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Claude Fable 5.1 vs o3

Full profiles: Claude Fable 5.1 (Anthropic) and o3 (OpenAI): every benchmark, price and rank.

Updated · Data from 17 sources

As of 26 Oct 2026, Claude Fable 5.1 (max) leads on quality (70.5 vs 59.5 on the BenchLeader Index), but o3 costs 5.7× less, so it is the better buy unless you need the extra quality. Pick Claude Fable 5.1 for reasoning (77 vs 52); pick o3 for agents & tools (70 vs 61).

Claude Fable 5.1 benchmarks max Anthropic o3 benchmarks OpenAIOpen in the comparison tool

Which to pick for…

The pick's numbers come first. Category scores on the BenchLeader scale (50 is the average model, 15 points one standard deviation). High confidence means a lead of half a standard deviation or more; under one point is called either.

Use casePickWhyConfidence
CodingClaude Fable 5.175 vs 62 category score; Arena Coding 1538 vs 1460High
Agents & tool useo370 vs 61 category scoreHigh
MathsClaude Fable 5.173 vs 71 category score; Arena Maths 1529 vs 1448Medium
ReasoningClaude Fable 5.177 vs 52 category score; CritPt 29.7% vs 1.1%High
KnowledgeClaude Fable 5.178 vs 55 category score; AA-Omniscience 43.5 vs -15.6High
Long documentsClaude Fable 5.168 vs 62 category score; AA-LCR 85.3% vs 74.7%Medium
Images and other mediaClaude Fable 5.167 vs 57 category score; Arena Vision 1320 vs 1214High
Chat quality (human preference)Claude Fable 5.170 vs 61 on Arena votesHigh
Lowest costo3$3.50 vs $20.00 per 1M blended; agentic coding session $0.152 vs $0.800–
Fastest first answero36.9 s (o3) vs 194.4 s (Claude Fable 5.1 (max)) to the first answer token–
High volume on a budgetNeither flagshipA smaller model is usually the better fit: Cheapest good LLMs, Fastest LLMs–

Key differences

  • Claude Fable 5.1 (max) leads on quality: 70.5 vs 59.5.
  • Claude Fable 5.1 (max) is stronger in coding, composite, human preference, knowledge, long context, maths, multimodal, reasoning.
  • o3 is stronger in agents & tools, instruction following.
  • o3 is 5.7× cheaper ($3.50 vs $20.00 per 1M blended).
  • o3 streams 2.4× faster (166 vs 70 tokens per second).

At a glance

SpecClaude Fable 5.1o3
DeveloperAnthropicOpenAI
Released1 Sept 202616 Apr 2025
Context window (tokens)1,000,000200,000
Compared atClaude Fable 5.1 (max)o3
Open weightsNoNo
Price in / out / cached input per 1M$10.00 / $50.00 / $0.250$2.00 / $8.00 / $0.500

Category by category

Category scores on the BenchLeader scale: 50 is the average evaluated model, 15 points is one standard deviation. A gap under one point is called level.

CategoryClaude Fable 5.1 (max)o3Leader
Reasoning76.851.9Claude Fable 5.1
Coding74.961.8Claude Fable 5.1
Agents & tools60.570.3o3
Maths72.970.6Claude Fable 5.1
Knowledge77.555.3Claude Fable 5.1
Instruction following–65.1not comparable
Human preference70.061.3Claude Fable 5.1
Multimodal67.156.9Claude Fable 5.1
Long context67.862.3Claude Fable 5.1
Composite89.252.0Claude Fable 5.1

Where sources disagree

Across the 15 benchmarks both have, Claude Fable 5.1 leads 15, o3 leads 0. Every overall index that rates both puts Claude Fable 5.1 ahead.

Overall indexClaude Fable 5.1 (max)o3Leader
BenchLeader Index70.559.5Claude Fable 5.1
AA Intelligence Index v4.3.253.420.2Claude Fable 5.1
Arena Text15031432Claude Fable 5.1

Each publisher runs its own tasks, harnesses and effort settings, so their overall verdicts can differ; BenchLeader reconciles them on one scale. † measured at another effort setting of the same model (the publisher did not test the one compared here).

