OpenAI Codex Mini vs Gemini 2.5 Flash Preview

Compare OpenAI Codex Mini by OpenAI against Gemini 2.5 Flash Preview by Google AI, context windows of 200K vs 1.0M, tested across 8 shared challenges. Updated April 2026.

Which is better, OpenAI Codex Mini or Gemini 2.5 Flash Preview?

OpenAI Codex Mini and Gemini 2.5 Flash Preview are both competitive models. OpenAI Codex Mini costs $1.5/M input tokens vs $0.15/M for Gemini 2.5 Flash Preview. Context windows: 200K vs 1049K tokens. Compare their real outputs side by side below.

Key Differences Between OpenAI Codex Mini and Gemini 2.5 Flash Preview

OpenAI Codex Mini is made by openai while Gemini 2.5 Flash Preview is from google. OpenAI Codex Mini has a 200K token context window compared to Gemini 2.5 Flash Preview's 1049K. On pricing, OpenAI Codex Mini costs $1.5/M input tokens vs $0.15/M for Gemini 2.5 Flash Preview.

Our Verdict
OpenAI Codex Mini
OpenAI Codex Mini
Gemini 2.5 Flash Preview
Gemini 2.5 Flash Preview

No community votes yet. On paper, these are closely matched - try both with your actual task to see which fits your workflow.

Gemini 2.5 Flash Preview is 10x cheaper per token — worth considering if cost matters.

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OpenAI Codex MiniGemini 2.5 Flash Preview

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