Fits & limits (ISO 286)
For a 25 mm shaft in an H7/g6 sliding fit, the hole runs +0 / +21 µm and the shaft −7 / −20 µm, giving 7–41 µm of clearance. This page computes ISO 286 limit deviations for any nominal size and hole/shaft tolerance class, and tells you whether the pair is a clearance, transition, or interference fit.
Enter a nominal diameter and designations like H7 and g6, or click a preferred fit to load it. Deviations are shown in µm and as absolute limits in mm.
- Hole H7
- —
- Shaft g6
- —
- Resulting fit
- —
Across size ranges
| Nominal (mm) | Hole H7 (µm) | Shaft g6 (µm) |
|---|
Preferred fits
| Fit | Type | Application |
|---|---|---|
| clearance | Loose running fit — wide commercial tolerances | |
| clearance | Free running fit — large temperature variations, high running speeds | |
| clearance | Close running fit — accurate machinery, moderate speeds and pressures | |
| clearance | Sliding fit — accurate location, free to move and turn | |
| clearance | Locational clearance — snug fit, freely assembled and disassembled | |
| transition | Locational transition — accurate location, compromise between clearance and interference | |
| transition | Locational transition — more accurate location, slight interference possible | |
| transition | Locational transition — more accurate location, greater interference likely | |
| interference | Locational interference — rigidity and alignment, no special bore pressure needed | |
| interference | Light press fit — light assembly pressure, semi-permanent assembly | |
| interference | Medium drive fit — steel parts, light shrink fits on cast iron |
What do H7 and g6 mean?
An ISO 286 tolerance class combines a fundamental deviation (a letter — its position relative to the nominal size) with a tolerance grade (a number, IT01–IT18 — the width of the tolerance zone). Upper-case letters (H, G, F) are holes; lower-case (h, g, f) are shafts.
So H7 is a hole whose lower limit sits exactly on the nominal size with an IT7-wide zone above it, and g6 is a shaft sitting just below nominal with an IT6-wide zone. The grade width scales with nominal size, which is why the deviations change across the size-range table above.
How is the type of fit determined?
Clearance is hole − shaft. The minimum clearance is the hole’s lower limit minus the shaft’s upper limit; the maximum clearance is the hole’s upper limit minus the shaft’s lower limit. If both are positive the pair always has clearance; if both are negative it is always interference; if the range straddles zero it is a transition fit.