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MFG Processes

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.

Tables
8
Rows
68
Units
mm, µm
References
2
Revised
2026-08-11

Preferred hole-basis fits

10 rows
Fit (hole basis)Shaft-basis equivalentCategoryNameTypical use
H11/c11C11/h11ClearanceLoose runningWide clearance, accuracy irrelevant. Pivots, latches, parts exposed to heat, corrosion or contamination.
H9/d9D9/h9ClearanceFree runningLarge clearance. High running speeds, big temperature swings, heavy journal pressure.
H8/f7F8/h7ClearanceClose runningModerate accuracy. Plain bearings, spindles, sliding rods.
H7/g6G7/h6ClearanceSlidingMinimal clearance with high accuracy; assembles easily and turns or slides freely. Guided shafts, sliding gears.
H7/h6H7/h6Clearance (zero-line)Locational clearanceVery close clearance, no force to assemble, turns and slides when lubricated. Precise shaft location.
H7/k6K7/h6TransitionLocational transition (similar fit)Negligible clearance or interference; mallet assembly. Hubs, gears, pulleys, bushes, bearings.
H7/n6N7/h6TransitionLocational transition (fixed fit)Small interference, light press. Plugs, driven bushes, armatures on shafts.
H7/p6P7/h6InterferencePress fitLight interference, cold press. Hubs, bearings, bushings, retainers.
H7/s6S7/h6InterferenceDriving fitMedium interference, hot press or heavy cold press. Permanent gear and shaft mounting.
H7/u6U7/h6InterferenceForced / shrink fitHigh interference needing a large temperature differential. Permanent couplings that cannot be separated without damage.

10 rows × 5 columns

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

8 rows
Nominal sizemmIT6µmIT7µmIT8µmIT9µmIT10µmIT11µm
0–361014254060
3–681218304875
6–1091522365890
10–181118274370110
18–301321335284130
30–5016253962100160
50–8019304674120190
80–12022355487140220

8 rows × 7 columnsUnits: mm, µm

Basis and references

Read before use

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.

References

  1. [1]Engineers Edge — International Tolerance (IT) Grades Table Chart, ISO 286-1:2010
  2. [2]Wikipedia — Engineering fit (cited to Engineers Black Book 2nd ed., p. 70)

Every value on this page was set against at least two of these sources and recomputed rather than transcribed. Where they disagree, the disagreement is recorded in the notes below.

H7/g6 — Sliding / close clearance

8 rows
Nominal sizemmH7 holeµmg6 shaftµmMax clearanceµmMin clearanceµmResult
0–3+10/+0-2/-8182clearance
3–6+12/+0-4/-12244clearance
6–10+15/+0-5/-14295clearance
10–18+18/+0-6/-17356clearance
18–30+21/+0-7/-20417clearance
30–50+25/+0-9/-25509clearance
50–80+30/+0-10/-295910clearance
80–120+35/+0-12/-346912clearance

8 rows × 6 columnsUnits: mm, µm

H7/h6 — Locational clearance

8 rows
Nominal sizemmH7 holeµmh6 shaftµmMax clearanceµmMin clearanceµmResult
0–3+10/+0+0/-6160clearance
3–6+12/+0+0/-8200clearance
6–10+15/+0+0/-9240clearance
10–18+18/+0+0/-11290clearance
18–30+21/+0+0/-13340clearance
30–50+25/+0+0/-16410clearance
50–80+30/+0+0/-19490clearance
80–120+35/+0+0/-22570clearance

8 rows × 6 columnsUnits: mm, µm

H8/f7 — Close running

8 rows
Nominal sizemmH8 holeµmf7 shaftµmMax clearanceµmMin clearanceµmResult
0–3+14/+0-6/-16306clearance
3–6+18/+0-10/-224010clearance
6–10+22/+0-13/-285013clearance
10–18+27/+0-16/-346116clearance
18–30+33/+0-20/-417420clearance
30–50+39/+0-25/-508925clearance
50–80+46/+0-30/-6010630clearance
80–120+54/+0-36/-7112536clearance

8 rows × 6 columnsUnits: mm, µm

H7/k6 — Locational transition

8 rows
Nominal sizemmH7 holeµmk6 shaftµmMax clearanceµmMin clearanceµmResult
0–3+10/+0+6/+010-6transition
3–6+12/+0+9/+111-9transition
6–10+15/+0+10/+114-10transition
10–18+18/+0+12/+117-12transition
18–30+21/+0+15/+219-15transition
30–50+25/+0+18/+223-18transition
50–80+30/+0+21/+228-21transition
80–120+35/+0+25/+332-25transition

8 rows × 6 columnsUnits: mm, µm

H7/p6 — Press / locational interference

8 rows
Nominal sizemmH7 holeµmp6 shaftµmMax clearanceµmMin clearanceµmResult
0–3+10/+0+12/+64-12transition
3–6+12/+0+20/+120-20interference
6–10+15/+0+24/+150-24interference
10–18+18/+0+29/+180-29interference
18–30+21/+0+35/+22-1-35interference
30–50+25/+0+42/+26-1-42interference
50–80+30/+0+51/+32-2-51interference
80–120+35/+0+59/+37-2-59interference

8 rows × 6 columnsUnits: mm, µm

H7/s6 — Driving / medium interference

10 rows
Nominal sizemmH7 holeµms6 shaftµmMax clearanceµmMin clearanceµmResult
0–3+10/+0+20/+14-4-20interference
3–6+12/+0+27/+19-7-27interference
6–10+15/+0+32/+23-8-32interference
10–18+18/+0+39/+28-10-39interference
18–30+21/+0+48/+35-14-48interference
30–50+25/+0+59/+43-18-59interference
50–65+30/+0+72/+53-23-72interference
65–80+30/+0+78/+59-29-78interference
80–100+35/+0+93/+71-36-93interference
100–120+35/+0+101/+79-44-101interference

10 rows × 6 columnsUnits: mm, µm

Revision and twin

2026-08-11

Last reviewed . This page carries 68 rows across 8 tables, all of them in the HTML — nothing is paginated, gated or fetched.

Plain-Markdown twin: /charts/iso-286-fits-tolerances.md

Notes to the tables

4 notes

Where this data disagrees with itself, with other published charts, or with what the number looks like it means.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

Questions

7 questions
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.

How to cite this page

Manufacturing Processes. “ISO 286 Fits & Tolerance Chart (Hole Basis).” manufacturingprocesses.org, last reviewed 2026-08-11. https://manufacturingprocesses.org/charts/iso-286-fits-tolerances

If you reproduce a table, cite the standard it derives from as well — the references are the primary sources, this page is a cross-checked transcription of them.