Price, speed and latency

List prices blended at three input tokens per output token. Per-task prices use the token counts on the methodology page; suite cost is what Artificial Analysis paid to run its whole Intelligence Index.

MeasureClaude Fable 5.1 (max)o3
Blended price per 1M tokens$20.00$3.50
Input / output per 1M$10.00 / $50.00$2.00 / $8.00
Cached input per 1M$0.250$0.500
Price per task: chat reply$0.019$0.0032
Price per task: summarize a 30-page report$0.150$0.029
Price per task: code edit$0.135$0.024
Price per task: agentic coding session$0.800$0.152
Price per task: structured extraction$0.030$0.0056
Cost to run a full benchmark suite$7.63–
Output speed70 tok/s166 tok/s
Time to first answer194.4 s6.9 s
Time to a complete answer201.5 s9.9 s

Each model is compared at its best-ranked reasoning-effort setting. Claude Fable 5.1 (max) scores 70.5 and takes 194 s to its first answer token; Claude Fable 5.1 (xhigh) scores 69.5 in 79 s, Claude Fable 5.1 (high) scores 69.4 in 20 s. o3 scores 59.5 and takes 7 s to its first answer token; o3 (high) scores 53.9 in 7 s, o3 (medium) scores 53.3 in 7 s. Higher effort means more thinking before the answer: better scores, longer waits and more tokens billed. How reasoning effort changes scores and cost.

Every benchmark

172 benchmarks, grouped by category; each name links to the board and its leaders. † measured at another effort setting of the same model, shown for reference and not counted as a win.

