Model Comparison

Claude Opus 4.8 vs GPT-5.6 LunaWhich is better in 2026?

Claude Opus 4.8 significantly outperforms across most benchmarks. GPT-5.6 Luna is 4.4x cheaper per token.

Verdict: Claude Opus 4.8 vs GPT-5.6 Luna — which is better?

Claude Opus 4.8 (by Anthropic) and GPT-5.6 Luna (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.

Claude Opus 4.8 outperforms in 6 benchmarks (BrowseComp, GDPval-AA, GPQA, HealthBench Professional, SWE-Bench Pro, Toolathlon), while GPT-5.6 Luna is better at 1 benchmark (Graphwalks BFS >128k). Claude Opus 4.8 significantly outperforms across most benchmarks.

On price, GPT-5.6 Luna is roughly 4.4x cheaper per token on a blended 3:1 input/output basis, which adds up quickly at production volume.

GPT-5.6 Luna also accepts a larger context window (1,050,000 input tokens), making it the stronger choice for long documents and large codebases.

Choose Claude Opus 4.8 if…

  • you want the strongest raw capability — it leads on 6 of 7 shared benchmarks

Choose GPT-5.6 Luna if…

  • cost matters — it's about 4.4x cheaper per token
  • you process long inputs — it offers a 1,050,000 token context window
  • you want the most recent training data — it shipped Jul 2026

Performance Benchmarks

Comparative analysis across standard metrics

7 benchmarks

Claude Opus 4.8 outperforms in 6 benchmarks (BrowseComp, GDPval-AA, GPQA, HealthBench Professional, SWE-Bench Pro, Toolathlon), while GPT-5.6 Luna is better at 1 benchmark (Graphwalks BFS >128k).

Claude Opus 4.8 significantly outperforms across most benchmarks.

Fri Jul 17 2026 • llm-stats.com

Arena Performance

Human preference votes

Pricing Analysis

Price comparison per million tokens

GPT-5.6 Luna costs less

For input processing, Claude Opus 4.8 ($5.00/1M tokens) is 5.0x more expensive than GPT-5.6 Luna ($1.00/1M tokens).

For output processing, Claude Opus 4.8 ($25.00/1M tokens) is 4.2x more expensive than GPT-5.6 Luna ($6.00/1M tokens).

In conclusion, Claude Opus 4.8 is more expensive than GPT-5.6 Luna.*

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

Lowest available price from all providers
Fri Jul 17 2026 • llm-stats.com
Anthropic
Claude Opus 4.8
Input tokens$5.00
Output tokens$25.00
Best providerAnthropic
OpenAI
GPT-5.6 Luna
Input tokens$1.00
Output tokens$6.00
Best providerOpenAI
Notice missing or incorrect data?Start an Issue→

Context Window

Maximum input and output token capacity

GPT-5.6 Luna accepts 1,050,000 input tokens compared to Claude Opus 4.8's 1,000,000 tokens. Both models can generate responses up to 128,000 tokens.

Anthropic
Claude Opus 4.8
Input1,000,000 tokens
Output128,000 tokens
OpenAI
GPT-5.6 Luna
Input1,050,000 tokens
Output128,000 tokens
Fri Jul 17 2026 • llm-stats.com

Input Capabilities

Supported data types and modalities

Both Claude Opus 4.8 and GPT-5.6 Luna support multimodal inputs.

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

Claude Opus 4.8

Text
Images
Audio
Video

GPT-5.6 Luna

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 4.8

Proprietary

Closed source

GPT-5.6 Luna

Proprietary

Closed source

Release Timeline

When each model was launched

Claude Opus 4.8 was released on 2026-05-28, while GPT-5.6 Luna was released on 2026-07-09.

GPT-5.6 Luna is 1 month newer than Claude Opus 4.8.

Claude Opus 4.8

May 28, 2026

1 months ago

GPT-5.6 Luna

Jul 9, 2026

1 weeks ago

1mo newer

Knowledge Cutoff

When training data ends

GPT-5.6 Luna has a documented knowledge cutoff of 2026-02-16, while Claude Opus 4.8's cutoff date is not specified.

We can confirm GPT-5.6 Luna's training data extends to 2026-02-16, but cannot make a direct comparison without Claude Opus 4.8's cutoff date.

Claude Opus 4.8

—

GPT-5.6 Luna

Feb 2026

Provider Availability

Claude Opus 4.8 is available from Anthropic, Vertex AI. GPT-5.6 Luna is available from OpenAI.

Claude Opus 4.8

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

GPT-5.6 Luna

openai logo
OpenAI
Input Price:Input: $1.00/1MOutput Price:Output: $6.00/1M
* Prices shown are per million tokens

Outputs Comparison

Notice missing or incorrect data?Start an Issue discussion→

Key Takeaways

Anthropic
Higher BrowseComp score (84.3% vs 83.3%)
Higher GDPval-AA score (54.6% vs 53.1%)
Higher GPQA score (93.6% vs 92.3%)
Higher HealthBench Professional score (55.8% vs 55.7%)
Higher SWE-Bench Pro score (69.2% vs 62.7%)
Higher Toolathlon score (59.9% vs 53.4%)
OpenAI
Larger context window (1,050,000 tokens)
Less expensive input tokens
Less expensive output tokens
Higher Graphwalks BFS >128k score (81.3% vs 68.1%)

Detailed Comparison

Interactive Arena

Judge for yourself.

Run your own prompts against Claude Opus 4.8 and GPT-5.6 Luna side-by-side, then vote on the output you prefer.

Claude Opus 4.8
✓ Preferred
GPT-5.6 Luna
Open in Playground
AI Model Comparison Table
Feature
Anthropic
Claude Opus 4.8
OpenAI
GPT-5.6 Luna

FAQ

Common questions about Claude Opus 4.8 vs GPT-5.6 Luna.

Which is better, Claude Opus 4.8 or GPT-5.6 Luna?

Claude Opus 4.8 significantly outperforms across most benchmarks. Claude Opus 4.8 is made by Anthropic and GPT-5.6 Luna is made by OpenAI. The best choice depends on your use case — compare their benchmark scores, pricing, and capabilities above.

How does Claude Opus 4.8 compare to GPT-5.6 Luna in benchmarks?

Claude Opus 4.8 scores GPQA: 93.6%, DeepSearchQA: 93.1%, CharXiv-R: 89.9%, SWE-Bench Verified: 88.6%, ScreenSpot Pro: 87.9%. GPT-5.6 Luna scores Connectors: 99.9%, HealthBench Consensus: 95.1%, GPQA: 92.3%, Search and Function-Calling: 89.7%, Capture-the-Flag Challenges (Internal): 85.2%.

Is Claude Opus 4.8 cheaper than GPT-5.6 Luna?

GPT-5.6 Luna is 5.0x cheaper for input tokens. Claude Opus 4.8 costs $5.00/M input and $25.00/M output via anthropic. GPT-5.6 Luna costs $1.00/M input and $6.00/M output via openai.

What are the context window sizes for Claude Opus 4.8 and GPT-5.6 Luna?

Claude Opus 4.8 supports 1.0M tokens and GPT-5.6 Luna supports 1.1M 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 4.8 and GPT-5.6 Luna?

Key differences include context window (1.0M vs 1.1M), input pricing ($5.00 vs $1.00/M). See the full comparison above for benchmark-by-benchmark results.

Who makes Claude Opus 4.8 and GPT-5.6 Luna?

Claude Opus 4.8 is developed by Anthropic and GPT-5.6 Luna is developed by OpenAI.

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