Model Comparison

Gemma 3 12B vs GPT-5 CodexWhich is better in 2026?

Comparing Gemma 3 12B and GPT-5 Codex across benchmarks, pricing, and capabilities.

Verdict: Gemma 3 12B vs GPT-5 Codex — which is better?

Gemma 3 12B (by Google) and GPT-5 Codex (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.

Choose Gemma 3 12B if…

  • you need open weights you can self-host or fine-tune

Choose GPT-5 Codex if…

  • you want the most recent training data — it shipped Sep 2025
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Performance Benchmarks

Comparative analysis across standard metrics

No common benchmarks found

Gemma 3 12B and GPT-5 Codexdon't have any common benchmark datasets to compare. They may have been evaluated on different testing suites.

Arena Performance

Human preference votes

Context Window

Maximum input and output token capacity

Only Gemma 3 12B specifies input context (131,072 tokens). Only Gemma 3 12B specifies output context (131,072 tokens).

Google
Gemma 3 12B
Input131,072 tokens
Output131,072 tokens
OpenAI
GPT-5 Codex
Input- tokens
Output- tokens
Thu Jun 11 2026 • llm-stats.com

Input Capabilities

Supported data types and modalities

Gemma 3 12B supports multimodal inputs, whereas GPT-5 Codex does not.

Gemma 3 12B can handle both text and other forms of data like images, making it suitable for multimodal applications.

Gemma 3 12B

Text
Images
Audio
Video

GPT-5 Codex

Text
Images
Audio
Video

License

Usage and distribution terms

Gemma 3 12B is licensed under Gemma, while GPT-5 Codex uses a proprietary license.

License differences may affect how you can use these models in commercial or open-source projects.

Gemma 3 12B

Gemma

Open weights

GPT-5 Codex

Proprietary

Closed source

Release Timeline

When each model was launched

Gemma 3 12B was released on 2025-03-12, while GPT-5 Codex was released on 2025-09-15.

GPT-5 Codex is 6 months newer than Gemma 3 12B.

Gemma 3 12B

Mar 12, 2025

1.2 years ago

GPT-5 Codex

Sep 15, 2025

8 months ago

6mo newer

Knowledge Cutoff

When training data ends

GPT-5 Codex has a documented knowledge cutoff of 2024-09-30, while Gemma 3 12B's cutoff date is not specified.

We can confirm GPT-5 Codex's training data extends to 2024-09-30, but cannot make a direct comparison without Gemma 3 12B's cutoff date.

Gemma 3 12B

—

GPT-5 Codex

Sep 2024

Outputs Comparison

Notice missing or incorrect data?Start an Issue discussion→

Key Takeaways

Google
Larger context window (131,072 tokens)
Supports multimodal inputs
Has open weights
OpenAI

No standout differentiators in the data we have for this pair.

Detailed Comparison

AI Model Comparison Table
Feature
Google
Gemma 3 12B
OpenAI
GPT-5 Codex

FAQ

Common questions about Gemma 3 12B vs GPT-5 Codex.

Which is better, Gemma 3 12B or GPT-5 Codex?

Gemma 3 12B (Google) and GPT-5 Codex (OpenAI) each have strengths in different areas. Compare their benchmark scores, pricing, context windows, and capabilities above to determine which fits your needs.

How does Gemma 3 12B compare to GPT-5 Codex in benchmarks?

Gemma 3 12B scores GSM8k: 94.4%, IFEval: 88.9%, DocVQA: 87.1%, BIG-Bench Hard: 85.7%, HumanEval: 85.4%. GPT-5 Codex scores SWE-Bench Verified: 74.5%.

What are the context window sizes for Gemma 3 12B and GPT-5 Codex?

Gemma 3 12B supports 131K tokens and GPT-5 Codex supports an unknown number of tokens. A larger context window lets you process longer documents, conversations, or codebases in a single request.

What are the main differences between Gemma 3 12B and GPT-5 Codex?

Key differences include multimodal support (yes vs no), licensing (Gemma vs Proprietary). See the full comparison above for benchmark-by-benchmark results.

Who makes Gemma 3 12B and GPT-5 Codex?

Gemma 3 12B is developed by Google and GPT-5 Codex is developed by OpenAI.

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