Fable 5.1 is the new frontier on artificialanalysis

Anthropic's Claude Fable 5.1 (Adaptive Reasoning, Max Effort, Default Fallback) scores 66 on the Artificial Analysis Intelligence Index, well above the median of 36 for comparable models, according to artificialanalysis.ai. The model, released September 1, 2026, costs $10.00 per 1M input tokens and $50.00 per 1M output tokens, with a total evaluation cost of $8,523.16. It supports text and image input, outputs text, and has a 1M token context window.

Claude Fable 5.1 Adaptive Reasoning, Max Effort, Default Fallback Intelligence, Performance & Price Analysis Model summary Speed Claude Fable 5.1 Adaptive Reasoning, Max Effort, Default Fallback is amongst the leading models in intelligence, but particularly expensive when comparing to other models of similar price. The model supports text and image input, outputs text, and has a 1M tokens context window. Claude Fable 5.1 Adaptive Reasoning, Max Effort, Default Fallback scores 66 on the Artificial Analysis Intelligence Index, placing it well above average among comparable models median: 36 . When evaluating the Intelligence Index, it generated 140M tokens, which is very verbose in comparison to the median of 71M. Pricing for Claude Fable 5.1 Adaptive Reasoning, Max Effort, Default Fallback is $10.00 per 1M input tokens expensive, median: $2.00 and $50.00 per 1M output tokens expensive, median: $10.00 . In total, it cost $8523.16 to evaluate Claude Fable 5.1 Adaptive Reasoning, Max Effort, Default Fallback on the Intelligence Index. | Reasoning | Yes This page shows the reasoning version of this model. A non-reasoning variant may also exist. | |---|---| | Input modality | Supports: text and image | | Output modality | Supports: text | | Context window | 1M ~1500 A4 pages of size 12 Arial font | Metrics are compared against models of the same class: - Non-reasoning models → compared only with other non-reasoning models - Reasoning models → compared across both reasoning and non-reasoning - Open weights models → compared only with other open weights models of the same size class: - Tiny: ≤4B parameters - Small: 4B–40B parameters - Medium: 40B–150B parameters - Large: 150B parameters - Proprietary models → compared across proprietary and open weights models of the same price range, using a blended 3:1 input/output price ratio: - <$0.15 per 1M tokens - $0.15–$1 per 1M tokens - $1 per 1M tokens Highlights Speed Intelligence Artificial Analysis Intelligence Index /evaluations/artificial-analysis-intelligence-index Artificial Analysis Intelligence Index by Open Weights / Proprietary Intelligence Evaluations Agentic real-world work tasks, Elo-500 /2000 Agentic tool use Agentic coding & terminal use Coding Reasoning & knowledge Scientific reasoning Physics reasoning Knowledge 1 - hallucination rate Long context reasoning Agentic knowledge work, Elo Agentic SaaS workflows Legal agentic work, criterion pass rate Agentic business operations Quantitative analysis on spreadsheets & documents Instruction following Long-horizon agentic tasks Kubernetes incident root-cause analysis Visual reasoning AA-Briefcase AA-Briefcase Elo AA-Omniscience AA-Omniscience Index Intelligence Index Comparisons Intelligence Index vs. Cost per Intelligence Index Task Token Use Output Tokens per Intelligence Index Task Cost Cost per Intelligence Index Task Cost to Run Artificial Analysis Intelligence Index Pricing: Cache Hit, Input, and Output Context Window Context Window Frequently Asked Questions Common questions about Claude Fable 5.1 Adaptive Reasoning, Max Effort, Default Fallback Claude Fable 5.1 Adaptive Reasoning, Max Effort, Default Fallback was released on September 1, 2026. Claude Fable 5.1 Adaptive Reasoning, Max Effort, Default Fallback was created by Anthropic. Claude Fable 5.1 Adaptive Reasoning, Max Effort, Default Fallback scores 66 on the Artificial Analysis Intelligence Index, placing it well above average among other reasoning models in a similar price tier median: 36 . Claude Fable 5.1 Adaptive Reasoning, Max Effort, Default Fallback costs $10.00 per 1M input tokens at the higher end, median: $2.00 and $50.00 per 1M output tokens at the higher end, median: $10.00 , based on Anthropic's API. Claude Fable 5.1 Adaptive Reasoning, Max Effort, Default Fallback costs $10.00 per 1M input tokens and $50.00 per 1M output tokens based on Anthropic's API . For a blended rate 7:2:1 cache hit/input/output ratio , this is $7.17 per 1M tokens. Pricing may vary by provider. Compare provider pricing /models/claude-fable-5-1/providers When evaluated on the Intelligence Index, Claude Fable 5.1 Adaptive Reasoning, Max Effort, Default Fallback generated 140M output tokens, which is at the higher end compared to other reasoning models in a similar price tier median: 71M . Yes, Claude Fable 5.1 Adaptive Reasoning, Max Effort, Default Fallback is a reasoning model. It uses extended thinking or chain-of-thought reasoning to work through complex problems before providing an answer. Claude Fable 5.1 Adaptive Reasoning, Max Effort, Default Fallback supports text and image input. Claude Fable 5.1 Adaptive Reasoning, Max Effort, Default Fallback supports text output. Yes, Claude Fable 5.1 Adaptive Reasoning, Max Effort, Default Fallback supports image input and can analyze, describe, and answer questions about images. Yes, Claude Fable 5.1 Adaptive Reasoning, Max Effort, Default Fallback is multimodal. It can process text and image input and generate text output. Claude Fable 5.1 Adaptive Reasoning, Max Effort, Default Fallback has a context window of 1.0M tokens. This determines how much text and conversation history the model can process in a single request. No, Claude Fable 5.1 Adaptive Reasoning, Max Effort, Default Fallback is proprietary. The model weights are not publicly available. Claude Fable 5.1 Adaptive Reasoning, Max Effort, Default Fallback is a proprietary model and Anthropic has not disclosed the model size or parameter count. Claude Fable 5.1 Adaptive Reasoning, Max Effort, Default Fallback achieves a score of 66 on the Artificial Analysis Intelligence Index. This composite benchmark evaluates models across reasoning, knowledge, mathematics, and coding. Yes, Claude Fable 5.1 Adaptive Reasoning, Max Effort, Default Fallback is available via API through 1 provider. Compare API providers /models/claude-fable-5-1/providers Claude Fable 5.1 Adaptive Reasoning, Max Effort, Default Fallback is available through 1 API provider. Compare providers /models/claude-fable-5-1/providers