Model Comparison

GPT-5 vs GPT-5.1 Codex

GPT-5 significantly outperforms across most benchmarks. GPT-5 and GPT-5.1 Codex cost the same.

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Performance Benchmarks

Comparative analysis across standard metrics

1 benchmarks

GPT-5 outperforms in 1 benchmarks (SWE-Bench Verified), while GPT-5.1 Codex is better at 0 benchmarks.

GPT-5 significantly outperforms across most benchmarks.

Sat May 30 2026 • llm-stats.com

Arena Performance

Human preference votes

Pricing Analysis

Price comparison per million tokens

For input processing, GPT-5 ($1.25/1M tokens) costs the same as GPT-5.1 Codex ($1.25/1M tokens).

For output processing, GPT-5 ($10.00/1M tokens) costs the same as GPT-5.1 Codex ($10.00/1M tokens).

In conclusion, GPT-5 and GPT-5.1 Codex cost the same.*

* Using a 3:1 ratio of input to output tokens

Lowest available price from all providers
Sat May 30 2026 • llm-stats.com
OpenAI
GPT-5
Input tokens$1.25
Output tokens$10.00
Best providerOpenAI
OpenAI
GPT-5.1 Codex
Input tokens$1.25
Output tokens$10.00
Best providerOpenAI
Notice missing or incorrect data?Start an Issue→

Context Window

Maximum input and output token capacity

Both models have the same input context window of 400,000 tokens. Both models can generate responses up to 128,000 tokens.

OpenAI
GPT-5
Input400,000 tokens
Output128,000 tokens
OpenAI
GPT-5.1 Codex
Input400,000 tokens
Output128,000 tokens
Sat May 30 2026 • llm-stats.com

Input Capabilities

Supported data types and modalities

Both GPT-5 and GPT-5.1 Codex support multimodal inputs.

They are both capable of processing various types of data, offering versatility in application.

GPT-5

Text
Images
Audio
Video

GPT-5.1 Codex

Text
Images
Audio
Video

License

Usage and distribution terms

Both models are licensed under proprietary licenses.

Both models have usage restrictions defined by their respective organizations.

GPT-5

Proprietary

Closed source

GPT-5.1 Codex

Proprietary

Closed source

Release Timeline

When each model was launched

GPT-5 was released on 2025-08-07, while GPT-5.1 Codex was released on 2025-11-19.

GPT-5.1 Codex is 3 months newer than GPT-5.

GPT-5

Aug 7, 2025

9 months ago

GPT-5.1 Codex

Nov 19, 2025

6 months ago

3mo newer

Knowledge Cutoff

When training data ends

Both models have the same knowledge cutoff date of 2024-09-30.

They should have similar awareness of historical events and information up to this date.

GPT-5

Sep 2024

GPT-5.1 Codex

Sep 2024

Provider Availability

GPT-5 is available from OpenAI. GPT-5.1 Codex is available from OpenAI.

GPT-5

openai logo
OpenAI
Input Price:Input: $1.25/1MOutput Price:Output: $10.00/1M

GPT-5.1 Codex

openai logo
OpenAI
Input Price:Input: $1.25/1MOutput Price:Output: $10.00/1M
* Prices shown are per million tokens

Outputs Comparison

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Key Takeaways

OpenAI
Higher SWE-Bench Verified score (74.9% vs 73.7%)
OpenAI

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

Detailed Comparison

AI Model Comparison Table
Feature
OpenAI
GPT-5
OpenAI
GPT-5.1 Codex

FAQ

Common questions about GPT-5 vs GPT-5.1 Codex.

Which is better, GPT-5 or GPT-5.1 Codex?

GPT-5 significantly outperforms across most benchmarks. GPT-5 is made by OpenAI and GPT-5.1 Codex is made by OpenAI. The best choice depends on your use case — compare their benchmark scores, pricing, and capabilities above.

How does GPT-5 compare to GPT-5.1 Codex in benchmarks?

GPT-5 scores SWE-Lancer (IC-Diamond subset): 100.0%, COLLIE: 99.0%, Tau2 Telecom: 96.7%, OpenAI-MRCR: 2 needle 128k: 95.2%, AIME 2025: 94.6%. GPT-5.1 Codex scores SWE-Bench Verified: 73.7%, SWE-Lancer: 66.3%, Terminal-Bench 2.0: 52.8%.

Is GPT-5 cheaper than GPT-5.1 Codex?

Both models cost $1.25 per million input tokens.

What are the context window sizes for GPT-5 and GPT-5.1 Codex?

GPT-5 supports 400K tokens and GPT-5.1 Codex supports 400K tokens. A larger context window lets you process longer documents, conversations, or codebases in a single request.