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Claude Fable 5 vs GPT-5.4 Nano

Claude Fable 5 leads GPT-5.4 Nano on coding, 79.3 to 44.8 on the Vibe Coding Index, and GPT-5.4 Nano costs 40.0x less per output token ($1.25 vs $50.00 per million). Updated October 22, 2026; 82 benchmarks have a result for both.

Replace Claude Fable 5 Replace GPT-5.4 Nano
Claude Fable 5Anthropic
Coding
79.3
Overall
79.0
Output $/M
$50.00
81
GPT-5.4 NanoOpenAI
Coding
44.8
Overall
45.7
Output $/M
$1.25
1
vs boards won of 82 shared

Claude Fable 5 or GPT-5.4 Nano: which to pick

Pick Claude Fable 5 for coding: it scores 79.3 on the Vibe Coding Index against 44.8 for GPT-5.4 Nano.

Pick GPT-5.4 Nano for output tokens 40.0x cheaper ($1.25 vs $50.00 per million) and a lower cost per solved task ($0.14 against $2.16).

Model AClaude Fable 5Anthropic79.3/1006 independent benchmarks$2.16 per solved taskModel BGPT-5.4 NanoOpenAI44.8/1002 independent benchmarks$0.14 per solved task
Shared results
82
Claude Fable 5 only
45
GPT-5.4 Nano only
3
Like-for-like categories
7 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, GPT-5.4 Nano 44.8 from 2 benchmarks.
Widest category
Math, 43.1 points apart on average over 6 shared benchmarks.
Widest single gap
ProofBench: Claude Fable 5 95.0% against GPT-5.4 Nano 5.0%, 90.0 points apart on a 0 to 100 scale.
Output price
Claude Fable 5 $50.00 against GPT-5.4 Nano $1.25 per million output tokens, 40.0x apart.
Context window
Claude Fable 5 takes 1M tokens, GPT-5.4 Nano 400K.

