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Claude Fable 5.1 vs Claude Opus 5

Updated October 21, 2026. 117 benchmarks have a result for both. Coding is ranked on the Vibe Coding Index; every other board is shown as published.

Replace Claude Fable 5.1 Replace Claude Opus 5
Claude Fable 5.1Anthropic
Coding
89.1
Overall
53.4
Output $/M
$50.00
79
Claude Opus 5Anthropic
Coding
81.8
Overall
50.8
Output $/M
$25.00
34
vs boards won of 117 shared, 4 tied

Decision reading

Pick Claude Fable 5.1 for coding: it scores 89.1 on the Vibe Coding Index against 81.8 for Claude Opus 5.

Pick Claude Opus 5 when output tokens cost 2.0x less, or when what matters is Code migration (Vals AI) or Vibe Code Bench 1-100 (Vals AI), where it leads.

Model AClaude Fable 5.1Anthropic89.1/1002 independent benchmarksNo cost per solved taskModel BClaude Opus 5Anthropic81.8/1002 independent benchmarks$1.33 per solved task
Shared results
117
Claude Fable 5.1 only
7
Claude Opus 5 only
13
Like-for-like categories
8 of 9

Shared results can support a head-to-head reading. Results only one model has describe coverage, not superiority.

Which one for your work

Each card is decided by one number both models carry. Where only one has it, the card says so and makes no call.

At a glance

Coding index
Claude Fable 5.1 89.1 from 2 benchmarks, Claude Opus 5 81.8 from 2 benchmarks.
Widest category
Agentic work, 9.7 points apart on average over 20 shared benchmarks.
Widest single gap
Time Horizon Index (Vals AI): Claude Fable 5.1 63.3% against Claude Opus 5 18.8%, 44.5 points apart on a 0 to 100 scale.
Output price
Claude Fable 5.1 $50.00 against Claude Opus 5 $25.00 per million output tokens, 2.0x apart.
Context window
Both take 1M tokens.

Benchmark by benchmark

First the score: boards each model leads, per category, where both have a result. Then every board, a category to a fold; bars are each result on a 0 to 100 scale, so compare the two in a row, not one row with another.

