
IT8 = 14 µm. This is worth flagging because it is exactly the kind of error
that propagates into AI-generated reference tables.

**The s6 table subdivides where the others do not.** ISO 286 splits 50–80 mm
into 50–65 and 65–80, and 80–120 mm into 80–100 and 100–120, for the s and u
shaft classes only. Those four bands are preserved here; every other table
collapsing them is correct behaviour, not an omission.

**Every deviation on this page was independently re-derived from ISO 286
first principles** (fundamental deviation plus IT grade width) and
cross-checked against a second source. Examples: g6 at 50–80 → deviation
−10 µm, IT6 = 19 → −10/−29. k6 at 80–120 → +3, IT6 = 22 → +25/+3. p6 at
50–80 → +32, IT6 = 19 → +51/+32. f7 at 80–120 → −36, IT7 = 35 → −36/−71.
The deviation table and the IT grade table came from different sources and
agree to the last micrometer.

**IT10 is single-source.** IT6, IT7, IT8, IT9 and IT11 were confirmed by two
independent sources; IT10 appears in only one, but sits correctly in the
geometric progression between the two-source-verified IT9 and IT11 rows.

## FAQ

### What is an H7 tolerance?

H7 is a hole with a lower deviation of zero and an upper deviation equal to the IT7 grade width for that size. At 10–18 mm that is +18/+0 µm; at 30–50 mm it is +25/+0 µm. It is the practical default for a machined and reamed hole.

### What is the difference between H7/g6 and H7/h6?

H7/h6 is a zero-line clearance fit: minimum clearance is exactly zero, so the parts assemble without force but are not intended to run. H7/g6 pulls the shaft down slightly to guarantee a small clearance — +2 to +18 µm at 0–3 mm — so the joint slides and turns freely when lubricated.

### Which fit should I use for a press fit?

H7/p6 for a light cold press — at 18–30 mm it gives −1 to −35 µm — and H7/s6 for medium interference needing heat or heavy press force, which at the same size gives −14 to −48 µm. H7/u6 is the forced or shrink fit for permanent couplings.

### What does hole basis mean?

The hole is held at a fixed tolerance class (always H, with zero lower deviation) and the fit is changed by varying the shaft. It is the default in general machining because reamers, broaches and plug gauges come in fixed sizes while shafts can be turned to any diameter.

### How do I calculate clearance from a fit?

Maximum clearance = hole upper deviation − shaft lower deviation; minimum clearance = hole lower deviation − shaft upper deviation. A negative answer is interference. For H8/f7 at Ø50, that gives +89 and +25 µm.

### Is H7/p6 always an interference fit?

No. In the 0–3 mm range H7/p6 is technically a transition fit: it runs from +4 µm clearance to −12 µm interference. From 3 mm upward it is interference throughout.

### What machining process holds an IT7 tolerance?

Good reaming, fine turning or grinding. IT6 needs precision grinding or honing, IT8 is achievable with normal turning, boring and reaming, and IT10–IT11 covers drilling, rough machining and cold-drawn stock.

## Sources

- [Engineers Edge — International Tolerance (IT) Grades Table Chart, ISO 286-1:2010](https://www.engineersedge.com/international_tol.htm)
- [Wikipedia — Engineering fit (cited to Engineers Black Book 2nd ed., p. 70)](https://en.wikipedia.org/wiki/Engineering_fit)

## Related processes

- [CNC Turning](https://manufacturingprocesses.org/processes/cutting/cnc-turning.md)
- [CNC Milling](https://manufacturingprocesses.org/processes/cutting/cnc-milling.md)
- [Electrical Discharge Machining](https://manufacturingprocesses.org/processes/cutting/electrical-discharge-machining.md)
- [Grinding, Sanding and Polishing](https://manufacturingprocesses.org/processes/finishing/grinding-sanding-and-polishing.md)

## Related charts

- [Surface Finish Chart](https://manufacturingprocesses.org/charts/surface-finish-chart.md)
- [Drill Size Chart](https://manufacturingprocesses.org/charts/drill-size-chart.md)

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*Source: [Manufacturing Processes](https://manufacturingprocesses.org/charts/iso-286-fits-tolerances)*

*Last updated: August 11, 2026*