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 5BarsGPT-5.4 NanoTies
Coding120
Intelligence20
Agentic work60
Reasoning150
Math60
Knowledge110
General291
All shared boards811
CodingLike-for-likeSix of these boards feed the Vibe Coding Index120
Coding benchmarks for Claude Fable 5 and GPT-5.4 Nano
BenchmarkClaude Fable 5GPT-5.4 NanoLeader
LiveBench coding98.3%Not measuredOnly Claude Fable 5 measured
LMArena WebDev1624Not measuredOnly Claude Fable 5 measured
AA Coding Index76.556.1Claude Fable 5
LiveCodeBench (Vals AI)89.8%84.0%Claude Fable 5
SWE-bench Verified (Vals AI)95.0%69.8%Claude Fable 5
Terminal-Bench 4 (Vals AI)41.4%Not measuredOnly Claude Fable 5 measured
Vibe Code Bench (Vals AI)90.3%26.1%Claude Fable 5
Code migration (Vals AI)55.1%14.5%Claude Fable 5
ProgramBench (Vals AI)2.0%Not measuredOnly Claude Fable 5 measured
Terminal-Bench 2.1 (Vals AI)80.5%41.6%Claude Fable 5
SciCode61.0%47.2%Claude Fable 5
Terminal-Bench Hard (Artificial Analysis run)62.9%42.4%Claude Fable 5
FrontierCode53.5%Not measuredOnly Claude Fable 5 measured
FrontierSWE47.0%Not measuredOnly Claude Fable 5 measured
GSO-Bench78.4%Not measuredOnly Claude Fable 5 measured
WeirdML91.9%49.2%Claude Fable 5
MirrorCode63.9%Not measuredOnly Claude Fable 5 measured
ALE-Bench2041.31004.5Claude Fable 5
LMArena Text: coding15181404Claude Fable 5
LMArena Text: software and IT15131402Claude Fable 5
LMArena WebDev: React1631Not measuredOnly Claude Fable 5 measured
LMArena WebDev: HTML1651Not measuredOnly Claude Fable 5 measured
LMArena WebDev: from an image1623Not measuredOnly Claude Fable 5 measured
Neither model has a result on the other 16 boards here
IntelligenceLike-for-likePublic boards, shown as published, kept out of the index20
Intelligence benchmarks for Claude Fable 5 and GPT-5.4 Nano
BenchmarkClaude Fable 5GPT-5.4 NanoLeader
AA Intelligence Index49.620.7Claude Fable 5
Epoch Capabilities Index163.4146.0Claude Fable 5
Agentic workLike-for-likePublic boards, shown as published, kept out of the index60
Agentic work benchmarks for Claude Fable 5 and GPT-5.4 Nano
BenchmarkClaude Fable 5GPT-5.4 NanoLeader
AA Agentic Index50.716.0Claude Fable 5
Design Arena: agents building web apps1261Not measuredOnly Claude Fable 5 measured
Design Arena: agents building full-stack apps1280Not measuredOnly Claude Fable 5 measured
Design Arena: agents building mobile apps1264Not measuredOnly Claude Fable 5 measured
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
LiveBench research86.9%Not measuredOnly Claude Fable 5 measured
LiveBench browser92.0%Not measuredOnly Claude Fable 5 measured
LiveBench long agentic53.2%Not measuredOnly Claude Fable 5 measured
Finance Agent (Vals AI)56.3%38.2%Claude Fable 5
Tax Agent Bench (Vals AI)38.3%5.0%Claude Fable 5
Legal Research Bench (Vals AI)49.5%6.3%Claude Fable 5
Excel Modeling Benchmark (Vals AI)73.7%44.8%Claude Fable 5
Terminal-Bench-Science (Vals AI)15.7%Not measuredOnly Claude Fable 5 measured
τ²-Bench Telecom98.5%76.0%Claude Fable 5
APEX-Agents63.6%Not measuredOnly Claude Fable 5 measured
Remote Labor Index16.1%Not measuredOnly Claude Fable 5 measured
PostTrainBench41.8%Not measuredOnly Claude Fable 5 measured
Vending-Bench 2$5,680Not measuredOnly Claude Fable 5 measured
LMArena Search1229Not measuredOnly Claude Fable 5 measured
Neither model has a result on the other 18 boards here
ReasoningLike-for-likePublic boards, shown as published, kept out of the index150
Reasoning benchmarks for Claude Fable 5 and GPT-5.4 Nano
BenchmarkClaude Fable 5GPT-5.4 NanoLeader
GPQA Diamond93.2%77.5%Claude Fable 5
LiveBench reasoning89.7%Not measuredOnly Claude Fable 5 measured
MMMU Pro (Vals AI)89.3%73.6%Claude Fable 5
GPQA Diamond (Artificial Analysis run)92.6%81.7%Claude Fable 5
Humanity's Last Exam (Artificial Analysis run)55.5%28.3%Claude Fable 5
GPQA Diamond (Epoch AI run)85.9%78.5%Claude Fable 5
ARC-AGI98.5%51.5%Claude Fable 5
ARC-AGI-289.2%5.7%Claude Fable 5
SimpleBench81.9%Not measuredOnly Claude Fable 5 measured
Chess puzzles47.0%45.0%Claude Fable 5
Mystery game puzzles52.0%9.0%Claude Fable 5
EBR-bench39.5%Not measuredOnly Claude Fable 5 measured
LMArena Text: hard prompts15071381Claude Fable 5
LMArena Text: expert15341396Claude Fable 5
LMArena Text: hard prompts in English15091387Claude Fable 5
LMArena Vision: diagrams13571210Claude Fable 5
LMArena Vision: homework13611225Claude Fable 5
Kagi LLM Benchmark91.4%39.7%Claude Fable 5
Neither model has a result on the other 4 boards here
MathLike-for-likePublic boards, shown as published, kept out of the index60
Math benchmarks for Claude Fable 5 and GPT-5.4 Nano
BenchmarkClaude Fable 5GPT-5.4 NanoLeader
AIMENot measured88.8%Only GPT-5.4 Nano measured
OTIS Mock AIME100.0%87.8%Claude Fable 5
FrontierMath, tiers 1 to 387.0%44.9%Claude Fable 5
FrontierMath, tier 490.2%12.2%Claude Fable 5
ProofBench95.0%5.0%Claude Fable 5
LMArena Text: math15161405Claude Fable 5
LMArena Text: mathematical work15151409Claude Fable 5
Neither model has a result on the other 6 boards here
KnowledgeLike-for-likePublic boards, shown as published, kept out of the index110
Knowledge benchmarks for Claude Fable 5 and GPT-5.4 Nano
BenchmarkClaude Fable 5GPT-5.4 NanoLeader
MMLU Pro91.5%77.2%Claude Fable 5
LegalBench (Vals AI)88.6%77.9%Claude Fable 5
CaseLaw (Vals AI)Not measured51.9%Only GPT-5.4 Nano measured
CorpFin (Vals AI)71.8%61.2%Claude Fable 5
TaxEval (Vals AI)76.9%67.4%Claude Fable 5
MortgageTax (Vals AI)68.9%59.1%Claude Fable 5
MedCode (Vals AI)56.1%41.0%Claude Fable 5
SimpleQA Verified70.7%11.7%Claude Fable 5
LMArena Text: science15061374Claude Fable 5
LMArena Text: medicine and healthcare14801369Claude Fable 5
LMArena Text: legal and government14981368Claude Fable 5
LMArena Text: business and finance14801366Claude Fable 5
Neither model has a result on the other 6 boards here
Web designDirectional onlyPublic boards, shown as published, kept out of the index9 boards, none shared
Web design benchmarks for Claude Fable 5 and GPT-5.4 Nano
BenchmarkClaude Fable 5GPT-5.4 NanoLeader
Design Arena: websites1295Not measuredOnly Claude Fable 5 measured
Design Arena: UI components1316Not measuredOnly Claude Fable 5 measured
Design Arena: game dev1335Not measuredOnly Claude Fable 5 measured
Design Arena: data viz1304Not measuredOnly Claude Fable 5 measured
Design Arena: 3D1318Not measuredOnly Claude Fable 5 measured
Design Arena: all code categories1310Not measuredOnly Claude Fable 5 measured
Design Arena: SVG1302Not measuredOnly Claude Fable 5 measured
Design Arena: ASCII art1329Not measuredOnly Claude Fable 5 measured
LiveBench design84.7%Not measuredOnly Claude Fable 5 measured
GeneralLike-for-likePublic boards, shown as published, kept out of the index291
General benchmarks for Claude Fable 5 and GPT-5.4 Nano
BenchmarkClaude Fable 5GPT-5.4 NanoLeader
LiveBench data analysis80.5%Not measuredOnly Claude Fable 5 measured
Public Benefits Bench (Vals AI)70.4%Not measuredOnly Claude Fable 5 measured
SAGE (Vals AI)51.9%38.1%Claude Fable 5
MedScribe (Vals AI)88.5%77.1%Claude Fable 5
Vals Multimodal Index74.2%47.6%Claude Fable 5
IFBench63.5%75.9%GPT-5.4 Nano
Long context reasoning (AA-LCR)82.3%76.7%Claude Fable 5
DTBench98.4%80.3%Claude Fable 5
LMCA61.2%36.9%Claude Fable 5
Surface Evolver Bench95.0%Not measuredOnly Claude Fable 5 measured
Furniture assembly35.8%Not measuredOnly Claude Fable 5 measured
LMArena Text14911372Claude Fable 5
LMArena Text: instruction following15021362Claude Fable 5
LMArena Text: creative writing14941315Claude Fable 5
LMArena Vision13251196Claude Fable 5
LMArena Text: English14981381Claude Fable 5
LMArena Text: non-English14821359Claude Fable 5
LMArena Text: Chinese15431391Claude Fable 5
LMArena Text: German14861368Claude Fable 5
LMArena Text: Japanese15041343Claude Fable 5
LMArena Text: Korean14871321Claude Fable 5
LMArena Text: French15051395Claude Fable 5
LMArena Text: Spanish14981371Claude Fable 5
LMArena Text: Russian15031363Claude Fable 5
LMArena Text: Polish14941366Claude Fable 5
LMArena Text: multi-turn15041382Claude Fable 5
LMArena Text: longer queries15101365Claude Fable 5
LMArena Text: writing and language15011338Claude Fable 5
LMArena Text: entertainment and media14821325Claude Fable 5
LMArena Vision: English13231202Claude Fable 5
LMArena Vision: Chinese13731232Claude Fable 5
LMArena Vision: reading text13371204Claude Fable 5
LMArena Vision: humor13411161Claude Fable 5
LMArena Vision: recognizing thingsNot measured1141Only GPT-5.4 Nano measured
LMArena Vision: creative writing13381159Claude 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 GPT-5.4 Nano
BenchmarkClaude Fable 5GPT-5.4 NanoLeader
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
GPT-5.4 Nano$0.0008Fits in one request

