Iso Tolerance Standards Jun 2026

The number represents the "International Tolerance" (IT) grade. It defines the size of the tolerance band. The smaller the number, the tighter (more precise) the tolerance.

The hole and shaft are nearly the same size. Depending on the actual manufactured dimensions, the shaft might be slightly smaller (clearance) or slightly larger (interference) than the hole. This provides accurate location but allows for assembly/disassembly. iso tolerance standards

Before diving into the ISO system, it is essential to understand the concept of tolerance. The hole and shaft are nearly the same size

Interesting rule of thumb: moving from costs ~2–3x more; IT5 to IT4 costs another ~2–3x. That’s the “tolerance-price cliff.” Before diving into the ISO system, it is

Note: The magnitude of the tolerance increases with the size of the part. An IT7 tolerance on a 5mm part is physically smaller than an IT7 tolerance on a 500mm part.