Calculate limit deviations, tolerance width, and minimum and maximum size for one ISO 286 hole or shaft tolerance class.
Evaluate one toleranced size such as 20 H7 or 16 h6.
Enter nominal size, feature type (hole or shaft), position letter and IT grade. Uppercase letters identify holes, lowercase letters shafts; IT01 to IT18 defines tolerance width.
Nominal size and IT grade are coupled: the same IT number is generally wider at a larger size. The position letter shifts the zone, so H7 for a hole is not the same as h7 for a shaft.
The tabulated deviations are added to nominal size to obtain lower and upper deviation and the minimum and maximum size.
20 H7 means the lower hole deviation is zero; the upper deviation is the IT7 width for the nominal-size step over 18 to 30 mm.
Sources and limits: ISO 286-1 and ISO 286-2 at the 20 °C reference temperature; verified for nominal sizes above 0 up to 500 mm.
Evaluate one toleranced size such as 20 H7 or 16 h6.
A tolerance defines the permitted size range of a manufactured feature. Its position locates that range around the zero line, while the IT grade sets its width.
The tabulated deviations are added to nominal size to obtain lower and upper deviation and the minimum and maximum size.
Enter nominal size, feature type (hole or shaft), position letter and IT grade. Uppercase letters identify holes, lowercase letters shafts; IT01 to IT18 defines tolerance width. Nominal size and IT grade are coupled: the same IT number is generally wider at a larger size. The position letter shifts the zone, so H7 for a hole is not the same as h7 for a shaft.
Enter nominal size, feature type (hole or shaft), position letter and IT grade, or enter a designation such as 20 H7 directly. The calculator returns upper and lower deviation and minimum/maximum size.
20 H7 means the lower hole deviation is zero; the upper deviation is the IT7 width for the nominal-size step over 18 to 30 mm.
Nominal size and IT grade are coupled: the same IT number is generally wider at a larger size. The position letter shifts the zone, so H7 for a hole is not the same as h7 for a shaft. Positive clearance means the hole remains larger than the shaft in the least favorable limits. A negative result is interference and needs separate assembly, temperature and joining checks.
Nominal size in millimetres, deviations in micrometres or millimetres depending on display.
Looking up limit sizes for a single dimension on drawings, inspection reports or manufacturing instructions, without calculating a complete fit.
ISO 286-1 and ISO 286-2 at the 20 °C reference temperature; verified for nominal sizes above 0 up to 500 mm.
Common mistake: Don't assume the same IT grade gives the same absolute tolerance width at a different nominal size – IT grades are tied to the nominal-size step and widen as size increases. A single tolerance field describes only one part; clearance or interference needs the mating part as well.
IT7 is one of 20 standardized tolerance grades (IT01 to IT18); the actual width in micrometres also depends on the nominal-size step and is tabulated in ISO 286-1.
H is defined as the hole field with zero fundamental deviation at the lower limit; the entire tolerance width therefore lies above nominal size.
No, this tool evaluates only a single tolerance field. For clearance or interference between two parts, use the fits calculator with hole and shaft fields together.
From nominal size and one tolerance class, it returns lower/upper deviations, tolerance width, and limit sizes.
The single-size calculator helps interpret and define a tolerance zone. It deliberately does not decide which mating part provides the required function.
Uppercase letters identify internal sizes; lowercase letters identify external sizes.
A two-point diameter does not fully describe form deviation.
Combine both tolerance zones whenever clearance or interference matters.
Defines unambiguous specification and interpretation of linear sizes.
Fundamental GPS rules and independence of requirements.
Adds the geometrical tolerances required beyond size.