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Claude Fable 5 vs Claude Sonnet 5.5

Claude Sonnet 5.5 leads Claude Fable 5 on coding, 87.3 to 79.3 on the Vibe Coding Index, and Claude Sonnet 5.5 costs 5.0x less per output token ($10.00 vs $50.00 per million). Updated October 22, 2026; 84 benchmarks have a result for both.

Replace Claude Fable 5 Replace Claude Sonnet 5.5
Claude Fable 5Anthropic
Coding
79.3
Overall
79.0
Output $/M
$50.00
45
Claude Sonnet 5.5Anthropic
Coding
87.3
Overall
82.8
Output $/M
$10.00
37
vs boards won of 84 shared, 2 tied

Claude Fable 5 or Claude Sonnet 5.5: which to pick

Pick Claude Sonnet 5.5 for coding: it scores 87.3 on the Vibe Coding Index against 79.3 for Claude Fable 5, though on 5 benchmarks against 6.

Pick Claude Fable 5 for work measured by LiveBench coding or FrontierCode, where it leads.

Model AClaude Fable 5Anthropic79.3/1006 independent benchmarks$2.16 per solved taskModel BClaude Sonnet 5.5Anthropic87.3/1005 independent benchmarksNo cost per solved task
Shared results
84
Claude Fable 5 only
43
Claude Sonnet 5.5 only
12
Like-for-like categories
8 of 9

Only benchmarks that tested both models count toward a pick; a result only one model has is shown but not compared.

