Claude Fable 5.1
Anthropicfamily · Claudeplatform.claude.com/docs/en/models/fable-5-1/ove
For demanding reasoning and long-horizon agentic work
Updated 4 h ago · first seen 11 Sept 2026
model_01M293V7EK3CVA2J99BHKR8PHG
Overview
Identity
- Canonical model
- Yesidentity confidence: mediumOne row per real model release. Artifacts (checkpoints, quantisations, conversions) and folded evaluation variants point here.
- Official checkpoints
- None recorded — closed weightsofficial_checkpoints = hf_repo identifiers carried by the model itself; artifacts are separate entities pointing here through canonical_id.
- Artifacts
- None recordedSeparate entities (checkpoint · quantization · conversion · packaging) pointing to this model through canonical_id.
- Provider deployments
- 2
- API aliases
- anthropic/claude-fable-5.1claude-fable-5-1claude-fable-5-1-highclaude-fable-5-1-lowclaude-fable-5-1-mediumclaude-fable-5-1-xhighIdentifiers under which providers and evaluators refer to this model.
- Folded evaluation variants
- 5Effort / thinking variants (…-high, …-non-reasoning) are result configurations of this model, not separate models. Their old URLs redirect here.
Openness
Closed / proprietary— weights not available; 7 dimensions unknown.
Weights are not available; the model is reachable only through an API or a product.
Weights
No
Inference code
—
Training code
—
Training data
—
Dataset
—
Commercial use
—
Redistribution
—
Derivatives
—
dimensions marked null are unknown, not false
Key facts
- Release date
Source:Claude Developer Platform docsT1observed 14 h agohigh
- Status
Source:Claude Developer Platform docsT1observed 14 h agohigh
- Knowledge cutoff
Source:Claude Developer Platform docsT1observed 14 h agohigh
- Retirement date
Source:Claude Developer Platform docsT1observed 14 h agohigh
- Official page
Source:Claude Developer Platform docsT1observed 14 h agohigh
- API model id
Source:Claude Developer Platform docsT1observed 14 h agohigh
- Openrouter id
Source:OpenRouter public model & pricing listingT2observed 14 h agomedium
Architecture
- Tokenizer
Source:OpenRouter public model & pricing listingT2observed 14 h agomedium
- Training data cutoff
Source:Claude Developer Platform docsT1observed 14 h agohigh
Capabilities
Modalities
- Modalities
- textimage
- Input
- textimage
- Output
- text
Capabilities
Tool calling
Yes
Claude Developer Platform docs · T1
Structured output
Yes
OpenRouter public model & pricing listing · T2
Reasoning
Yes
OpenRouter public model & pricing listing · T2
Vision
Yes
Claude Developer Platform docs · T1
Audio
Unavailable
Fine-tuning available
Unavailable
- Context window
Source:Claude Developer Platform docsT1observed 14 h agohigh
- Max output
Source:Claude Developer Platform docsT1observed 14 h agohigh
- Knowledge cutoff
Source:Claude Developer Platform docsT1observed 14 h agohigh
- Tokenizer
Source:OpenRouter public model & pricing listingT2observed 14 h agomedium
Benchmarks68
Compare with another model →Comparable same task and conditions · Partially comparable same task, conditions differ (effort, temperature, judge) · Not comparable different variant or metric
Current rows only, grouped by benchmark → canonical metric → comparability group (task configuration). Effort variants folded into this model appear as rows of the same group. 68 current rows in total. “vs leader” compares with the current leader of the benchmark's primary group only; other groups are not directly comparable. Comparability rules →
Providers & Pricing5
All offers in the price terminal →USD per 1M tokens as published by each provider; native units (per-request fees, flex/priority tiers) are kept verbatim. Rows are append-only — every price change is kept in the history below. Cost of a workload →
Price history
Output price · USD / 1M tokens 2 providers
- Anthropic API
- OpenRouter
- OpenRouter$50 → $2512 Sept 2026
- OpenRouterfirst observed $5012 Sept 2026
- Anthropic API$50 → $2511 Sept 2026
- Anthropic APIfirst observed $5011 Sept 2026
Input price · USD / 1M tokens 2 providers
- Anthropic API
- OpenRouter
- OpenRouter$10 → $512 Sept 2026
- OpenRouterfirst observed $1012 Sept 2026
- Anthropic API$10 → $511 Sept 2026
- Anthropic APIfirst observed $1011 Sept 2026
Versions & Artifacts0
Version history
Context windowfirst observation only
11 Sept 2026current
Knowledge cutofffirst observation only
11 Sept 2026current
Max outputfirst observation only
11 Sept 2026current
Opennessfirst observation only
11 Sept 2026current
Statusfirst observation only
11 Sept 2026current
Each hop is a claim: click a value for its source, tier and observation time. Nothing is overwritten — a new observation closes the previous claim.
Artifacts 0
No artifact (checkpoint, quantisation, conversion or packaging) points to this model yet.
