Model Comparison

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

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

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

Claude Opus 4.5 (by Anthropic) and GPT-5.1 Medium (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 Medium is roughly 2.9x cheaper per token on a blended 3:1 input/output basis, which adds up quickly at production volume.

GPT-5.1 Medium 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 Medium if…

  • cost matters — it's about 2.9x cheaper per token
  • you process long inputs — it offers a 400,000 token context window
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Performance Benchmarks

Comparative analysis across standard metrics

No common benchmarks found

Claude Opus 4.5 and GPT-5.1 Mediumdon'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 Medium costs less

For input processing, Claude Opus 4.5 ($5.00/1M tokens) is 4.0x more expensive than GPT-5.1 Medium ($1.25/1M tokens).

For output processing, Claude Opus 4.5 ($25.00/1M tokens) is 2.5x more expensive than GPT-5.1 Medium ($10.00/1M tokens).

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

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

Lowest available price from all providers
Wed Jun 24 2026 • llm-stats.com
Anthropic
Claude Opus 4.5
Input tokens$5.00
Output tokens$25.00
Best providerAnthropic
OpenAI
GPT-5.1 Medium
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

GPT-5.1 Medium accepts 400,000 input tokens compared to Claude Opus 4.5's 200,000 tokens. GPT-5.1 Medium 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 Medium
Input400,000 tokens
Output128,000 tokens
Wed Jun 24 2026 • llm-stats.com

Input Capabilities

Supported data types and modalities

Both Claude Opus 4.5 and GPT-5.1 Medium 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 Medium

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 Medium

Proprietary

Closed source

Release Timeline

When each model was launched

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

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

Claude Opus 4.5

Nov 24, 2025

7 months ago

1w newer
GPT-5.1 Medium

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 Medium'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 Medium's cutoff date.

Claude Opus 4.5

Mar 2025

GPT-5.1 Medium

—

Provider Availability

Claude Opus 4.5 is available from Anthropic. GPT-5.1 Medium 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 Medium

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

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

AI Model Comparison Table
Feature
Anthropic
Claude Opus 4.5
OpenAI
GPT-5.1 Medium

FAQ

Common questions about Claude Opus 4.5 vs GPT-5.1 Medium.

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

Claude Opus 4.5 (Anthropic) and GPT-5.1 Medium (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 Medium 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 Medium scores AIME 2025: 98.4%.

Is Claude Opus 4.5 cheaper than GPT-5.1 Medium?

GPT-5.1 Medium is 4.0x cheaper for input tokens. Claude Opus 4.5 costs $5.00/M input and $25.00/M output via anthropic. GPT-5.1 Medium costs $1.25/M input and $10.00/M output via openai.

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

Claude Opus 4.5 supports 200K tokens and GPT-5.1 Medium 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 Medium?

Key differences include context window (200K vs 400K), input pricing ($5.00 vs $1.25/M). See the full comparison above for benchmark-by-benchmark results.

Who makes Claude Opus 4.5 and GPT-5.1 Medium?

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

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