ISO 286 tolerance classes
Every hole and shaft tolerance class in the calculator, with limits from 1 to 500 mm. Grade tables: IT grades · fundamental deviations.
Hole classes (capital letters)
| A | large clearance | |
| B | large clearance | |
| C | large clearance | |
| D | running clearance | |
| E | running clearance | |
| F | close running | |
| G | sliding | |
| H | zero line | |
| JS | symmetric ±IT/2 | |
| K | transition | |
| M | tight transition | |
| N | tight transition | |
| P | press | |
| R | press | |
| S | heavy interference | |
| T | heavy interference | |
| U | heavy interference | |
| X | heavy interference |
Shaft classes (lower case)
| a | large clearance | |
| b | large clearance | |
| c | large clearance | |
| d | running clearance | |
| e | running clearance | |
| f | close running | |
| g | sliding | |
| h | zero line | |
| js | symmetric ±IT/2 | |
| j | transition | |
| k | transition | |
| m | tight transition | |
| n | tight transition | |
| p | press | |
| r | press | |
| s | heavy interference | |
| t | heavy interference | |
| u | heavy interference | |
| x | heavy interference | |
| z | heavy interference |
How to read a class
A class like H7 or g6 has two parts: a letter for the fundamental deviation (where the tolerance zone sits relative to the nominal size — H/h sit right on it) and a number for the IT grade (how wide the zone is — smaller numbers are tighter). Capital letters are hole classes, lower case are shaft classes; pairing an H hole with a lower-case shaft (or an h shaft with a capital hole) gives a standard ISO 286 fit — see each class's page for its full size table and the fits it's used in. For a worked example, see how to read H7/g6.