Timeline30
Full timeline →OpenRouter lists Claude Fable 5.1 at $5 in / $25 out per 1M tokens
openrouterOpenRouter lists Claude Fable 5.1 at $10 in / $50 out per 1M tokens
openrouterClaude Fable 5.1 scores 85.02% on Terminal-Bench
artificial_analysisClaude Fable 5.1 scores 40.4% on Terminal-Bench
artificial_analysisClaude Fable 5.1 scores 56.71% on SciCode
artificial_analysisClaude Fable 5.1 scores 48.89% on Humanity's Last Exam
artificial_analysisClaude Fable 5.1 scores 88.08% on GPQA Diamond
artificial_analysisClaude Fable 5.1 scores 47.04 on Artificial Analysis Intelligence Index
artificial_analysisClaude Fable 5.1 scores 88.01% on Terminal-Bench
artificial_analysisClaude Fable 5.1 scores 44.95% on Terminal-Bench
artificial_analysisClaude Fable 5.1 scores 56.37% on SciCode
artificial_analysisClaude Fable 5.1 scores 53.8% on Humanity's Last Exam
artificial_analysisClaude Fable 5.1 scores 88.59% on GPQA Diamond
artificial_analysisClaude Fable 5.1 scores 49.06 on Artificial Analysis Intelligence Index
artificial_analysisClaude Fable 5.1 scores 91.39% on Terminal-Bench
artificial_analysisClaude Fable 5.1 scores 52.02% on Terminal-Bench
artificial_analysisClaude Fable 5.1 scores 63.08% on SciCode
artificial_analysisClaude Fable 5.1 scores 59.13% on Humanity's Last Exam
artificial_analysisClaude Fable 5.1 scores 93.74% on GPQA Diamond
artificial_analysisClaude Fable 5.1 scores 53.37 on Artificial Analysis Intelligence Index
artificial_analysisClaude Fable 5.1 scores 91.01% on Terminal-Bench
artificial_analysisClaude Fable 5.1 scores 55.05% on Terminal-Bench
artificial_analysisClaude Fable 5.1 scores 60.88% on SciCode
artificial_analysisClaude Fable 5.1 scores 58.71% on Humanity's Last Exam
artificial_analysisClaude Fable 5.1 scores 93.43% on GPQA Diamond
artificial_analysisClaude Fable 5.1 scores 53.18 on Artificial Analysis Intelligence Index
artificial_analysisClaude Fable 5.1 scores 89.89% on Terminal-Bench
artificial_analysisClaude Fable 5.1 scores 52.02% on Terminal-Bench
artificial_analysisClaude Fable 5.1 scores 58.68% on SciCode
artificial_analysisClaude Fable 5.1 scores 55.93% on Humanity's Last Exam
artificial_analysis
Change history63
Viewing AI Atlas as of 1 Sept 2026 — attributes exactly as the atlas knew them on that day; later corrections are not shown.
Back to today →Claude Fable 5.1 was not yet in AI Atlas on 1 Sept 2026
Familyfamily1
Release daterelease_date1
Statusstatus1
Opennessopenness5
Context windowcontext_length5
Max outputmax_output_tokens1
Knowledge cutoffknowledge_cutoff1
Training data cutofftraining_data_cutoff1
Modalitiesmodalities6conflicting claims
Input modalitiesmodalities_input6conflicting claims
Output modalitiesmodalities_output1
Tokenizertokenizer1
API model idapi_model_id1
API aliasapi_alias1
Retirement dateretirement_date1
Retirement tentativeretirement_tentative1
Official pageofficial_url1
Aa context windowaa_context_window1
Aa opennessaa_openness1
Bedrock model idbedrock_model_id1
Claude aws model idclaude_aws_model_id1
Default effortdefault_effort1
Descriptiondescription1
File inputfile_input1
Foundry model idfoundry_model_id1
Latency tierlatency_tier1
Aa median output tokens per secondmetric.aa_median_output_tokens_per_second5
Openrouter idopenrouter_id1
Openrouter listed atopenrouter_listed_at1
Reasoningreasoning5
Structured outputstructured_output1
Supported parameterssupported_parameters1
Thinkingthinking1
Tool callingtool_calling1
Vertex model idvertex_model_id1
Visionvision1
Weights availableweights_available1
Claims are temporal and append-only: a new observation closes the previous claim (valid_to) instead of overwriting it. Conflicting claims from different sources are kept side by side and flagged — never averaged. Methodology →
Provenance
Attributed facts
37
Source tiers
T1T226 / 11
Freshest observation
4 h ago
Conflicts
10 flagged
Source documents 6
Tier 1 = official/primary, 2 = quality secondary, 3 = community, 4 = unverified. Every snapshot is archived; see all sources and the methodology.
Data quality (76/100) measures how well AI Atlas knows this entity — completeness, primary-source ratio, freshness, conflicts — never how good the model is. Methodology →