I Open-Sourced the ISO 286 Fit Tables Behind My Tolerance Tool

Description and use

The repo offers computed ISO 286-2 fit tables for common design combinations, enabling automated tolerance analysis.

Problem

PDF tables for ISO 286-2 were inconvenient to use in code.

Outcome

The repository provides a lightweight, code-friendly source of ISO 286-2 fit tables for common design subsets, reducing reliance on PDF tables and enabling automated tolerance analysis.

Workflow

• 1. Clone the repo from https://github.com/chenzefeng09/iso-286-fits.
• 2. Run the Python script: python iso286.py 25 H7/p6 to get fit limits for a 25 mm hole with H7/p6 fit.
• 3. Use the TypeScript module or import fits.json for integration into other projects.
• 4. For non-code use, visit https://nxtolerance.com/standards to view the calculator in a browser.

Evidence

Tired of PDF tables, I keep a computed subset of ISO 286-2 in code — limits & fits for the hole-basis combinations that actually show up on drawings: IT5–IT8, shafts f/g/h/k/p, all 13 size bands to 500 mm.

Source

Now it's a standalone MIT repo. Three ways to use it: python iso286.py 25 H7/p6 ...

Source

Honest scope note: this is the common-design subset — shafts outside f/g/h/k/p, grades outside IT5–IT8, and shaft-basis fits aren't in it.

Source