ISO Tolerance/Fit Resources

I frequently have to generate ISO tolerance zone/fit callouts in my work. I struggled with this for a while, but have (mostly) gotten my head wrapped around the system, and wanted to share some of the resources I’ve found useful for designing these fits:

  • Theoretical Machinist ISO Tolerance Zone Calculator: AWESOME tool, gives you a visual display of the tolerance bands of the hole and shaft fits that you’ve specified, showing how much clearance/interference you’re designing in. Doesn’t have every possible fit, but all preferred fits and some less-common ones. This is what I use most of the time when I’m generating tolerance zone/fit callouts.
  • MDMetrics Fits and Tolerances PDF: Lots of information on preferred fits (first, second and third choice), with some info on International Tolerance grades and angle tolerancing. Tables of fit ranges are kinda useless once you’ve got the calculator linked to above, but the other info is worthwhile.
  • Misumi Tolerancing Cheatsheet: Gives real-world examples of different fit types.
(Note: I’m not affiliated with any of these groups, and have no responsibility for/ownership over the content of these pages – I just think they’re useful!)