Boards won, where both have a result
CategoryClaude Fable 5.1BarsClaude Opus 5Ties
Coding185
Intelligence20
Agentic work1631 tie
Reasoning853 ties
Math42
Knowledge64
Web design63
General1912
All shared boards79344 ties
CodingLike-for-likeFour of these boards feed the Vibe Coding Index185
Coding benchmarks for Claude Fable 5.1 and Claude Opus 5
BenchmarkClaude Fable 5.1Claude Opus 5Leader
LiveBench coding97.7%90.8%Claude Fable 5.1
LMArena WebDev17431689Claude Fable 5.1
AA Coding Index81.678.0Claude Fable 5.1
LiveCodeBench (Vals AI)90.5%89.0%Claude Fable 5.1
SWE-bench Verified (Vals AI)Not measured97.0%Only Claude Opus 5 measured
Terminal-Bench 4 (Vals AI)58.1%53.5%Claude Fable 5.1
Vibe Code Bench (Vals AI)90.3%88.4%Claude Fable 5.1
Code migration (Vals AI)54.6%57.5%Claude Opus 5
ProgramBench (Vals AI)7.0%3.0%Claude Fable 5.1
IOI (Vals AI)90.8%84.3%Claude Fable 5.1
Terminal-Bench 2.1 (Vals AI)85.0%84.6%Claude Fable 5.1
SWE-bench Multimodal (Vals AI)61.3%Not measuredOnly Claude Fable 5.1 measured
Vibe Code Bench 1-100 (Vals AI)28.0%28.5%Claude Opus 5
SkillsBench (Vals AI)61.5%60.4%Claude Fable 5.1
CyberBench (Vals AI)70.4%65.4%Claude Fable 5.1
SciCode63.1%56.4%Claude Fable 5.1
FrontierCode50.9%53.4%Claude Opus 5
FrontierSWE56.3%52.0%Claude Fable 5.1
GSO-Bench88.2%Not measuredOnly Claude Fable 5.1 measured
WeirdML92.9%91.8%Claude Fable 5.1
MirrorCode73.3%Not measuredOnly Claude Fable 5.1 measured
ALE-Bench2143.22164.6Claude Opus 5
LMArena Text: coding15321533Claude Opus 5
LMArena Text: software and IT15301527Claude Fable 5.1
LMArena WebDev: React17921711Claude Fable 5.1
LMArena WebDev: HTML16841680Claude Fable 5.1
LMArena WebDev: from an image17221662Claude Fable 5.1
Neither model has a result on the other 11 boards here
IntelligenceLike-for-likePublic boards, shown as published, kept out of the index20
Intelligence benchmarks for Claude Fable 5.1 and Claude Opus 5
BenchmarkClaude Fable 5.1Claude Opus 5Leader
AA Intelligence Index53.450.8Claude Fable 5.1
Epoch Capabilities Index166.5163.9Claude Fable 5.1
Agentic workLike-for-likePublic boards, shown as published, kept out of the index163
Agentic work benchmarks for Claude Fable 5.1 and Claude Opus 5
BenchmarkClaude Fable 5.1Claude Opus 5Leader
AA Agentic Index57.956.5Claude Fable 5.1
Design Arena: agents building web apps13181266Claude Fable 5.1
Design Arena: agents building full-stack apps13261306Claude Fable 5.1
Design Arena: agents building mobile apps12671348Claude Opus 5
Design Arena: agents building Android appsNot measured1258Only Claude Opus 5 measured
Design Arena: agents building Godot games13271279Claude Fable 5.1
Design Arena: agents building gamesNot measured1261Only Claude Opus 5 measured
Design Arena: PowerPoint slides13281265Claude Fable 5.1
Design Arena: spreadsheets1374Not measuredOnly Claude Fable 5.1 measured
LiveBench research82.0%88.9%Claude Opus 5
LiveBench browser100.0%84.0%Claude Fable 5.1
LiveBench long agentic80.8%62.1%Claude Fable 5.1
SREBench (Vals AI)22.9%12.2%Claude Fable 5.1
Finance Agent (Vals AI)58.9%58.6%Claude Fable 5.1
Tax Agent Bench (Vals AI)49.2%45.5%Claude Fable 5.1
Legal Research Bench (Vals AI)55.3%55.3%Tie
Excel Modeling Benchmark (Vals AI)76.7%73.6%Claude Fable 5.1
BioMysteryBench (Vals AI)Not measured79.3%Only Claude Opus 5 measured
Terminal-Bench-Science (Vals AI)40.0%27.1%Claude Fable 5.1
Vals Science IndexNot measured47.9%Only Claude Opus 5 measured
Time Horizon Index (Vals AI)63.3%18.8%Claude Fable 5.1
CUA-bench (Vals AI)13.2%9.0%Claude Fable 5.1
Robo-bench (Vals AI)5.8%Not measuredOnly Claude Fable 5.1 measured
APEX-Agents68.6%65.8%Claude Fable 5.1
Remote Labor Index17.9%Not measuredOnly Claude Fable 5.1 measured
OSWorld 2.0Not measured31.4%Only Claude Opus 5 measured
BALROGNot measured63.4%Only Claude Opus 5 measured
PostTrainBenchNot measured35.0%Only Claude Opus 5 measured
SpireClimb2.0%Not measuredOnly Claude Fable 5.1 measured
Vending-Bench 2$5,422$11,182Claude Opus 5
LMArena Search12461242Claude Fable 5.1
Neither model has a result on the other 8 boards here
ReasoningLike-for-likePublic boards, shown as published, kept out of the index85
Reasoning benchmarks for Claude Fable 5.1 and Claude Opus 5
BenchmarkClaude Fable 5.1Claude Opus 5Leader
GPQA Diamond93.4%93.4%Tie
LiveBench reasoning91.7%91.2%Claude Fable 5.1
MysteryMechanism (Vals AI)47.8%37.4%Claude Fable 5.1
MMMU Pro (Vals AI)90.6%89.9%Claude Fable 5.1
GPQA Diamond (Artificial Analysis run)93.7%93.7%Tie
Humanity's Last Exam (Artificial Analysis run)59.1%54.9%Claude Fable 5.1
