Question 1

What does a fit designation like H7/g6 mean?

Accepted Answer

H7/g6 describes a shaft-hole fit. The capital letter and number (H7) are the hole's fundamental deviation and IT tolerance grade; the lowercase letter and number (g6) are the shaft's. H means the hole's lower deviation is zero. The calculator returns the exact upper and lower deviations and the resulting clearance or interference.

Question 2

What is the difference between clearance, transition and interference fits?

Accepted Answer

A clearance fit always leaves a gap (minimum clearance ≥ 0). An interference fit always overlaps (maximum clearance ≤ 0), requiring force or heat to assemble. A transition fit can be either depending on the actual sizes within tolerance. The tool classifies the fit automatically from the computed limits.

Question 3

What range does the ISO 286 calculator support?

Accepted Answer

Nominal diameters from over 3 mm up to 500 mm, hole H, shaft letters g, h, js, k, m, n, p and s, and IT grades 5 through 9, all based on ISO 286-1:2010. For letters, ranges or grades outside this set, refer directly to the standard.

ISO 286 Fits and Tolerances

How to read an ISO 286 designation