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 79.3 from 6 benchmarks, Claude Sonnet 5.5 87.3 from 5 benchmarks.
Widest category
Agentic work, 10.8 points apart on average over 12 shared benchmarks.
Widest single gap
Furniture assembly: Claude Fable 5 35.8% against Claude Sonnet 5.5 75.0%, 39.2 points apart on a 0 to 100 scale.
Output price
Claude Fable 5 $50.00 against Claude Sonnet 5.5 $10.00 per million output tokens, 5.0x 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 5BarsClaude Sonnet 5.5Ties
Coding5101 tie
Intelligence02
Agentic work48
Reasoning64
Math321 tie
Knowledge60
Web design07
General214
All shared boards45372 ties
CodingLike-for-likeSix of these boards feed the Vibe Coding Index510
Coding benchmarks for Claude Fable 5 and Claude Sonnet 5.5
BenchmarkClaude Fable 5Claude Sonnet 5.5Leader
LiveBench coding98.3%94.7%Claude Fable 5
LMArena WebDev16241768Claude Sonnet 5.5
AA Coding Index76.5Not measuredOnly Claude Fable 5 measured
LiveCodeBench (Vals AI)89.8%Not measuredOnly Claude Fable 5 measured
SWE-bench Verified (Vals AI)95.0%Not measuredOnly Claude Fable 5 measured
Terminal-Bench 4 (Vals AI)41.4%64.1%Claude Sonnet 5.5
Vibe Code Bench (Vals AI)90.3%92.4%Claude Sonnet 5.5
Code migration (Vals AI)55.1%69.8%Claude Sonnet 5.5
ProgramBench (Vals AI)2.0%6.5%Claude Sonnet 5.5
IOI (Vals AI)Not measured83.1%Only Claude Sonnet 5.5 measured
Terminal-Bench 2.1 (Vals AI)80.5%83.2%Claude Sonnet 5.5
SWE-bench Multimodal (Vals AI)Not measured58.3%Only Claude Sonnet 5.5 measured
CyberBench (Vals AI)Not measured59.6%Only Claude Sonnet 5.5 measured
SciCode61.0%61.0%Tie
Terminal-Bench Hard (Artificial Analysis run)62.9%Not measuredOnly Claude Fable 5 measured
FrontierCode53.5%52.1%Claude Fable 5
FrontierSWE47.0%61.9%Claude Sonnet 5.5
GSO-Bench78.4%Not measuredOnly Claude Fable 5 measured
WeirdML91.9%Not measuredOnly Claude Fable 5 measured
MirrorCode63.9%Not measuredOnly Claude Fable 5 measured
ALE-Bench2041.31819.1Claude Fable 5
LMArena Text: coding15181513Claude Fable 5
LMArena Text: software and IT15131504Claude Fable 5
LMArena WebDev: React16311817Claude Sonnet 5.5
LMArena WebDev: HTML16511741Claude Sonnet 5.5
LMArena WebDev: from an image16231737Claude Sonnet 5.5
SciCodeNot measured13.8%Only Claude Sonnet 5.5 measured
Neither model has a result on the other 12 boards here
IntelligenceLike-for-likePublic boards, shown as published, kept out of the index02
Intelligence benchmarks for Claude Fable 5 and Claude Sonnet 5.5
BenchmarkClaude Fable 5Claude Sonnet 5.5Leader
AA Intelligence Index49.656.0Claude Sonnet 5.5
Epoch Capabilities Index163.4166.2Claude Sonnet 5.5
Agentic workLike-for-likePublic boards, shown as published, kept out of the index48
Agentic work benchmarks for Claude Fable 5 and Claude Sonnet 5.5
BenchmarkClaude Fable 5Claude Sonnet 5.5Leader
AA Agentic Index50.7Not measuredOnly Claude Fable 5 measured
Design Arena: agents building web apps12611305Claude Sonnet 5.5
Design Arena: agents building full-stack apps1280Not measuredOnly Claude Fable 5 measured
Design Arena: agents building mobile apps12641260Claude Fable 5
Design Arena: agents building Android apps1284Not measuredOnly Claude Fable 5 measured
Design Arena: agents building Godot games1292Not measuredOnly Claude Fable 5 measured
Design Arena: agents building games1285Not measuredOnly Claude Fable 5 measured
Design Arena: HTML slides1227Not measuredOnly Claude Fable 5 measured
Design Arena: PowerPoint slides1270Not measuredOnly Claude Fable 5 measured
Design Arena: spreadsheetsNot measured1260Only Claude Sonnet 5.5 measured
LiveBench research86.9%83.6%Claude Fable 5
LiveBench browser92.0%84.0%Claude Fable 5
LiveBench long agentic53.2%78.8%Claude Sonnet 5.5
SREBench (Vals AI)Not measured30.1%Only Claude Sonnet 5.5 measured
Finance Agent (Vals AI)56.3%58.1%Claude Sonnet 5.5
Tax Agent Bench (Vals AI)38.3%42.0%Claude Sonnet 5.5
Legal Research Bench (Vals AI)49.5%48.1%Claude Fable 5
Harvey's Legal Agent Benchmark (Vals AI)Not measured10.4%Only Claude Sonnet 5.5 measured
Excel Modeling Benchmark (Vals AI)73.7%75.7%Claude Sonnet 5.5
BioMysteryBench (Vals AI)Not measured81.1%Only Claude Sonnet 5.5 measured
Terminal-Bench-Science (Vals AI)15.7%47.1%Claude Sonnet 5.5
Vals Science IndexNot measured59.1%Only Claude Sonnet 5.5 measured
τ²-Bench Telecom98.5%Not measuredOnly Claude Fable 5 measured
APEX-Agents63.6%75.5%Claude Sonnet 5.5
Remote Labor Index16.1%Not measuredOnly Claude Fable 5 measured
PostTrainBench41.8%Not measuredOnly Claude Fable 5 measured
SpireClimbNot measured1.3%Only Claude Sonnet 5.5 measured
Vending-Bench 2$5,680$11,165Claude Sonnet 5.5
LMArena Search1229Not measuredOnly Claude Fable 5 measured
Neither model has a result on the other 12 boards here
ReasoningLike-for-likePublic boards, shown as published, kept out of the index64
Reasoning benchmarks for Claude Fable 5 and Claude Sonnet 5.5
BenchmarkClaude Fable 5Claude Sonnet 5.5Leader
GPQA Diamond93.2%Not measuredOnly Claude Fable 5 measured
LiveBench reasoning89.7%91.6%Claude Sonnet 5.5
MysteryMechanism (Vals AI)Not measured49.1%Only Claude Sonnet 5.5 measured
MMMU Pro (Vals AI)89.3%Not measuredOnly Claude Fable 5 measured
GPQA Diamond (Artificial Analysis run)92.6%Not measuredOnly Claude Fable 5 measured
