Claude Fable 5.1

anthropic/claude-fable-5.1-20260831

Claude Fable 5.1 is a text, image, and file input model that generates text outputs. It supports a 1,000,000 token context window, tool use, and reasoning.

  • tool use
  • structured outputs
  • reasoning

At a glance

provideranthropic
releasedAug 29, 2026
context1M
input / M$10

Specifications

What the API gives you

Context window
1M tokens
Max output
128K tokens
Input price
$10 / 1M tokens
Output price
$50 / 1M tokens
Cache read
$0.25 / 1M tokens
Modalities
text, image, file → text
Knowledge cutoff
—
Released
Aug 29, 2026

Measured evidence

Public benchmark record

Design Arena Coding
1336 Elo2026-10-20
Design Arena Full-stack Agent
1326 Elo2026-10-14
Design Arena UI
1340 Elo2026-10-20
Design Arena Web-app Agent
1318 Elo2026-10-20
Design Arena Website
1314 Elo2026-10-20
FrontierMath Tiers 1-3 (Epoch AI)‡
90.2% ± 1.82026-09-01max effort, evaluated 2026-09-01
LiveBench Agentic Coding
66.1%2026-10-18
LiveBench Coding
86.4%2026-10-18
LiveBench Data Analysis
80.3%2026-10-18
LiveBench Instruction Following
73.0%2026-10-18
LiveBench Language
89.5%2026-10-18
LiveBench Math
97.0%2026-10-18
LiveBench Reasoning
91.7%2026-10-18
LMArena Agent‡
14.32026-10-19max effort
LMArena Agent Bash Recovery‡
11.62026-10-08max effort
LMArena Agent Steerability‡
14.82026-10-19max effort
LMArena Agent Task Outcome‡
15.12026-10-19max effort
LMArena Agent Tool Hallucination‡
0.72026-10-19max effort
LMArena Creative Writing‡
1508 Elo2026-10-15max effort
LMArena Instruction Following‡
1517 Elo2026-10-15max effort
LMArena Long Query‡
1523 Elo2026-10-15max effort
LMArena Math‡
1528 Elo2026-10-15max effort
LMArena Search Factuality
1222 Elo2026-10-13
LMArena Text‡
1502 Elo2026-10-15max effort
LMArena Text Factuality‡
1498 Elo2026-10-15max effort
LMArena Vision‡
1288 Elo2026-10-19max effort
LMArena Vision Diagrams‡
1323 Elo2026-10-19max effort
LMArena Vision OCR‡
1303 Elo2026-10-19max effort
LMArena WebDev‡
1743 Elo2026-10-19max effort
LMArena WebDev Image-to-Web‡
1722 Elo2026-10-19max effort
OTIS Mock AIME (Epoch AI)‡
100% ± 02026-09-01max effort, evaluated 2026-09-01
SimpleQA Verified (Epoch AI)‡
70.8% ± 1.42026-09-01max effort, evaluated 2026-09-01
Terminal-Bench (4.0)‡
57.9%2026-10-20Claude Code, max effort, evaluated 2026-09-03

LMArena data licensed CC-BY-4.0. Aider (Apache-2.0) and SWE-bench (MIT) are open. Design Arena uses blind human preference. ‡ Submitted scaffold plus model result. Compare the harness and effort settings, not only the model name.

Task evidence

How broad is the support?

Each status is exact to this model version and the selected task. Official release claims remain provisional.

  • Best LLM for Competition MathEstablished evidence

    100% of intended weighted task evidence across 4 independent sources. 6 of 6 configured evaluation feeds currently have results.

  • Best LLM for Business WritingEstablished evidence

    100% of intended weighted task evidence across 2 independent sources. 4 of 4 configured evaluation feeds currently have results.

  • Best LLM for Marketing CopyEstablished evidence

    100% of intended weighted task evidence across 2 independent sources. 4 of 4 configured evaluation feeds currently have results.

  • Best LLM for Chat & RoleplayEstablished evidence

    100% of intended weighted task evidence across 2 independent sources. 4 of 4 configured evaluation feeds currently have results.

  • Best LLM for Creative WritingEstablished evidence

    100% of intended weighted task evidence across 2 independent sources. 4 of 4 configured evaluation feeds currently have results.

  • Best LLM for Frontend & UIEstablished evidence

    100% of intended weighted task evidence across 3 independent sources. 6 of 6 configured evaluation feeds currently have results.

Show all 45 tasks
  • Best LLM for WritingEstablished evidence

    100% of intended weighted task evidence across 2 independent sources. 4 of 4 configured evaluation feeds currently have results.

