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Proprietary release

Released September 2026

Claude Fable 5.1: Release Intelligence, Performance & Price

Available providers

The Claude Fable 5.1 release offers 5 models, each with different intelligence, performance, and pricing characteristics. Below is a comparison of the key metrics across the 5 models.

  • For intelligence, the top model of Claude Fable 5.1 is Claude Fable 5.1 (Adaptive Reasoning, Max Effort, Default Fallback) at 53.
  • For output speed, the fastest model is Claude Fable 5.1 (Adaptive Reasoning, Max Effort, Default Fallback) at 67 t/s.
  • For latency, Claude Fable 5.1 (Adaptive Reasoning, Low Effort, Default Fallback) at 6.78s offers the lowest time to first answer token.
  • For pricing, Claude Fable 5.1 (Adaptive Reasoning, Low Effort, Default Fallback) at $2.37 offers the lowest cost per task. Prices vary up to 3.2x across models.

ReasoningYes

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 window1M
~1500 A4 pages of size 12 Arial font

Intelligence

Artificial Analysis Intelligence Index

Artificial Analysis Intelligence Index v4.3 incorporates 10 evaluations: AA-Briefcase, GDPval-AA v2, AutomationBench-AA, Terminal-Bench v4.0, SciCode, Humanity's Last Exam, GDP.pdf, CritPt, AA-Omniscience, AA-LCR v1.1

Artificial Analysis Intelligence Index v4.3 includes: AA-Briefcase, GDPval-AA v2, AutomationBench-AA, Terminal-Bench v4.0, SciCode, Humanity's Last Exam, GDP.pdf, CritPt, AA-Omniscience, AA-LCR v1.1. See Intelligence Index methodology for further details, including a breakdown of each evaluation and how we run them.

Intelligence Index vs. Cost per Intelligence Index Task

Artificial Analysis Intelligence Index · Weighted average cost (USD) per Artificial Analysis Intelligence Index task
Most attractive quadrant
Claude Fable 5.1
Pareto line

Weighted average cost per Intelligence Index task. Each evaluation’s cost is calculated from input, cache hit, cache write, reasoning, and answer token prices, divided by task count, and weighted by its Intelligence Index weight.

Artificial Analysis Intelligence Index v4.3 includes: AA-Briefcase, GDPval-AA v2, AutomationBench-AA, Terminal-Bench v4.0, SciCode, Humanity's Last Exam, GDP.pdf, CritPt, AA-Omniscience, AA-LCR v1.1. See Intelligence Index methodology for further details, including a breakdown of each evaluation and how we run them.

Cost

Cost per Intelligence Index Task

Weighted average cost (USD) per Artificial Analysis Intelligence Index task, segmented by token type. Lower is better

Weighted average cost per Intelligence Index task. Each evaluation’s cost is calculated from input, cache hit, cache write, reasoning, and answer token prices, divided by task count, and weighted by its Intelligence Index weight.

Speed & Latency

Output Speed

Output tokens per second · Higher is better

Tokens per second received while the model is generating tokens (ie. after first chunk has been received from the API for models which support streaming).

Figures represent performance of the model's first-party API (e.g. OpenAI for o1) or the median across providers where a first-party API is not available (e.g. Meta's Llama models).

Capability Scores

Capability Indices

Measures the performance of models on specific capabilities and industries
Finance & Accounting Index

Incorporates 5 evaluations: AA-Omniscience, GDPval-AA v2, Humanity's Last Exam, 𝜏³-Banking, AA-LCR v1.1 · Higher is better

Strategy & Ops Index

Incorporates 4 evaluations: AA-Omniscience, GDPval-AA v2, 𝜏³-Banking, AA-LCR v1.1 · Higher is better

Legal Index

Incorporates 5 evaluations: AA-Omniscience, GDPval-AA v2, AA-LCR v1.1, 𝜏³-Banking, Humanity's Last Exam · Higher is better

Healthcare & Medical Index

Incorporates 5 evaluations: AA-Omniscience, GDPval-AA v2, MLCR-AA, Humanity's Last Exam, 𝜏³-Banking · Higher is better

Engineering Index

Incorporates 6 evaluations: AA-Omniscience, Humanity's Last Exam, GPQA Diamond, CritPt, GDPval-AA v2, Terminal-Bench v2.1 · Higher is better

Economics Index

Incorporates 4 evaluations: AA-Omniscience, Humanity's Last Exam, GDPval-AA v2, AA-LCR v1.1 · Higher is better

More from Anthropic

Further details

Weights
Provider Benchmarks
Claude Fable 5.1 (Adaptive Reasoning, Max Effort, Default Fallback)
Anthropic logoAnthropic
53
-
1M
$7.2
67
Not available
Anthropic
Claude Fable 5.1 (Adaptive Reasoning, Xhigh Effort, Default Fallback)
Anthropic logoAnthropic
53
-
1M
$7.2
58
Not available
Anthropic
Claude Fable 5.1 (Adaptive Reasoning, High Effort, Default Fallback)
Anthropic logoAnthropic
51
-
1M
$7.2
51
Not available
Anthropic
Claude Fable 5.1 (Adaptive Reasoning, Medium Effort, Default Fallback)
Anthropic logoAnthropic
49
-
1M
$7.2
51
Not available
Anthropic
Claude Fable 5.1 (Adaptive Reasoning, Low Effort, Default Fallback)
Anthropic logoAnthropic
47
-
1M
$7.2
47
Not available
Anthropic