I found myself needing to figure out which versions of Ruby on Rails run under which versions of Ruby. I couldn’t find a compatibility chart so I put this together:
| Rails Version | Possible Ruby Versions | Recommended Ruby Version |
|---|---|---|
| 1.0–2.1 | 1.8.6 | 1.8.6 |
| 2.2 | 1.8.6 or 1.8.7 | 1.8.7 |
| 2.3 | 1.8.6, 1.8.7, or 1.9.1 | 1.8.7 |
| 3.0–3.2 | 1.8.7, 1.9.2, or 1.9.3 | 1.9.3 |
| 4.0–… | 1.9.3 or 2.0.x | 2.0.x |
Updated: Rails 4.0 adds support for Ruby 2.0.