Model Comparison

Claude Fable 5 vs GPT-5.6 LunaWhich is better in 2026?

Claude Fable 5 significantly outperforms across most benchmarks. GPT-5.6 Luna is 8.9x cheaper per token.

Verdict: Claude Fable 5 vs GPT-5.6 Luna — which is better?

Claude Fable 5 (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 Fable 5 outperforms in 6 benchmarks (AutomationBench, ExploitBench, GDP.pdf, GDPval-AA, HealthBench Professional, SWE-Bench Pro), while GPT-5.6 Luna is better at 1 benchmark (Terminal-Bench 2.1). Claude Fable 5 significantly outperforms across most benchmarks.

On price, GPT-5.6 Luna is roughly 8.9x 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 Fable 5 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 8.9x 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 Fable 5 outperforms in 6 benchmarks (AutomationBench, ExploitBench, GDP.pdf, GDPval-AA, HealthBench Professional, SWE-Bench Pro), while GPT-5.6 Luna is better at 1 benchmark (Terminal-Bench 2.1).

Claude Fable 5 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 Fable 5 ($10.00/1M tokens) is 10.0x more expensive than GPT-5.6 Luna ($1.00/1M tokens).

For output processing, Claude Fable 5 ($50.00/1M tokens) is 8.3x more expensive than GPT-5.6 Luna ($6.00/1M tokens).

In conclusion, Claude Fable 5 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 Fable 5
Input tokens$10.00
Output tokens$50.00
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 Fable 5's 1,000,000 tokens. Both models can generate responses up to 128,000 tokens.

Anthropic
Claude Fable 5
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 Fable 5 and GPT-5.6 Luna support multimodal inputs.

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

Claude Fable 5

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 Fable 5

Proprietary

Closed source

GPT-5.6 Luna

Proprietary

Closed source

Release Timeline

When each model was launched

Claude Fable 5 was released on 2026-06-09, while GPT-5.6 Luna was released on 2026-07-09.

GPT-5.6 Luna is 1 month newer than Claude Fable 5.

Claude Fable 5

Jun 9, 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 Fable 5'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 Fable 5's cutoff date.

Claude Fable 5

—

GPT-5.6 Luna

Feb 2026

Provider Availability

Claude Fable 5 is available from Anthropic. GPT-5.6 Luna is available from OpenAI.

Claude Fable 5

anthropic logo
Anthropic
Input Price:Input: $10.00/1MOutput Price:Output: $50.00/1M

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 AutomationBench score (17.4% vs 14.9%)
Higher ExploitBench score (78.0% vs 33.2%)
Higher GDP.pdf score (29.8% vs 22.7%)
Higher GDPval-AA score (60.5% vs 53.1%)
Higher HealthBench Professional score (66.0% vs 55.7%)
Higher SWE-Bench Pro score (80.0% vs 62.7%)
OpenAI
Larger context window (1,050,000 tokens)
Less expensive input tokens
Less expensive output tokens
Higher Terminal-Bench 2.1 score (84.7% vs 84.3%)

Detailed Comparison

Interactive Arena

Judge for yourself.

Run your own prompts against Claude Fable 5 and GPT-5.6 Luna side-by-side, then vote on the output you prefer.

Claude Fable 5
✓ Preferred
GPT-5.6 Luna
Open in Playground
AI Model Comparison Table
Feature
Anthropic
Claude Fable 5
OpenAI
GPT-5.6 Luna

FAQ

Common questions about Claude Fable 5 vs GPT-5.6 Luna.

Which is better, Claude Fable 5 or GPT-5.6 Luna?

Claude Fable 5 significantly outperforms across most benchmarks. Claude Fable 5 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 Fable 5 compare to GPT-5.6 Luna in benchmarks?

Claude Fable 5 scores SWE-Bench Verified: 95.0%, FrontierSWE: 90.0%, OSWorld-Verified: 85.0%, Terminal-Bench 2.1: 84.3%, SWE-Bench Pro: 80.0%. 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 Fable 5 cheaper than GPT-5.6 Luna?

GPT-5.6 Luna is 10.0x cheaper for input tokens. Claude Fable 5 costs $10.00/M input and $50.00/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 Fable 5 and GPT-5.6 Luna?

Claude Fable 5 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 Fable 5 and GPT-5.6 Luna?

Key differences include context window (1.0M vs 1.1M), input pricing ($10.00 vs $1.00/M). See the full comparison above for benchmark-by-benchmark results.

Who makes Claude Fable 5 and GPT-5.6 Luna?

Claude Fable 5 is developed by Anthropic and GPT-5.6 Luna is developed by OpenAI.

Related comparisons