Gemini 3 Pro vs GPT-5.1 Codex
Gemini 3 Pro and GPT-5.1 Codex are closely matched at 38.6 and 29.6 on the LLM Stats Score. GPT-5.1 Codex is 1.3x cheaper per token.
Google · OpenAI · Updated for 2026
Which is better?
Gemini 3 Pro and GPT-5.1 Codex are closely matched on the overall LLM Stats Score at 38.6 and 29.6.
In the 2 individual benchmarks reported for both models, Gemini 3 Pro wins 2; this is a narrower head-to-head signal than the composite indexes.
On price, GPT-5.1 Codex is roughly 1.3x cheaper per token on a blended 3:1 input/output basis, which adds up quickly at production volume.
Gemini 3 Pro 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 Pro
- you value its reported benchmark strengths — it wins 2 of 2 exact shared results
- you process long inputs — it offers a 1,048,576 token context window
Choose GPT-5.1 Codex
- cost matters — it's about 1.3x cheaper per token
- you want the most recent training data — it shipped Nov 2025
At a glance
The differences that matter most.
Individual benchmarks
21 reported for Gemini 3 Pro · 3 for GPT-5.1 Codex
Gemini 3 Pro outperforms in 2 benchmarks (SWE-Bench Verified, Terminal-Bench 2.0), while GPT-5.1 Codex is better at 0 benchmarks.
Gemini 3 Pro significantly outperforms across most benchmarks.
Human preference
Blind head-to-head votes and playground preference scores
Pricing Analysis
Price comparison per million tokens
For input processing, Gemini 3 Pro ($2.00/1M tokens) is 1.6x more expensive than GPT-5.1 Codex ($1.25/1M tokens).
For output processing, Gemini 3 Pro ($12.00/1M tokens) is 1.2x more expensive than GPT-5.1 Codex ($10.00/1M tokens).
In conclusion, Gemini 3 Pro is more expensive than GPT-5.1 Codex.*
* Using a 3:1 ratio of input to output tokens
Context Window
Maximum input and output token capacity
Gemini 3 Pro accepts 1,048,576 input tokens compared to GPT-5.1 Codex's 400,000 tokens. GPT-5.1 Codex can generate longer responses up to 128,000 tokens, while Gemini 3 Pro is limited to 65,536 tokens.
Input capabilities
Documented input modalities across available providers
Both Gemini 3 Pro and GPT-5.1 Codex support multimodal inputs.
They are both capable of processing various types of data, offering versatility in application.
Gemini 3 Pro
GPT-5.1 Codex
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 Pro was released on 2025-11-18, while GPT-5.1 Codex was released on 2025-11-19.
GPT-5.1 Codex is 0 month newer than Gemini 3 Pro.
Nov 18, 2025
9 months ago
Nov 19, 2025
9 months ago
1d newerKnowledge Cutoff
When training data ends
Gemini 3 Pro has a knowledge cutoff of 2025-01-31, while GPT-5.1 Codex has a cutoff of 2024-09-30.
Gemini 3 Pro has more recent training data (up to 2025-01-31), making it potentially better informed about events through that date compared to GPT-5.1 Codex (2024-09-30).
Jan 2025
4 mo newerSep 2024
Provider Availability
Gemini 3 Pro is available from Google. GPT-5.1 Codex is available from OpenAI.
Gemini 3 Pro
GPT-5.1 Codex
Outputs Comparison
Judge for yourself.
Run your own prompts against Gemini 3 Pro and GPT-5.1 Codex side-by-side, then vote on the output you prefer.
FAQ
Common questions about Gemini 3 Pro vs GPT-5.1 Codex.