Model Comparison

Claude Opus 5 vs GPT-5.1 Codex HighWhich is better in 2026?

Comparing Claude Opus 5 and GPT-5.1 Codex High across benchmarks, pricing, and capabilities.

Verdict: Claude Opus 5 vs GPT-5.1 Codex High — which is better?

Claude Opus 5 (by Anthropic) and GPT-5.1 Codex High (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 High is roughly 2.9x cheaper per token on a blended 3:1 input/output basis, which adds up quickly at production volume.

Claude Opus 5 also accepts a larger context window (1,000,000 input tokens), making it the stronger choice for long documents and large codebases.

Choose Claude Opus 5 if…

  • you process long inputs — it offers a 1,000,000 token context window
  • you want the most recent training data — it shipped Jul 2026

Choose GPT-5.1 Codex High if…

  • cost matters — it's about 2.9x cheaper per token

Performance Benchmarks

Comparative analysis across standard metrics

No common benchmarks found

Claude Opus 5 and GPT-5.1 Codex Highdon'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 High costs less

For input processing, Claude Opus 5 ($5.00/1M tokens) is 4.0x more expensive than GPT-5.1 Codex High ($1.25/1M tokens).

For output processing, Claude Opus 5 ($25.00/1M tokens) is 2.5x more expensive than GPT-5.1 Codex High ($10.00/1M tokens).

In conclusion, Claude Opus 5 is more expensive than GPT-5.1 Codex High.*

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

Lowest available price from all providers
Sun Jul 26 2026 • llm-stats.com
Anthropic
Claude Opus 5
Input tokens$5.00
Output tokens$25.00
Best providerAnthropic
OpenAI
GPT-5.1 Codex High
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

Claude Opus 5 accepts 1,000,000 input tokens compared to GPT-5.1 Codex High's 400,000 tokens. Both models can generate responses up to 128,000 tokens.

Anthropic
Claude Opus 5
Input1,000,000 tokens
Output128,000 tokens
OpenAI
GPT-5.1 Codex High
Input400,000 tokens
Output128,000 tokens
Sun Jul 26 2026 • llm-stats.com

Input Capabilities

Supported data types and modalities

Both Claude Opus 5 and GPT-5.1 Codex High support multimodal inputs.

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

Claude Opus 5

Text
Images
Audio
Video

GPT-5.1 Codex High

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 5

Proprietary

Closed source

GPT-5.1 Codex High

Proprietary

Closed source

Release Timeline

When each model was launched

Claude Opus 5 was released on 2026-07-24, while GPT-5.1 Codex High was released on 2025-11-12.

Claude Opus 5 is 8 months newer than GPT-5.1 Codex High.

Claude Opus 5

Jul 24, 2026

1 days ago

8mo newer
GPT-5.1 Codex High

Nov 12, 2025

8 months ago

Knowledge Cutoff

When training data ends

Neither model specifies a knowledge cutoff date.

Unable to compare the recency of their training data.

No cutoff dates available

Provider Availability

Claude Opus 5 is available from Anthropic. GPT-5.1 Codex High is available from OpenAI.

Claude Opus 5

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

GPT-5.1 Codex High

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

Outputs Comparison

Notice missing or incorrect data?Start an Issue discussion→

Key Takeaways

Anthropic
Larger context window (1,000,000 tokens)
OpenAI
Less expensive input tokens
Less expensive output tokens

Detailed Comparison

Interactive Arena

Judge for yourself.

Run your own prompts against Claude Opus 5 and GPT-5.1 Codex High side-by-side, then vote on the output you prefer.

Claude Opus 5
✓ Preferred
GPT-5.1 Codex High
Open in Playground
AI Model Comparison Table
Feature
Anthropic
Claude Opus 5
OpenAI
GPT-5.1 Codex High

FAQ

Common questions about Claude Opus 5 vs GPT-5.1 Codex High.

Which is better, Claude Opus 5 or GPT-5.1 Codex High?

Claude Opus 5 (Anthropic) and GPT-5.1 Codex High (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 5 compare to GPT-5.1 Codex High in benchmarks?

Claude Opus 5 scores BrowseComp: 90.8%, BioMysteryBench: 90.1%, OSWorld 2.0: 70.6%, DeepSWE 1.1: 68.8%, Humanity's Last Exam: 64.7%. GPT-5.1 Codex High scores AIME 2025: 96.7%.

Is Claude Opus 5 cheaper than GPT-5.1 Codex High?

GPT-5.1 Codex High is 4.0x cheaper for input tokens. Claude Opus 5 costs $5.00/M input and $25.00/M output via anthropic. GPT-5.1 Codex High costs $1.25/M input and $10.00/M output via openai.

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

Claude Opus 5 supports 1.0M tokens and GPT-5.1 Codex High 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 5 and GPT-5.1 Codex High?

Key differences include context window (1.0M vs 400K), input pricing ($5.00 vs $1.25/M). See the full comparison above for benchmark-by-benchmark results.

Who makes Claude Opus 5 and GPT-5.1 Codex High?

Claude Opus 5 is developed by Anthropic and GPT-5.1 Codex High is developed by OpenAI.

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