GPQA Diamond (Epoch AI run)Not measured93.9%Only Claude Opus 5 measured
ARC-AGI97.5%97.5%Tie
ARC-AGI-290.0%90.4%Claude Opus 5
SimpleBenchNot measured80.6%Only Claude Opus 5 measured
Chess puzzles48.0%43.0%Claude Fable 5.1
Mystery game puzzles58.0%59.0%Claude Opus 5
EBR-bench57.1%45.7%Claude Fable 5.1
LMArena Text: hard prompts15281527Claude Fable 5.1
LMArena Text: expert15441554Claude Opus 5
LMArena Text: hard prompts in English15221523Claude Opus 5
LMArena Vision: diagrams13431348Claude Opus 5
LMArena Vision: homework13451338Claude Fable 5.1
Neither model has a result on the other 3 boards here
MathLike-for-likePublic boards, shown as published, kept out of the index42
Math benchmarks for Claude Fable 5.1 and Claude Opus 5
BenchmarkClaude Fable 5.1Claude Opus 5Leader
OTIS Mock AIME100.0%98.9%Claude Fable 5.1
FrontierMath, tiers 1 to 390.2%85.6%Claude Fable 5.1
FrontierMath, tier 487.8%73.2%Claude Fable 5.1
ProofBench100.0%99.0%Claude Fable 5.1
LMArena Text: math15311533Claude Opus 5
LMArena Text: mathematical work15411544Claude Opus 5
Neither model has a result on the other 7 boards here
KnowledgeLike-for-likePublic boards, shown as published, kept out of the index64
Knowledge benchmarks for Claude Fable 5.1 and Claude Opus 5
BenchmarkClaude Fable 5.1Claude Opus 5Leader
MMLU Pro92.4%91.6%Claude Fable 5.1
LegalBench (Vals AI)88.5%87.0%Claude Fable 5.1
CorpFin (Vals AI)Not measured73.2%Only Claude Opus 5 measured
TaxEval (Vals AI)76.0%75.1%Claude Fable 5.1
MortgageTax (Vals AI)70.8%72.1%Claude Opus 5
MedCode (Vals AI)53.5%63.6%Claude Opus 5
SimpleQA Verified70.8%59.9%Claude Fable 5.1
LMArena Text: science15321531Claude Fable 5.1
LMArena Text: medicine and healthcare15311525Claude Fable 5.1
LMArena Text: legal and government15141530Claude Opus 5
LMArena Text: business and finance14931501Claude Opus 5
Neither model has a result on the other 6 boards here
Web designLike-for-likePublic boards, shown as published, kept out of the index63
Web design benchmarks for Claude Fable 5.1 and Claude Opus 5
BenchmarkClaude Fable 5.1Claude Opus 5Leader
Design Arena: websites13131309Claude Fable 5.1
Design Arena: UI components13381348Claude Opus 5
Design Arena: game dev13821339Claude Fable 5.1
Design Arena: data viz13441329Claude Fable 5.1
Design Arena: 3D13931335Claude Fable 5.1
Design Arena: all code categories13361324Claude Fable 5.1
Design Arena: SVG13011310Claude Opus 5
Design Arena: ASCII art13241352Claude Opus 5
LiveBench design83.4%83.0%Claude Fable 5.1
GeneralLike-for-likePublic boards, shown as published, kept out of the index1912
General benchmarks for Claude Fable 5.1 and Claude Opus 5
BenchmarkClaude Fable 5.1Claude Opus 5Leader
LiveBench data analysis80.3%74.6%Claude Fable 5.1
Public Benefits Bench (Vals AI)74.9%76.9%Claude Opus 5
SAGE (Vals AI)48.5%49.4%Claude Opus 5
MedScribe (Vals AI)91.3%91.0%Claude Fable 5.1
Vals Multimodal IndexNot measured73.9%Only Claude Opus 5 measured
Long context reasoning (AA-LCR)85.3%82.0%Claude Fable 5.1
DTBench97.6%97.9%Claude Opus 5
LMCA65.5%64.5%Claude Fable 5.1
Furniture assembly70.0%60.8%Claude Fable 5.1
LMArena Text15121509Claude Fable 5.1
LMArena Text: instruction following15181518Claude Fable 5.1
LMArena Text: creative writing15091493Claude Fable 5.1
LMArena Vision13191320Claude Opus 5
LMArena Text: English15061508Claude Opus 5
LMArena Text: non-English15081502Claude Fable 5.1
LMArena Text: Chinese15841573Claude Fable 5.1
LMArena Text: German14991527Claude Opus 5
LMArena Text: Japanese15621520Claude Fable 5.1
LMArena Text: Korean15171517Claude Opus 5
LMArena Text: French15231519Claude Fable 5.1
LMArena Text: Spanish15201523Claude Opus 5
LMArena Text: Russian15201507Claude Fable 5.1
LMArena Text: Polish15251522Claude Fable 5.1
LMArena Text: multi-turn14931500Claude Opus 5
LMArena Text: longer queries15241517Claude Fable 5.1
LMArena Text: writing and language15101499Claude Fable 5.1
LMArena Text: entertainment and media14971481Claude Fable 5.1
LMArena Vision: English13131315Claude Opus 5
LMArena Vision: Chinese13911400Claude Opus 5
LMArena Vision: reading text13271329Claude Opus 5
LMArena Vision: humor13181293Claude Fable 5.1
LMArena Vision: creative writing13301313Claude Fable 5.1
LMArena DocumentNot measured1516Only Claude Opus 5 measured
Neither model has a result on the other 13 boards here
Image generationNot comparablePublic boards, shown as published, kept out of the index0 boards, none shared
Image generation benchmarks for Claude Fable 5.1 and Claude Opus 5
BenchmarkClaude Fable 5.1Claude Opus 5Leader
Neither model has a result on 5 boards here

