Claude Fable 5.1 (Adaptive Reasoning, Max Effort, Default Fallback) vs GPT-6 Astra (max)Benchmark Comparison 2026

Objective comparison based on public benchmarks updated weekly: Intelligence Index, Chatbot Arena ELO, pricing and speed.

Overall winner (2026)

Claude Fable 5.1 (Adaptive Reasoning, Max Effort, Default Fallback)

4 of 5 criteria won

Anthropic

Claude Fable 5.1 (Adaptive Reasoning, Max Effort, Default Fallback)

Winner

ELO Arena

1501

Intelligence Index

53.4

Coding Index

81.6

4 criteria won

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OpenAI

GPT-6 Astra (max)

ELO Arena

1476

Intelligence Index

52.7

Coding Index

76.9

1 criterion won

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Detailed Comparison

Critério	Claude Fable 5.1 (Adaptive Reasoning, Max Effort, Default Fallback)	GPT-6 Astra (max)
Chatbot Arena ELO	1501 ✓	1476
Intelligence Index (AA)	53.4 ✓	52.7
Coding Index (AA)	81.6 ✓	76.9
Input price ($/1M tok)	$10.00	$10.00
Output price ($/1M tok)	$50.00	$50.00
Context window	1.0M tokens	1.1M tokens ✓
Speed (tokens/s)	68 tok/s ✓	52 tok/s

✓ = winner in this criterion • Source: Artificial Analysis, LMArena, official APIs • Updated weekly

Technical Specifications

Claude Fable 5.1 (Adaptive Reasoning, Max Effort, Default Fallback)

Company: Anthropic
Context window: 1.0M tokens
Input ($/1M tok): $10.00
Output ($/1M tok): $50.00
Speed: 68 tok/s
Release: Sep 2026
Multimodal: No
Open Source: No

GPT-6 Astra (max)

Company: OpenAI
Context window: 1.1M tokens
Input ($/1M tok): $10.00
Output ($/1M tok): $50.00
Speed: 52 tok/s
Release: Sep 2026
Multimodal: No
Open Source: No

When to use Claude Fable 5.1 (Adaptive Reasoning, Max Effort, Default Fallback) vs GPT-6 Astra (max)?

Choosing between Claude Fable 5.1 (Adaptive Reasoning, Max Effort, Default Fallback) and GPT-6 Astra (max) depends on your use case, budget and technical requirements. Below, a practical guide based on benchmark data and each model's specifications.

Use Claude Fable 5.1 (Adaptive Reasoning, Max Effort, Default Fallback) when:

Anthropic · Text

→Critical tasks where maximum quality justifies premium cost — ideal for one-off high-value decisions
→Long document analysis — 1.0M tokens context window allows processing books, legal databases and extensive logs
→API integration in SaaS applications — direct API access with documented SLA

View full Claude Fable 5.1 (Adaptive Reasoning, Max Effort, Default Fallback) profile →

Use GPT-6 Astra (max) when:

OpenAI · Text

→Critical tasks where maximum quality justifies premium cost — ideal for one-off high-value decisions
→Long document analysis — 1.1M tokens context window allows processing books, legal databases and extensive logs
→AI agents with tool calling — workflow automation, external API integration and data pipelines
→API integration in SaaS applications — direct API access with documented SLA

View full GPT-6 Astra (max) profile →

SWEN Verdict: Claude Fable 5.1 (Adaptive Reasoning, Max Effort, Default Fallback) wins in more objective criteria in this comparison (4 vs 1). For most use cases, Claude Fable 5.1 (Adaptive Reasoning, Max Effort, Default Fallback) offers better aggregate performance — but GPT-6 Astra (max) may be preferable if your project prioritizes critical tasks where maximum quality justifies premium cost.

Frequently Asked Questions

Claude Fable 5.1 (Adaptive Reasoning, Max Effort, Default Fallback) or GPT-6 Astra (max): which is better?

Claude Fable 5.1 (Adaptive Reasoning, Max Effort, Default Fallback) wins in 4 of 5 criteria analyzed. Check the full table to choose based on your use case.

Where does this benchmark data come from?

Data is aggregated from Artificial Analysis (Intelligence Index, Coding Index) and Chatbot Arena/LMArena (ELO). Pricing and specs come from official APIs. Updated weekly.

What is the Intelligence Index?

The Intelligence Index is an aggregate score from Artificial Analysis that combines multiple academic benchmarks (MMLU, GPQA, LiveBench, etc.) into a single rating. The higher the score, the more capable the model is at reasoning tasks.

Is Claude Fable 5.1 (Adaptive Reasoning, Max Effort, Default Fallback) cheaper than GPT-6 Astra (max)?

Claude Fable 5.1 (Adaptive Reasoning, Max Effort, Default Fallback) and GPT-6 Astra (max) have the same input price: $10/1M tokens. The actual cost difference depends on output pricing and your application's input/output ratio.

Claude Fable 5.1 (Adaptive Reasoning, Max Effort, Default Fallback) or GPT-6 Astra (max): which has a larger context window?

GPT-6 Astra (max) has the larger context window: 1.1M tokens vs 1.0M tokens. For long document analysis, extensive transcripts or full codebases, the larger context window is a decisive criterion.

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