  • Best LLM for Roleplay & CharacterEstablished evidence

    100% of intended weighted task evidence across 2 independent sources. 4 of 4 configured evaluation feeds currently have results.

  • Best LLM for a General AssistantEstablished evidence

    100% of intended weighted task evidence across 3 independent sources. 6 of 6 configured evaluation feeds currently have results.

  • Best LLM for Math & ReasoningEstablished evidence

    88% of intended weighted task evidence across 4 independent sources. 7 of 7 configured evaluation feeds currently have results.

  • Best LLM for Logic & Problem SolvingEstablished evidence

    82% of intended weighted task evidence across 2 independent sources. 5 of 5 configured evaluation feeds currently have results.

  • Best LLM for Agentic CodingEstablished evidence

    80% of intended weighted task evidence across 4 independent sources. 7 of 7 configured evaluation feeds currently have results.

  • Best LLM for Code CompletionEstablished evidence

    79% of intended weighted task evidence across 2 independent sources. 3 of 3 configured evaluation feeds currently have results.

  • Best LLM for Autonomous AgentsEstablished evidence

    67% of intended weighted task evidence across 3 independent sources. 6 of 6 configured evaluation feeds currently have results.

  • Best LLM for CodingEstablished evidence

    64% of intended weighted task evidence across 4 independent sources. 7 of 7 configured evaluation feeds currently have results.

  • Best Open-Weight LLM for Self-HostingEstablished evidence

    64% of intended weighted task evidence across 2 independent sources. 2 of 3 configured evaluation feeds currently have results.

  • Best LLM for Image UnderstandingEstablished evidence

    61% of intended weighted task evidence across 2 independent sources. 2 of 3 configured evaluation feeds currently have results.

  • Best LLM for Document SummarizationEstablished evidence

    60% of intended weighted task evidence across 2 independent sources. 5 of 6 configured evaluation feeds currently have results.

  • Best LLM for SummarizationEstablished evidence

    60% of intended weighted task evidence across 2 independent sources. 5 of 6 configured evaluation feeds currently have results.

  • Best LLM for Fast SummariesEstablished evidence

    58% of intended weighted task evidence across 2 independent sources. 2 of 3 configured evaluation feeds currently have results.

  • Best Value LLMEstablished evidence

    58% of intended weighted task evidence across 2 independent sources. 2 of 3 configured evaluation feeds currently have results.

  • Best LLM for AI AgentsEstablished evidence

    50% of intended weighted task evidence across 3 independent sources. 9 of 9 configured evaluation feeds currently have results.

  • Best LLM for Literary TranslationEstablished evidence

    50% of intended weighted task evidence across 2 independent sources. 3 of 4 configured evaluation feeds currently have results.

  • Best LLM for Everyday TranslationEstablished evidence

    50% of intended weighted task evidence across 2 independent sources. 3 of 4 configured evaluation feeds currently have results.

  • Best LLM for TranslationEstablished evidence

    50% of intended weighted task evidence across 2 independent sources. 3 of 4 configured evaluation feeds currently have results.

  • Best LLM for Grounded RAGEstablished evidence

    48% of intended weighted task evidence across 2 independent sources. 5 of 7 configured evaluation feeds currently have results.

  • Best LLM for Hermes AgentEstablished evidence

    48% of intended weighted task evidence across 2 independent sources. 4 of 4 configured evaluation feeds currently have results.

  • Best LLM for OpenHandsEstablished evidence

    48% of intended weighted task evidence across 2 independent sources. 4 of 4 configured evaluation feeds currently have results.

  • Best LLM for GooseEstablished evidence

    48% of intended weighted task evidence across 2 independent sources. 4 of 4 configured evaluation feeds currently have results.

  • Best LLM for OpenClawEstablished evidence

    48% of intended weighted task evidence across 2 independent sources. 4 of 4 configured evaluation feeds currently have results.

  • Best Local LLM for CodingEstablished evidence

    47% of intended weighted task evidence across 2 independent sources. 4 of 4 configured evaluation feeds currently have results.

  • Best Cheap LLM for High VolumeEstablished evidence

    40% of intended weighted task evidence across 2 independent sources. 2 of 3 configured evaluation feeds currently have results.

  • Cheapest Capable LLMEstablished evidence

    40% of intended weighted task evidence across 2 independent sources. 2 of 3 configured evaluation feeds currently have results.

  • Best LLM for JSON & Schema OutputEstablished evidence

    35% of intended weighted task evidence across 2 independent sources. 3 of 4 configured evaluation feeds currently have results.