Humanity's Last Exam (Artificial Analysis run)55.5%55.0%Claude Fable 5
GPQA Diamond (Epoch AI run)85.9%95.6%Claude Sonnet 5.5
ARC-AGI98.5%Not measuredOnly Claude Fable 5 measured
ARC-AGI-289.2%Not measuredOnly Claude Fable 5 measured
SimpleBench81.9%Not measuredOnly Claude Fable 5 measured
Chess puzzles47.0%59.0%Claude Sonnet 5.5
Mystery game puzzles52.0%65.0%Claude Sonnet 5.5
EBR-bench39.5%Not measuredOnly Claude Fable 5 measured
LMArena Text: hard prompts15071494Claude Fable 5
LMArena Text: expert15341531Claude Fable 5
LMArena Text: hard prompts in English15091502Claude Fable 5
LMArena Vision: diagrams13571329Claude Fable 5
LMArena Vision: homework13611331Claude Fable 5
Kagi LLM Benchmark91.4%Not measuredOnly Claude Fable 5 measured
Neither model has a result on the other 3 boards here
MathLike-for-likePublic boards, shown as published, kept out of the index32
Math benchmarks for Claude Fable 5 and Claude Sonnet 5.5
BenchmarkClaude Fable 5Claude Sonnet 5.5Leader
OTIS Mock AIME100.0%100.0%Tie
FrontierMath, tiers 1 to 387.0%88.8%Claude Sonnet 5.5
FrontierMath, tier 490.2%80.5%Claude Fable 5
ProofBench95.0%100.0%Claude Sonnet 5.5
LMArena Text: math15161497Claude Fable 5
LMArena Text: mathematical work15151510Claude Fable 5
Neither model has a result on the other 7 boards here
KnowledgeLike-for-likePublic boards, shown as published, kept out of the index60
Knowledge benchmarks for Claude Fable 5 and Claude Sonnet 5.5
BenchmarkClaude Fable 5Claude Sonnet 5.5Leader
MMLU Pro91.5%Not measuredOnly Claude Fable 5 measured
LegalBench (Vals AI)88.6%Not measuredOnly Claude Fable 5 measured
CorpFin (Vals AI)71.8%Not measuredOnly Claude Fable 5 measured
TaxEval (Vals AI)76.9%Not measuredOnly Claude Fable 5 measured
MortgageTax (Vals AI)68.9%Not measuredOnly Claude Fable 5 measured
MedCode (Vals AI)56.1%52.9%Claude Fable 5
SimpleQA Verified70.7%46.5%Claude Fable 5
LMArena Text: science15061483Claude Fable 5
LMArena Text: medicine and healthcare14801464Claude Fable 5
LMArena Text: legal and government14981483Claude Fable 5
LMArena Text: business and finance14801468Claude Fable 5
Neither model has a result on the other 7 boards here
Web designLike-for-likePublic boards, shown as published, kept out of the index07
Web design benchmarks for Claude Fable 5 and Claude Sonnet 5.5
BenchmarkClaude Fable 5Claude Sonnet 5.5Leader
Design Arena: websites12951326Claude Sonnet 5.5
Design Arena: UI components13161368Claude Sonnet 5.5
Design Arena: game dev13351471Claude Sonnet 5.5
Design Arena: data viz13041392Claude Sonnet 5.5
Design Arena: 3D13181445Claude Sonnet 5.5
Design Arena: all code categories13101364Claude Sonnet 5.5
Design Arena: SVG1302Not measuredOnly Claude Fable 5 measured
Design Arena: ASCII art1329Not measuredOnly Claude Fable 5 measured
LiveBench design84.7%85.0%Claude Sonnet 5.5
GeneralLike-for-likePublic boards, shown as published, kept out of the index214
General benchmarks for Claude Fable 5 and Claude Sonnet 5.5
BenchmarkClaude Fable 5Claude Sonnet 5.5Leader
Vals IndexNot measured70.8%Only Claude Sonnet 5.5 measured
LiveBench data analysis80.5%59.5%Claude Fable 5
Public Benefits Bench (Vals AI)70.4%67.2%Claude Fable 5
SAGE (Vals AI)51.9%51.8%Claude Fable 5
MedScribe (Vals AI)88.5%91.1%Claude Sonnet 5.5
Vals Multimodal Index74.2%Not measuredOnly Claude Fable 5 measured
IFBench63.5%Not measuredOnly Claude Fable 5 measured
Long context reasoning (AA-LCR)82.3%82.7%Claude Sonnet 5.5
DTBench98.4%97.3%Claude Fable 5
LMCA61.2%68.3%Claude Sonnet 5.5
Surface Evolver Bench95.0%Not measuredOnly Claude Fable 5 measured
Furniture assembly35.8%75.0%Claude Sonnet 5.5
LMArena Text14911473Claude Fable 5
LMArena Text: instruction following15021492Claude Fable 5
LMArena Text: creative writing14941467Claude Fable 5
LMArena Vision13251287Claude Fable 5
LMArena Text: English14981484Claude Fable 5
LMArena Text: non-English14821456Claude Fable 5
LMArena Text: Chinese15431535Claude Fable 5
LMArena Text: German1486Not measuredOnly Claude Fable 5 measured
LMArena Text: Japanese1504Not measuredOnly Claude Fable 5 measured
LMArena Text: Korean1487Not measuredOnly Claude Fable 5 measured
LMArena Text: French15051499Claude Fable 5
LMArena Text: Spanish14981451Claude Fable 5
LMArena Text: Russian15031454Claude Fable 5
LMArena Text: Polish1494Not measuredOnly Claude Fable 5 measured
LMArena Text: multi-turn15041465Claude Fable 5
LMArena Text: longer queries15101495Claude Fable 5
LMArena Text: writing and language15011474Claude Fable 5
LMArena Text: entertainment and media14821461Claude Fable 5
LMArena Vision: English13231289Claude Fable 5
LMArena Vision: Chinese1373Not measuredOnly Claude Fable 5 measured
LMArena Vision: reading text13371297Claude Fable 5
LMArena Vision: humor1341Not measuredOnly Claude Fable 5 measured
LMArena Vision: creative writing13381242Claude Fable 5
LMArena Document1496Not measuredOnly Claude Fable 5 measured
Neither model has a result on the other 10 boards here
Image generationNot comparablePublic boards, shown as published, kept out of the index0 boards, none shared
Image generation benchmarks for Claude Fable 5 and Claude Sonnet 5.5
BenchmarkClaude Fable 5Claude Sonnet 5.5Leader
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$0.035Fits in one request
Claude Sonnet 5.5$0.0070Fits in one request

