Gemini 2.5 Flash Preview vs GPT-5.1-Codex
Compare Gemini 2.5 Flash Preview by Google AI against GPT-5.1-Codex by OpenAI, context windows of 1.0M vs 400K, tested across 27 shared challenges. Updated April 2026.
Which is better, Gemini 2.5 Flash Preview or GPT-5.1-Codex?
Gemini 2.5 Flash Preview and GPT-5.1-Codex are both competitive models. Gemini 2.5 Flash Preview costs $0.15/M input tokens vs $1.25/M for GPT-5.1-Codex. Context windows: 1049K vs 400K tokens. Compare their real outputs side by side below.
Key Differences Between Gemini 2.5 Flash Preview and GPT-5.1-Codex
Gemini 2.5 Flash Preview is made by google while GPT-5.1-Codex is from openai. Gemini 2.5 Flash Preview has a 1049K token context window compared to GPT-5.1-Codex's 400K. On pricing, Gemini 2.5 Flash Preview costs $0.15/M input tokens vs $1.25/M for GPT-5.1-Codex.
No community votes yet. On paper, GPT-5.1-Codex has the edge — bigger model tier, newer.
Gemini 2.5 Flash Preview is 17x cheaper per token — worth considering if cost matters.
Style Comparison
GPT-5.1-Codex uses 5.7x more headings
vsAsk them anything yourself
Some models write identically. You are paying for the brand.
178 models fingerprinted across 32 writing dimensions. Free research.
185x
price gap between models that write identically
178
models
12
clone pairs
32
dimensions
279 AI models invented the same fake scientist.
We read every word. 250 models. 2.14 million words. This is what we found.
