Computes the actual hole and shaft size limits (in mm) for the five most common ISO 286 hole-basis fits, given a nominal diameter. Also reports the resulting maximum/minimum clearance (or interference, if negative).
Inputs
Hole & Shaft Limits
Resulting Fit
A positive value is clearance (a gap between the parts); a negative value is interference (the shaft is actually larger than the hole, requiring a press or shrink fit to assemble).
How It Works
ISO 286 defines a tolerance grade (IT number, which sets the total tolerance width) and a fundamental deviation (a letter, which sets where that tolerance band sits relative to the nominal size) for both the hole and the shaft. In the hole-basis system used here, the hole is always grade H (lower deviation = 0, so the hole only grows larger than nominal), and the fit is controlled entirely by which shaft tolerance class is paired with it. This calculator looks up the standard IT grade and fundamental deviation values for your size range and computes the four resulting limit dimensions directly.
FAQ
Which fit should I use? H7/g6 or H7/f7 for parts that need to rotate or slide freely (bearings, bushings, sliding pins); H7/h6 for parts that locate accurately but do not need to move (dowel-located fixtures); H7/k6 for a light interference that still allows assembly by hand or mallet; H7/p6 for a true press fit that requires a press or heat to assemble (e.g. permanently installed bearing races).
Are these values exact to the standard? Yes, for the size ranges and fits listed — values come from the standard ISO 286-2 fundamental deviation and IT grade tables. For grades, letters, or sizes not covered here, consult the full ISO 286-2 standard.