Model Comparison

Claude Opus 4.5 vs GPT-5.1 Codex MiniWhich is better in 2026?

Comparing Claude Opus 4.5 and GPT-5.1 Codex Mini across benchmarks, pricing, and capabilities.

Verdict: Claude Opus 4.5 vs GPT-5.1 Codex Mini — which is better?

Claude Opus 4.5 (by Anthropic) and GPT-5.1 Codex Mini (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.

On price, GPT-5.1 Codex Mini is roughly 14.5x cheaper per token on a blended 3:1 input/output basis, which adds up quickly at production volume.

GPT-5.1 Codex Mini also accepts a larger context window (400,000 input tokens), making it the stronger choice for long documents and large codebases.

Choose Claude Opus 4.5 if…

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

Choose GPT-5.1 Codex Mini if…

  • cost matters — it's about 14.5x cheaper per token
  • you process long inputs — it offers a 400,000 token context window

Performance Benchmarks

Comparative analysis across standard metrics

No common benchmarks found

Claude Opus 4.5 and GPT-5.1 Codex Minidon't have any common benchmark datasets to compare. They may have been evaluated on different testing suites.

Arena Performance

Human preference votes

Pricing Analysis

Price comparison per million tokens

GPT-5.1 Codex Mini costs less

For input processing, Claude Opus 4.5 ($5.00/1M tokens) is 20.0x more expensive than GPT-5.1 Codex Mini ($0.25/1M tokens).

For output processing, Claude Opus 4.5 ($25.00/1M tokens) is 12.5x more expensive than GPT-5.1 Codex Mini ($2.00/1M tokens).

In conclusion, Claude Opus 4.5 is more expensive than GPT-5.1 Codex Mini.*

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

Lowest available price from all providers
Fri Jun 26 2026 • llm-stats.com
Anthropic
Claude Opus 4.5
Input tokens$5.00
Output tokens$25.00
Best providerAnthropic
OpenAI
GPT-5.1 Codex Mini
Input tokens$0.25
Output tokens$2.00
Best providerOpenAI
Notice missing or incorrect data?Start an Issue→

Context Window

Maximum input and output token capacity

GPT-5.1 Codex Mini accepts 400,000 input tokens compared to Claude Opus 4.5's 200,000 tokens. GPT-5.1 Codex Mini can generate longer responses up to 128,000 tokens, while Claude Opus 4.5 is limited to 64,000 tokens.

Anthropic
Claude Opus 4.5
Input200,000 tokens
Output64,000 tokens
OpenAI
GPT-5.1 Codex Mini
Input400,000 tokens
Output128,000 tokens
Fri Jun 26 2026 • llm-stats.com

Input Capabilities

Supported data types and modalities

Both Claude Opus 4.5 and GPT-5.1 Codex Mini support multimodal inputs.

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

Claude Opus 4.5

Text
Images
Audio
Video

GPT-5.1 Codex Mini

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.

Claude Opus 4.5

Proprietary

Closed source

GPT-5.1 Codex Mini

Proprietary

Closed source

Release Timeline

When each model was launched

Claude Opus 4.5 was released on 2025-11-24, while GPT-5.1 Codex Mini was released on 2025-11-12.

Claude Opus 4.5 is 0 month newer than GPT-5.1 Codex Mini.

Claude Opus 4.5

Nov 24, 2025

7 months ago

1w newer
GPT-5.1 Codex Mini

Nov 12, 2025

7 months ago

Knowledge Cutoff

When training data ends

Claude Opus 4.5 has a documented knowledge cutoff of 2025-03-31, while GPT-5.1 Codex Mini's cutoff date is not specified.

We can confirm Claude Opus 4.5's training data extends to 2025-03-31, but cannot make a direct comparison without GPT-5.1 Codex Mini's cutoff date.

Claude Opus 4.5

Mar 2025

GPT-5.1 Codex Mini

—

Provider Availability

Claude Opus 4.5 is available from Anthropic. GPT-5.1 Codex Mini is available from OpenAI.

Claude Opus 4.5

anthropic logo
Anthropic
Input Price:Input: $5.00/1MOutput Price:Output: $25.00/1M

GPT-5.1 Codex Mini

openai logo
OpenAI
Input Price:Input: $0.25/1MOutput Price:Output: $2.00/1M
* Prices shown are per million tokens

Outputs Comparison

Notice missing or incorrect data?Start an Issue discussion→

Key Takeaways

Anthropic

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

OpenAI
Larger context window (400,000 tokens)
Less expensive input tokens
Less expensive output tokens

Detailed Comparison

Interactive Arena

Judge for yourself.

Run your own prompts against Claude Opus 4.5 and GPT-5.1 Codex Mini side-by-side, then vote on the output you prefer.

Claude Opus 4.5
✓ Preferred
GPT-5.1 Codex Mini
Open in Playground
AI Model Comparison Table
Feature
Anthropic
Claude Opus 4.5
OpenAI
GPT-5.1 Codex Mini

FAQ

Common questions about Claude Opus 4.5 vs GPT-5.1 Codex Mini.

Which is better, Claude Opus 4.5 or GPT-5.1 Codex Mini?

Claude Opus 4.5 (Anthropic) and GPT-5.1 Codex Mini (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 Claude Opus 4.5 compare to GPT-5.1 Codex Mini in benchmarks?

Claude Opus 4.5 scores Tau2 Telecom: 98.2%, MMMLU: 90.8%, Tau2 Retail: 88.9%, GPQA: 87.0%, SWE-Bench Verified: 80.9%. GPT-5.1 Codex Mini scores AIME 2025: 42.1%.

Is Claude Opus 4.5 cheaper than GPT-5.1 Codex Mini?

GPT-5.1 Codex Mini is 20.0x cheaper for input tokens. Claude Opus 4.5 costs $5.00/M input and $25.00/M output via anthropic. GPT-5.1 Codex Mini costs $0.25/M input and $2.00/M output via openai.

What are the context window sizes for Claude Opus 4.5 and GPT-5.1 Codex Mini?

Claude Opus 4.5 supports 200K tokens and GPT-5.1 Codex Mini supports 400K tokens. A larger context window lets you process longer documents, conversations, or codebases in a single request.

What are the main differences between Claude Opus 4.5 and GPT-5.1 Codex Mini?

Key differences include context window (200K vs 400K), input pricing ($5.00 vs $0.25/M). See the full comparison above for benchmark-by-benchmark results.

Who makes Claude Opus 4.5 and GPT-5.1 Codex Mini?

Claude Opus 4.5 is developed by Anthropic and GPT-5.1 Codex Mini is developed by OpenAI.

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