Model Comparison

GPT-5 Codex vs Phi-3.5-MoE-instructWhich is better in 2026?

Comparing GPT-5 Codex and Phi-3.5-MoE-instruct across benchmarks, pricing, and capabilities.

Verdict: GPT-5 Codex vs Phi-3.5-MoE-instruct — which is better?

GPT-5 Codex (by OpenAI) and Phi-3.5-MoE-instruct (by Microsoft) 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 GPT-5 Codex if…

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

Choose Phi-3.5-MoE-instruct if…

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

Performance Benchmarks

Comparative analysis across standard metrics

No common benchmarks found

GPT-5 Codex and Phi-3.5-MoE-instructdon't have any common benchmark datasets to compare. They may have been evaluated on different testing suites.

Arena Performance

Human preference votes

License

Usage and distribution terms

GPT-5 Codex is licensed under a proprietary license, while Phi-3.5-MoE-instruct uses MIT.

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

GPT-5 Codex

Proprietary

Closed source

Phi-3.5-MoE-instruct

MIT

Open weights

Release Timeline

When each model was launched

GPT-5 Codex was released on 2025-09-15, while Phi-3.5-MoE-instruct was released on 2024-08-23.

GPT-5 Codex is 13 months newer than Phi-3.5-MoE-instruct.

GPT-5 Codex

Sep 15, 2025

10 months ago

1.1yr newer
Phi-3.5-MoE-instruct

Aug 23, 2024

1.9 years ago

Knowledge Cutoff

When training data ends

GPT-5 Codex has a documented knowledge cutoff of 2024-09-30, while Phi-3.5-MoE-instruct'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 Phi-3.5-MoE-instruct's cutoff date.

GPT-5 Codex

Sep 2024

Phi-3.5-MoE-instruct

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Outputs Comparison

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Key Takeaways

OpenAI

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

Microsoft
Has open weights

Detailed Comparison

Interactive Arena

Judge for yourself.

Run your own prompts against GPT-5 Codex and Phi-3.5-MoE-instruct side-by-side, then vote on the output you prefer.

GPT-5 Codex
✓ Preferred
Phi-3.5-MoE-instruct
Open in Playground
AI Model Comparison Table
Feature
OpenAI
GPT-5 Codex
Microsoft
Phi-3.5-MoE-instruct

FAQ

Common questions about GPT-5 Codex vs Phi-3.5-MoE-instruct.

Which is better, GPT-5 Codex or Phi-3.5-MoE-instruct?

GPT-5 Codex (OpenAI) and Phi-3.5-MoE-instruct (Microsoft) each have strengths in different areas. Compare their benchmark scores, pricing, context windows, and capabilities above to determine which fits your needs.

How does GPT-5 Codex compare to Phi-3.5-MoE-instruct in benchmarks?

GPT-5 Codex scores SWE-Bench Verified: 74.5%. Phi-3.5-MoE-instruct scores ARC-C: 91.0%, OpenBookQA: 89.6%, GSM8k: 88.7%, PIQA: 88.6%, RULER: 87.1%.

What are the main differences between GPT-5 Codex and Phi-3.5-MoE-instruct?

Key differences include licensing (Proprietary vs MIT). See the full comparison above for benchmark-by-benchmark results.

Who makes GPT-5 Codex and Phi-3.5-MoE-instruct?

GPT-5 Codex is developed by OpenAI and Phi-3.5-MoE-instruct is developed by Microsoft.

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