MetricPublisherClaude Fable 5.1 (max)o3
BenchLeader IndexBenchLeader70.559.5
Agents & tools scoreBenchLeader60.570.3
Coding scoreBenchLeader74.961.8
Composite scoreBenchLeader89.252.0
Human preference scoreBenchLeader70.061.3
Knowledge scoreBenchLeader77.555.3
Long context scoreBenchLeader67.862.3
Maths scoreBenchLeader72.970.6
Multimodal scoreBenchLeader67.156.9
Reasoning scoreBenchLeader76.851.9
Instruction following scoreBenchLeader–65.1
Blended price $/MBenchLeader$20.00$3.50
Output speedBenchLeader70 tok/s166 tok/s
Time to first answerBenchLeader194.4 s6.9 s
Context windowBenchLeader1,000,000 tokens200,000 tokens
Reasoning
GPQA DiamondEpoch AI Benchmarking Hub–81.8%†
Humanity's Last ExamScale AI / CAIS46.5%†20.3%†
SimpleBenchSimpleBench–53.1%†
Arena Hard PromptsArena (LMArena)15231442
LiveBench 2.0 ReasoningLiveBench91.7%†–
LiveBench 1.0 ReasoningLiveBench91.7%–
GPQA Diamond (AA)Artificial Analysis93.7%82.7%
Humanity's Last Exam (AA)Artificial Analysis59.1%20.1%
GPQA Diamond (Vals)Vals AI93.4%†84.1%†
Kagi LLM BenchmarkKagi LLM Benchmark–67.6%
GPQA Diamond (HELM)HELM Capabilities–75.3%
ARC-AGI-1ARC Prize97.5%60.8%†
ARC-AGI-2ARC Prize90.0%6.5%†
CritPtArtificial Analysis29.7%1.1%
MysteryMechanismVals AI47.8%†–
SciPredictScale AI SEAL–17.9%
Chess PuzzlesEpoch AI Benchmarking Hub48.0%36.0%†
Mystery Game PuzzlesEpoch AI Benchmarking Hub58.0%29.0%†
CL-benchEpoch AI Benchmarking Hub–17.8%†
LMCAEpoch AI Benchmarking Hub65.5%†39.7%†
DTBenchEpoch AI Benchmarking Hub97.6%†84.8%†
ForecastBenchForecastBench–64.6%
Coding
SWE-bench Verified (Epoch)Epoch AI Benchmarking Hub–62.3%†
SciCodeSciCode63.1%–
WeirdMLWeirdML92.9%52.4%†
Show all 172 benchmarks
MetricPublisherClaude Fable 5.1 (max)o3
Coding
FrontierCodeCognition50.9%†–
GSO-BenchGSO-Bench88.2%†8.8%†
Arena CodingArena (LMArena)15381460
Arena WebDevArena (LMArena)1743–
LiveBench 2.0 CodingLiveBench97.7%†–
LiveBench 1.0 CodingLiveBench86.4%–
LiveCodeBenchVals AI90.5%†83.9%†
IOIVals AI90.8%†–
Aider PolyglotAider polyglot leaderboard–81.3%
SWE-bench Verified (bash only)SWE-bench–58.4%
SWE-bench Verified (any scaffold)SWE-bench–58.4%
Code MigrationVals AI54.6%†–
ProgramBenchVals AI7.0%†–
SWE-bench MultimodalVals AI61.3%†–
Vibe Code Bench 1-100Vals AI28.0%†–
Vibe Code Bench v1.1Vals AI90.3%†–
SWE Atlas: Codebase QnAScale AI SEAL60.0%†–
SWE Atlas: RefactoringScale AI SEAL56.7%†–
SWE Atlas: Test WritingScale AI SEAL67.0%†–
MirrorCodeEpoch AI Benchmarking Hub73.3%†–
CadEvalEpoch AI Benchmarking Hub–74.0%†
CursorBenchCursor51.8%–
ALE-BenchEpoch AI Benchmarking Hub2143.2†933.5†
FrontierSWEEpoch AI Benchmarking Hub56.3%–
Terminal-Bench 4.0 (AA)Artificial Analysis52.0%–
Terminal-Bench 2.1 (AA)Artificial Analysis91.4%–
Startrise FrontendStartrise77.1%†–
FrontierCode 1.1 (AA)Artificial Analysis49.0%–
Agents & tools
Terminal-BenchTerminal-Bench57.9%–
GDPvalOpenAI–30.8%†
Remote Labor IndexScale AI / CAIS17.9%†–
APEX-AgentsMercor68.6%†–
Arena AgentArena (LMArena)13.9–
LiveBench Long AgenticLiveBench77.9%†–
LiveBench BrowserLiveBench89.8%†–
LiveBench Agentic CodingLiveBench66.1%–
Terminal-Bench HardArtificial Analysis–37.1%
τ²-Bench Telecom (AA)Artificial Analysis–80.7%
Terminal-Bench 2.1 (Vals)Vals AI85.0%†–
MCP AtlasScale AI SEAL87.2%†–
HiL-BenchScale AI SEAL61.5%†–
BFCL OverallBerkeley Function Calling Leaderboard–63.0%
GDPval-AA v2.1Artificial Analysis62.7%–
τ³-Banking (AA)Artificial Analysis47.2%–
ITBench SRE (AA)Artificial Analysis49.5%–
Analyst Agent (AA)Artificial Analysis57.5%–
CUA-benchVals AI13.2%–
CyberBenchVals AI70.4%†–
Finance Agent v2Vals AI58.9%†–
Harvey's Legal Agent Benchmark v1Vals AI6.7%†–
Legal Research BenchVals AI55.3%†–
