Gemini 3.8 Flash vs GPT-5.1 Codex High
Gemini 3.8 Flash leads the LLM Stats Score 50.6 to 29.4. Gemini 3.8 Flash is 2.3x cheaper per token.
Google · OpenAI · Updated for 2026
Which is better?
Gemini 3.8 Flash leads the overall LLM Stats Score 50.6 to 29.4, ranking #16 overall.
On price, Gemini 3.8 Flash is roughly 2.3x cheaper per token on a blended 3:1 input/output basis, which adds up quickly at production volume.
Gemini 3.8 Flash also accepts a larger context window (1,048,576 input tokens), making it the stronger choice for long documents and large codebases.
Based on current LLM Stats indexes, shared benchmarks, pricing, and model metadata for 2026.
Choose Gemini 3.8 Flash
- overall performance matters — it scores 50.6 and ranks #16 on LLM Stats
- your work emphasizes reasoning — it leads those capability indexes
- cost matters — it's about 2.3x 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 Sep 2026
Choose GPT-5.1 Codex High
- you want predictable pricing at $1.25/M input and $10.00/M output
At a glance
The differences that matter most.
Individual benchmarks
13 reported for Gemini 3.8 Flash · 1 for GPT-5.1 Codex High
Gemini 3.8 Flash and GPT-5.1 Codex Highdon't have any common benchmark datasets to compare. They may have been evaluated on different testing suites.
Human preference
Blind head-to-head votes and playground preference scores
Pricing Analysis
Price comparison per million tokens
For input processing, Gemini 3.8 Flash ($0.75/1M tokens) is 1.7x cheaper than GPT-5.1 Codex High ($1.25/1M tokens).
For output processing, Gemini 3.8 Flash ($3.75/1M tokens) is 2.7x cheaper than GPT-5.1 Codex High ($10.00/1M tokens).
In conclusion, GPT-5.1 Codex High is more expensive than Gemini 3.8 Flash.*
* Using a 3:1 ratio of input to output tokens
Context Window
Maximum input and output token capacity
Gemini 3.8 Flash 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 3.8 Flash is limited to 65,536 tokens.
Input capabilities
Documented input modalities across available providers
Both Gemini 3.8 Flash and GPT-5.1 Codex High support multimodal inputs.
They are both capable of processing various types of data, offering versatility in application.
Gemini 3.8 Flash
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 3.8 Flash was released on 2026-09-02, while GPT-5.1 Codex High was released on 2025-11-12.
Gemini 3.8 Flash is 10 months newer than GPT-5.1 Codex High.
Sep 2, 2026
1 weeks ago
9mo newerNov 12, 2025
10 months ago
Knowledge Cutoff
When training data ends
Gemini 3.8 Flash 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 3.8 Flash'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 3.8 Flash is available from Google. GPT-5.1 Codex High is available from OpenAI.
Gemini 3.8 Flash
GPT-5.1 Codex High
Outputs Comparison
Judge for yourself.
Run your own prompts against Gemini 3.8 Flash and GPT-5.1 Codex High side-by-side, then vote on the output you prefer.
FAQ
Common questions about Gemini 3.8 Flash vs GPT-5.1 Codex High.