Model Comparison
Gemini 3 Flash vs GPT-5.1 Codex MiniWhich is better in 2026?
Gemini 3 Flash significantly outperforms across most benchmarks. GPT-5.1 Codex Mini is 1.6x cheaper per token.
Verdict: Gemini 3 Flash vs GPT-5.1 Codex Mini — which is better?
Gemini 3 Flash (by Google) and GPT-5.1 Codex Mini (by OpenAI) are two of the AI models people compare most. Here is how they stack up on benchmarks, price and capabilities, and which one to pick in 2026.
Gemini 3 Flash outperforms in 1 benchmarks (AIME 2025), while GPT-5.1 Codex Mini is better at 0 benchmarks. Gemini 3 Flash significantly outperforms across most benchmarks.
On price, GPT-5.1 Codex Mini is roughly 1.6x cheaper per token on a blended 3:1 input/output basis, which adds up quickly at production volume.
Gemini 3 Flash also accepts a larger context window (1,000,000 input tokens), making it the stronger choice for long documents and large codebases.
Choose Gemini 3 Flash if…
- you want the strongest raw capability — it leads on 1 of 1 shared benchmarks
- you process long inputs — it offers a 1,000,000 token context window
- you want the most recent training data — it shipped Dec 2025
Choose GPT-5.1 Codex Mini if…
- cost matters — it's about 1.6x cheaper per token
Performance Benchmarks
Comparative analysis across standard metrics
Gemini 3 Flash outperforms in 1 benchmarks (AIME 2025), while GPT-5.1 Codex Mini is better at 0 benchmarks.
Gemini 3 Flash significantly outperforms across most benchmarks.
Arena Performance
Human preference votes
Pricing Analysis
Price comparison per million tokens
For input processing, Gemini 3 Flash ($0.50/1M tokens) is 2.0x more expensive than GPT-5.1 Codex Mini ($0.25/1M tokens).
For output processing, Gemini 3 Flash ($3.00/1M tokens) is 1.5x more expensive than GPT-5.1 Codex Mini ($2.00/1M tokens).
In conclusion, Gemini 3 Flash is more expensive than GPT-5.1 Codex Mini.*
* Using a 3:1 ratio of input to output tokens
Context Window
Maximum input and output token capacity
Gemini 3 Flash accepts 1,000,000 input tokens compared to GPT-5.1 Codex Mini's 400,000 tokens. GPT-5.1 Codex Mini can generate longer responses up to 128,000 tokens, while Gemini 3 Flash is limited to 65,536 tokens.
Input Capabilities
Supported data types and modalities
Both Gemini 3 Flash and GPT-5.1 Codex Mini support multimodal inputs.
They are both capable of processing various types of data, offering versatility in application.
Gemini 3 Flash
GPT-5.1 Codex Mini
License
Usage and distribution terms
Both models are licensed under proprietary licenses.
Both models have usage restrictions defined by their respective organizations.
Proprietary
Closed source
Proprietary
Closed source
Release Timeline
When each model was launched
Gemini 3 Flash was released on 2025-12-17, while GPT-5.1 Codex Mini was released on 2025-11-12.
Gemini 3 Flash is 1 month newer than GPT-5.1 Codex Mini.
Dec 17, 2025
6 months ago
1mo newerNov 12, 2025
7 months ago
Knowledge Cutoff
When training data ends
Gemini 3 Flash has a documented knowledge cutoff of 2025-01-31, while GPT-5.1 Codex Mini's cutoff date is not specified.
We can confirm Gemini 3 Flash's training data extends to 2025-01-31, but cannot make a direct comparison without GPT-5.1 Codex Mini's cutoff date.
Jan 2025
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Provider Availability
Gemini 3 Flash is available from Google. GPT-5.1 Codex Mini is available from OpenAI.
Gemini 3 Flash
GPT-5.1 Codex Mini
Outputs Comparison
Key Takeaways
Detailed Comparison
Interactive Arena
Judge for yourself.
Run your own prompts against Gemini 3 Flash and GPT-5.1 Codex Mini side-by-side, then vote on the output you prefer.
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FAQ
Common questions about Gemini 3 Flash vs GPT-5.1 Codex Mini.