Robo-benchVals AI5.8%–
SkillsBenchVals AI61.5%†–
SREBenchVals AI22.9%†–
Tax Agent BenchVals AI49.2%†–
Terminal-Bench 4.0 (Vals)Vals AI58.1%†–
Terminal-Bench ScienceVals AI40.0%†–
Time Horizon Index: KSPVals AI63.3%†–
Arena SearchArena (LMArena)1233†–
DeepResearch BenchDeepResearch Bench–45.2%†
METR Time HorizonsMETR–63.6%
Vending-Bench 2Andon Labs5421.6†–
AutomationBenchArtificial Analysis59.4%–
GDP.pdf (AA)Artificial Analysis26.2%–
Harvey LAB-AA v1.1Harvey6.4%–
AA-Briefcase v1.1Artificial Analysis1671–
Terminal-Bench-Science 0.1 (AA)Artificial Analysis43.3%–
CWE-Bench (AA)Artificial Analysis50.8%–
DeepSec-Bench (AA)Artificial Analysis23.5%–
CyberGym end-to-end (AA)Artificial Analysis0.8%–
BrowseComp-PlusBrowseComp-Plus–50.5%
Maths
FrontierMath Tiers 1–3Epoch AI Benchmarking Hub90.2%33.3%†
FrontierMath Tier 4Epoch AI Benchmarking Hub87.8%–
OTIS Mock AIMEEpoch AI Benchmarking Hub100.0%83.9%†
MATH Level 5Epoch AI Benchmarking Hub–97.8%†
ProofBenchVals AI100.0%–
LiveBench MathematicsLiveBench97.0%–
AIME (Vals)Vals AI–85.3%†
MGSMVals AI–91.8%†
IMO 2025MathArena–16.7%†
Omni-MATH (HELM)HELM Capabilities–71.4%
MATH 500Vals AI–94.6%†
Arena MathsArena (LMArena)15291448
Knowledge
SimpleQA VerifiedEpoch AI Benchmarking Hub70.8%49.4%†
LiveBench 2.0 Data AnalysisLiveBench80.3%†–
LiveBench ResearchLiveBench82.0%†–
LiveBench 1.0 Data AnalysisLiveBench80.3%–
AA-OmniscienceArtificial Analysis43.5-15.6
MMLU-ProVals AI92.4%†85.6%†
LegalBenchVals AI88.5%†83.8%†
CorpFinVals AI–59.7%†
TaxEvalVals AI76.0%†74.6%†
MedQAVals AI–96.1%†
PRBench FinanceScale AI SEAL50.8%†47.7%
PRBench LegalScale AI SEAL51.6%†48.6%
MultiNRCScale AI SEAL–45.5%†
MMLU-Pro (HELM)HELM Capabilities–85.9%
Excel Modeling BenchmarkVals AI76.7%†–
Excel Modeling Benchmark v1.1Vals AI76.7%†–
MedCodeVals AI53.5%†47.3%†
MedScribeVals AI91.3%†76.7%†
Public Benefits Bench v1.1Vals AI74.9%†–
EBR-benchEpoch AI Benchmarking Hub57.1%–
GDP.pdfEpoch AI Benchmarking Hub27.6%–
AA-Omniscience: accuracyArtificial Analysis67.2%38.6%
AA-Omniscience: non-hallucinationArtificial Analysis27.4%11.9%
Instruction following
LiveBench LanguageLiveBench89.5%–
LiveBench Instruction FollowingLiveBench73.0%–
IFBenchArtificial Analysis–71.4%
MultiChallengeScale AI SEAL–56.6%†
TutorBenchScale AI SEAL–52.1%†
IFEval (HELM)HELM Capabilities–86.9%
WildBench (HELM)HELM Capabilities–86.1%
Arena Instruction FollowingArena (LMArena)15011403
Human preference
Arena TextArena (LMArena)15031432
Arena Creative WritingArena (LMArena)14871383
Arena Multi-turnArena (LMArena)14881420
Arena Longer QueriesArena (LMArena)15111411
Lech Mazur Creative WritingLech Mazur–83.9%†
Multimodal
Arena VisionArena (LMArena)13201214
LiveBench DesignLiveBench83.4%†–
MMMU-ProArtificial Analysis–70.1%
VISTAScale AI SEAL–50.1%†
MMMU (validation)MMMU–82.9%
MMMU-Pro (official)MMMU–76.4%
MMMU-Pro (Vals)Vals AI90.6%†80.4%†
MortgageTaxVals AI70.8%†65.7%†
SAGEVals AI48.5%†41.8%†
VTBScale AI SEAL–13.7%
GeoBenchGeoBench–60.0%†
VPCTEpoch AI Benchmarking Hub–52.0%†
Blueprint-Bench 2Epoch AI Benchmarking Hub41.9%†–
AA-3DArtificial Analysis1135–
Long context
Fiction.LiveBench 120kFiction.live–100.0%†
AA-LCRArtificial Analysis85.3%74.7%
Arena DocumentArena (LMArena)1493–
MLCRArtificial Analysis15.6%–
Composite
Epoch Capabilities IndexEpoch AI Benchmarking Hub166.5†146.7
LiveBench 2.0LiveBench85.7%†–
LiveBench 1.0LiveBench83.4%–
AA Intelligence Index v4.3.2Artificial Analysis53.420.2
HELM Capabilities meanHELM Capabilities–81.1%
Vals RSI IndexVals AI36.1%–
AA Cyber IndexArtificial Analysis25.0–
Safety & honesty
FORTRESSScale AI SEAL13.7%†16.0%
MASKScale AI SEAL–84.5%†
PropensityBenchScale AI SEAL–10.5%