What each workload costs

Three fixed token mixes at each model's listed price, so per-token rates become a bill.

Chat turn

1K input + 500 output tokens

Claude Fable 5.1$0.035Fits in one request
Claude Opus 5$0.018Fits in one request

Claude Opus 5 costs less

Repository review

50K input + 3K output tokens

Claude Fable 5.1$0.650Fits in one request
Claude Opus 5$0.325Fits in one request

Claude Opus 5 costs less

Agent loop

200K input + 10K output tokens

Claude Fable 5.1$2.50Fits in one request
Claude Opus 5$1.25Fits in one request

Claude Opus 5 costs less

Listed OpenRouter rates, without cache or batch discounts. A workload that does not fit a model's context window would need splitting.

Specification differences

The leading value in a row is marked; a row with a missing value names no leader. Our two rows are marked in red.

Specifications of Claude Fable 5.1 and Claude Opus 5
SpecificationAnthropic Claude Fable 5.1Anthropic Claude Opus 5
MakerAnthropicAnthropic
WeightsNo public weights listedNo public weights listed
ReleasedSeptember 1, 2026July 24, 2026
Context window1M1M
Input $/Mtok$10.00$5.00
Output $/Mtok$50.00$25.00
Coding index89.181.8
Independent measurements behind it22
Cost per solved taskNot computable$1.33
SourceOpenRouter listingOpenRouter listing

Questions

Is Claude Fable 5.1 better than Claude Opus 5 for coding?

Pick Claude Fable 5.1 for coding: it scores 89.1 on the Vibe Coding Index against 81.8 for Claude Opus 5. Pick Claude Opus 5 when output tokens cost 2.0x less, or when what matters is Code migration (Vals AI) or Vibe Code Bench 1-100 (Vals AI), where it leads.

Which is cheaper, Claude Fable 5.1 or Claude Opus 5?

Claude Fable 5.1 costs $10.00 per million input tokens and $50.00 per million output tokens; Claude Opus 5 costs $5.00 and $25.00. Cost per solved task is known for Claude Opus 5 only.

Which has the bigger context window, Claude Fable 5.1 or Claude Opus 5?

Neither: both take 1M tokens.

How many benchmarks is the Claude Fable 5.1 vs Claude Opus 5 comparison based on?

117 benchmarks have a result for both models as of October 21, 2026. Claude Fable 5.1's coding index rests on 2 independent benchmarks and Claude Opus 5's on 2. Where only one model has a result, the page says so instead of naming a winner.

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<p style="font:13px/1.4 sans-serif;margin:6px 0 0">Source: <a href="https://llmbenchmark.ai/compare/claude-fable-5-1-vs-claude-opus-5">LLMBenchmark.ai, Claude Fable 5.1 vs Claude Opus 5</a></p>