Type a size and a class or fit — H7, g6, H7/g6, H7/p6 — and get limit dimensions, deviations and fit character per ISO 286-1:2010. Plus ISO 2768 general tolerance tables.
For turned brass rod and CNC parts. Use the ISO 286 fits table to pick shaft/hole pairs for assemblies, the IT-grade table for the actual tolerance band at a given size, and ISO 2768 for untoleranced dimensions on the drawing.
Type a nominal size and a tolerance class — e.g. 8 + H6 — or a complete fit like H7/g6 to get limit sizes and the fit character. Computed per ISO 286-1:2010 / ISO 286-2:2010 (the current editions, confirmed June 2026).
Covers Ø0–500 mm, grades IT1–IT16, deviation letters D–P / d–p incl. H, h, JS, js (uppercase = hole, lowercase = shaft). Press-fit classes r, s and beyond — ask our engineers.
| Fit | Type | Character | Typical use on turned brass parts |
|---|---|---|---|
| H7/g6 | Clearance | Close running / sliding | Spindles, guided pins, rotating shafts needing fine fit |
| H7/h6 | Clearance | Location / slide | Slip-fit locating spigots, parts assembled by hand |
| H8/f7 | Clearance | Free running | Bushings, bearings with lubrication, looser running fits |
| H11/c11 | Clearance | Loose | Wide clearance, weldments, non-critical assemblies |
| H7/k6 | Transition | Light keying | Located parts needing accuracy but occasional disassembly |
| H7/n6 | Transition | Tight | Press-located parts, light-duty drive without slip |
| H7/p6 | Interference | Press / drive | Inserts, bushes & pins retained by interference |
| H7/s6 | Interference | Heavy drive | Permanent press fits, shrink/force assembly |
Tolerance band width for a given nominal size. A hole H7 = 0 to +IT7; a shaft h6 = 0 to −IT6. Apply the fundamental deviation for other letters.
| Nominal size (mm) | IT6 | IT7 | IT8 | IT9 | IT11 |
|---|---|---|---|---|---|
| over 3 to 6 | 8 | 12 | 18 | 30 | 75 |
| over 6 to 10 | 9 | 15 | 22 | 36 | 90 |
| over 10 to 18 | 11 | 18 | 27 | 43 | 110 |
| over 18 to 30 | 13 | 21 | 33 | 52 | 130 |
| over 30 to 50 | 16 | 25 | 39 | 62 | 160 |
| over 50 to 80 | 19 | 30 | 46 | 74 | 190 |
| over 80 to 120 | 22 | 35 | 54 | 87 | 220 |
Worked example: a Ø20 mm H7 bore = 20.000 / 20.021 mm (0 to +21 µm). A Ø20 mm g6 shaft = 19.993 / 19.980 mm (−7 to −20 µm), giving a close-running clearance fit.
Applies to dimensions without an individual tolerance. We work to class medium (m) by default; tighter classes available on request.
| Nominal length (mm) | Fine (f) | Medium (m) | Coarse (c) | Very coarse (v) |
|---|---|---|---|---|
| 0.5 to 3 | ±0.05 | ±0.1 | ±0.2 | — |
| over 3 to 6 | ±0.05 | ±0.1 | ±0.3 | ±0.5 |
| over 6 to 30 | ±0.1 | ±0.2 | ±0.5 | ±1.0 |
| over 30 to 120 | ±0.15 | ±0.3 | ±0.8 | ±1.5 |
| over 120 to 400 | ±0.2 | ±0.5 | ±1.2 | ±2.5 |
| over 400 to 1000 | ±0.3 | ±0.8 | ±2.0 | ±4.0 |
Typical turned-brass capability: we routinely hold IT7–IT8 on diameters and ISO 2768-m or finer on lengths; critical features can be held to IT6 / ±0.01 mm with in-process gauging. State the fit or tolerance on your drawing and we quote to it.
References: ISO 286-1:2010 & ISO 286-2:2010 (GPS — code system for tolerances on linear sizes; current editions), ISO 1829 (selection of tolerance zones), ISO 2768-1 (general tolerances — linear & angular), ISO 2768-2 (geometrical). Values cross-checked against Machinery's Handbook. See our tolerances guide.
Capital letter+grade = the hole (H7), lowercase = the shaft (g6). The letter sets the position of the tolerance zone (fundamental deviation), the number its width (IT grade). H is the hole-basis reference: lower limit exactly at nominal. So Ø20 H7/g6 → hole 20.000–20.021, shaft 19.980–19.993: always a small clearance.
Running/sliding → H7/g6 or H8/f7; hand-assembled location → H7/h6; keyed or press-located → H7/k6 or H7/n6; permanent press fits (bushings, pins, inserts) → H7/p6 and beyond. Remember the press-fit side effect: pressing a bushing in closes its bore by ~70–90% of the interference — specify the bore for the installed state.
Toleranced features drive cost. Our routine capability on turned brass is IT7–IT8 on diameters and ISO 2768-m generally, with IT6 / ±0.005 mm held on critical features under in-process gauging — verified on CMM and optical measurement. Put tight classes only where the function demands them; the calculator above shows exactly what each class buys you.
Last reviewed: June 2026. Calculator outputs are estimates; verify against the governing standard and your drawing for procurement-critical work.
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