Model Comparison
Gemini 3.5 Flash-Lite vs GPT-5.1 Codex HighWhich is better in 2026?
Comparing Gemini 3.5 Flash-Lite and GPT-5.1 Codex High across benchmarks, pricing, and capabilities.
Verdict: Gemini 3.5 Flash-Lite vs GPT-5.1 Codex High — which is better?
Gemini 3.5 Flash-Lite (by Google) and GPT-5.1 Codex High (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.
On price, Gemini 3.5 Flash-Lite is roughly 4.0x cheaper per token on a blended 3:1 input/output basis, which adds up quickly at production volume.
Gemini 3.5 Flash-Lite also accepts a larger context window (1,048,576 input tokens), making it the stronger choice for long documents and large codebases.
Choose Gemini 3.5 Flash-Lite if…
- cost matters — it's about 4.0x cheaper per token
- you process long inputs — it offers a 1,048,576 token context window
- you want the most recent training data — it shipped Jul 2026
Choose GPT-5.1 Codex High if…
- you want predictable pricing at $1.25/M input and $10.00/M output
Performance Benchmarks
Comparative analysis across standard metrics
Gemini 3.5 Flash-Lite and GPT-5.1 Codex Highdon't have any common benchmark datasets to compare. They may have been evaluated on different testing suites.
Arena Performance
Human preference votes
Pricing Analysis
Price comparison per million tokens
For input processing, Gemini 3.5 Flash-Lite ($0.30/1M tokens) is 4.2x cheaper than GPT-5.1 Codex High ($1.25/1M tokens).
For output processing, Gemini 3.5 Flash-Lite ($2.50/1M tokens) is 4.0x cheaper than GPT-5.1 Codex High ($10.00/1M tokens).
In conclusion, GPT-5.1 Codex High is more expensive than Gemini 3.5 Flash-Lite.*
* Using a 3:1 ratio of input to output tokens
Context Window
Maximum input and output token capacity
Gemini 3.5 Flash-Lite accepts 1,048,576 input tokens compared to GPT-5.1 Codex High's 400,000 tokens. GPT-5.1 Codex High can generate longer responses up to 128,000 tokens, while Gemini 3.5 Flash-Lite is limited to 65,536 tokens.
Input Capabilities
Supported data types and modalities
Both Gemini 3.5 Flash-Lite and GPT-5.1 Codex High support multimodal inputs.
They are both capable of processing various types of data, offering versatility in application.
Gemini 3.5 Flash-Lite
GPT-5.1 Codex High
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 3.5 Flash-Lite was released on 2026-07-21, while GPT-5.1 Codex High was released on 2025-11-12.
Gemini 3.5 Flash-Lite is 8 months newer than GPT-5.1 Codex High.
Jul 21, 2026
1 days ago
8mo newerNov 12, 2025
8 months ago
Knowledge Cutoff
When training data ends
Gemini 3.5 Flash-Lite has a documented knowledge cutoff of 2026-03-31, while GPT-5.1 Codex High's cutoff date is not specified.
We can confirm Gemini 3.5 Flash-Lite's training data extends to 2026-03-31, but cannot make a direct comparison without GPT-5.1 Codex High's cutoff date.
Mar 2026
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Provider Availability
Gemini 3.5 Flash-Lite is available from Google. GPT-5.1 Codex High is available from OpenAI.
Gemini 3.5 Flash-Lite
GPT-5.1 Codex High
Outputs Comparison
Key Takeaways
No standout differentiators in the data we have for this pair.
Detailed Comparison
Interactive Arena
Judge for yourself.
Run your own prompts against Gemini 3.5 Flash-Lite and GPT-5.1 Codex High side-by-side, then vote on the output you prefer.
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FAQ
Common questions about Gemini 3.5 Flash-Lite vs GPT-5.1 Codex High.