Data as of 2026-10-26. Best configuration of each model; every score links to its source on the model pages.

What changed

  • Claude Fable 5.1 (max): 2 new results (Robo-bench, Vals RSI Index).
  • Claude Fable 5.1 (max): 1 score revision.
  • Claude Fable 5.1 (max): 1 score revision.
  • o3: 1 score revision.
  • Claude Fable 5.1 (max): BenchLeader Index 70.0 → 70.6.
  • Claude Fable 5.1 (max): 2 score revisions.
  • Claude Fable 5.1 (max): 1 score revision.
  • o3: 1 new result (PRBench Legal).
  • Claude Fable 5.1 (max): BenchLeader Index 70.9 → 70.0.
  • Claude Fable 5.1 (max): 7 new results (FrontierCode 1.1 (AA), Terminal-Bench-Science 0.1 (AA), AA Cyber Index…).

Rankings: Best LLM overall · Best LLM for coding · Best LLM for agents · Best cheap LLMs

Claude Fable 5.1 vs o3: questions

Is Claude Fable 5.1 better than o3?
Claude Fable 5.1 (max) leads on quality: 70.5 vs 59.5. The BenchLeader Index combines every independent quality benchmark; Claude Fable 5.1 (max) is ahead overall as of 2026-10-26, but check the category scores for your use.
Which is cheaper, Claude Fable 5.1 or o3, and will that change?
o3 is cheaper today: $3.50 against $20.00 per million tokens, blended at three input tokens per output token. No price change has been announced for either.
Is Claude Fable 5.1 better than o3 for coding?
Claude Fable 5.1 scores higher in coding (75 vs 62 on the category index, where 50 is average). On Arena Coding, the top shared coding benchmark, it is 1538 for Claude Fable 5.1 against 1460 for o3.
Is Claude Fable 5.1 better than o3 for agents and tool use?
o3 scores higher in agentic tasks (70 vs 61 on the category index, where 50 is average).
Which is better for long documents?
Claude Fable 5.1 scores higher on long-context benchmarks (68 vs 62). Claude Fable 5.1 accepts more context: 1,000,000 against 200,000 tokens for o3.
Which has lower latency?
o3 answers first: 6.9 s against 194.4 s to the first answer token, as Artificial Analysis measures it. Reasoning effort drives most of this: a higher setting thinks longer before it answers.
Which is faster, Claude Fable 5.1 or o3?
o3 streams faster: 166 against 70 output tokens per second.
Do independent benchmarks agree on Claude Fable 5.1 vs o3?
Across the 15 benchmarks both have, Claude Fable 5.1 leads 15, o3 leads 0. Every overall index that rates both puts Claude Fable 5.1 ahead.
When was Claude Fable 5.1 released?
Claude Fable 5.1 was released on 1 Sept 2026.