  • Best LLM for Structured Data ExtractionEstablished evidence

    35% of intended weighted task evidence across 2 independent sources. 3 of 4 configured evaluation feeds currently have results.

  • Best LLM for Debugging & Code ReviewEstablished evidence

    33% of intended weighted task evidence across 2 independent sources. 5 of 5 configured evaluation feeds currently have results.

  • Best LLM for OCR & DocumentsProvisional evidence

    65% of intended weighted task evidence across 1 independent source; broader independent confirmation is still missing from Structured-output eval or VLMEvalKit tasks. 3 of 5 configured evaluation feeds currently have results.

  • Best LLM for Charts & DiagramsProvisional evidence

    65% of intended weighted task evidence across 1 independent source; broader independent confirmation is still missing from Structured-output eval or VLMEvalKit tasks. 3 of 5 configured evaluation feeds currently have results. Official release evidence is also tracked provisionally.

  • Best LLM for Vision & DocumentsProvisional evidence

    60% of intended weighted task evidence across 1 independent source; broader independent confirmation is still missing from Structured-output eval or VLMEvalKit tasks. 4 of 6 configured evaluation feeds currently have results.

  • Best LLM for Document ParsingProvisional evidence

    58% of intended weighted task evidence across 1 independent source; broader independent confirmation is still missing from Structured-output eval or VLMEvalKit tasks. 3 of 5 configured evaluation feeds currently have results. Official release evidence is also tracked provisionally.

  • Best LLM for RAG & Long ContextProvisional evidence

    50% of intended weighted task evidence across 1 independent source; broader independent confirmation is still missing from FACTS Grounding or LongBench v2. 5 of 6 configured evaluation feeds currently have results.

  • Best LLM for Massive ContextProvisional evidence

    47% of intended weighted task evidence across 1 independent source; broader independent confirmation is still missing from LongBench v2. 2 of 3 configured evaluation feeds currently have results.

  • Best LLM for Tool & Function CallingProvisional evidence

    46% of intended weighted task evidence across 1 independent source; broader independent confirmation is still missing from Berkeley Function Calling or Structured-output eval. 6 of 7 configured evaluation feeds currently have results. Official release evidence is also tracked provisionally.

  • Best LLM for High-Volume ExtractionProvisional evidence

    21% of intended weighted task evidence across 1 independent source; broader independent confirmation is still missing from Route reliability or Structured-output eval. 1 of 3 configured evaluation feeds currently have results.

  • Best LLM for Computer & Browser UseProvisional evidence

    17% of intended weighted task evidence across 1 independent source; broader independent confirmation is still missing from Berkeley Function Calling or OSWorld Verified. 3 of 3 configured evaluation feeds currently have results. Official release evidence is also tracked provisionally.

Official release evidence · provisional

What the launch material actually says

Verbatim claims from the model provider. These help on launch day but do not count as independent confirmation.

Recommendation coverage

Where this model appears

  1. #1Best LLM for Tool & Function Calling
  2. #1Best LLM for Competition Math
  3. #1Best LLM for Math & Reasoning
  4. #1Best LLM for Massive Context
  5. #2Best LLM for Agentic Coding
  6. #3Best LLM for Code Completion
  7. #3Best LLM for Literary Translation
  8. #3Best LLM for Charts & Diagrams
  9. #3Best LLM for Computer & Browser Use
  10. #3Best LLM for Everyday Translation
  11. #3Best LLM for Autonomous Agents
  12. #3Best LLM for Translation
  13. #3Best LLM for Coding
  14. #3Best LLM for a General Assistant
  15. #3Best LLM for Debugging & Code Review
  16. #3Best LLM for Logic & Problem Solving
  17. #3Best LLM for AI Agents
  18. #4Best LLM for Document Parsing
  19. #4Best LLM for Summarization
  20. #4Best LLM for Chat & Roleplay
  21. #4Best LLM for Vision & Documents
  22. #4Best LLM for Writing
  23. #4Best LLM for Document Summarization
  24. #4Best LLM for Frontend & UI
  25. #4Best LLM for Creative Writing
  26. #4Best LLM for Grounded RAG
  27. #4Best LLM for Roleplay & Character
  28. #5Best LLM for OpenHands
  29. #5Best LLM for OpenClaw
  30. #5Best LLM for Hermes Agent
  31. #5Best LLM for Business Writing
  32. #5Best LLM for Image Understanding
  33. #5Best LLM for Marketing Copy
  34. #5Best LLM for OCR & Documents
  35. #5Best LLM for Goose

Compare head to head

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