ISO Fits & Tolerances
Limits for a hole, a shaft, or both, and the fit they make together.
Hole
—Shaft
—Method & sources
Calculated to ISO 286 for basic sizes from 3 to 400 mm. Sources: the published ISO 286 tables and the open isofits data set.
Zones s, t and u are not included. JS and js are ±IT/2. K above grade 8 is defined only up to 3 mm. CD, EF and FG (cd, ef, fg) are tabulated by ISO 286 up to 10 mm; above that they are calculated as ISO 286-1 allows.
Fit type is determined from the worst-case hole-minus-shaft range: always positive = clearance fit, always negative = interference fit, and a range that crosses zero = transition fit. Common fits are the ISO 286-1 / ANSI B4.2 preferred hole-basis fits this tool covers. ISO standards remain the authoritative engineering specification.