OpenAI Codex models explained
TL;DR Four tiers and a 50× price gap. Start on Terra and use the lowest effort level that still works.
Most people leave Codex on the biggest model and overpay. There are four tiers now, and here's when to use which.
- 💨 Luna: fast and cheap. Extraction, classification, reformatting at volume
- ⚡ Terra: the everyday all-rounder. Start here
- 🧠 Sol: complex code changes and deep research
- 🚀 Astra: the new ceiling. Only when Sol falls short
Try this
Codex has six effort levels. OpenAI's own advice: use the lowest one that works.
Sources: Prices per 1M tokens, September 2026.