Claude Sonnet 5.5 costs less

Repository review

50K input + 3K output tokens

Claude Fable 5$0.650Fits in one request
Claude Sonnet 5.5$0.130Fits in one request

Claude Sonnet 5.5 costs less

Agent loop

200K input + 10K output tokens

Claude Fable 5$2.50Fits in one request
Claude Sonnet 5.5$0.500Fits in one request

Claude Sonnet 5.5 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 and Claude Sonnet 5.5
SpecificationAnthropic Claude Fable 5Anthropic Claude Sonnet 5.5
MakerAnthropicAnthropic
WeightsNo public weights listedNo public weights listed
ReleasedJune 9, 2026September 28, 2026
Context window1M1M
Input $/Mtok$10.00$2.00
Output $/Mtok$50.00$10.00
Coding index79.387.3
Independent measurements behind it65
Cost per solved task$2.16Not computable
SourceOpenRouter listingOpenRouter listing

Questions

Is Claude Fable 5 better than Claude Sonnet 5.5 for coding?

Pick Claude Sonnet 5.5 for coding: it scores 87.3 on the Vibe Coding Index against 79.3 for Claude Fable 5, though on 5 benchmarks against 6. Pick Claude Fable 5 for work measured by LiveBench coding or FrontierCode, where it leads.

Which is cheaper, Claude Fable 5 or Claude Sonnet 5.5?

Claude Fable 5 costs $10.00 per million input tokens and $50.00 per million output tokens; Claude Sonnet 5.5 costs $2.00 and $10.00. Cost per solved task is known for Claude Fable 5 only.

Which has the bigger context window, Claude Fable 5 or Claude Sonnet 5.5?

Neither: both take 1M tokens.

How many benchmarks is the Claude Fable 5 vs Claude Sonnet 5.5 comparison based on?

84 benchmarks have a result for both models as of October 22, 2026. Claude Fable 5's coding index rests on 6 independent benchmarks and Claude Sonnet 5.5's on 5. 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-vs-claude-sonnet-5-5">LLMBenchmark.ai, Claude Fable 5 vs Claude Sonnet 5.5</a></p>