GPT-5.4 Nano costs less

Repository review

50K input + 3K output tokens

Claude Fable 5$0.650Fits in one request
GPT-5.4 Nano$0.014Fits in one request

GPT-5.4 Nano costs less

Agent loop

200K input + 10K output tokens

Claude Fable 5$2.50Fits in one request
GPT-5.4 Nano$0.052Fits in one request

GPT-5.4 Nano 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 GPT-5.4 Nano
SpecificationAnthropic Claude Fable 5OpenAI GPT-5.4 Nano
MakerAnthropicOpenAI
WeightsNo public weights listedNo public weights listed
ReleasedJune 9, 2026March 17, 2026
Context window1M400K
Input $/Mtok$10.00$0.20
Output $/Mtok$50.00$1.25
Coding index79.344.8
Independent measurements behind it62
Cost per solved task$2.16$0.14
SourceOpenRouter listingOpenRouter listing

Questions

Is Claude Fable 5 better than GPT-5.4 Nano for coding?

Pick Claude Fable 5 for coding: it scores 79.3 on the Vibe Coding Index against 44.8 for GPT-5.4 Nano. Pick GPT-5.4 Nano for output tokens 40.0x cheaper ($1.25 vs $50.00 per million) and a lower cost per solved task ($0.14 against $2.16).

Which is cheaper, Claude Fable 5 or GPT-5.4 Nano?

Claude Fable 5 costs $10.00 per million input tokens and $50.00 per million output tokens; GPT-5.4 Nano costs $0.20 and $1.25. Per solved SWE-bench Verified task, Claude Fable 5 costs $2.16 and GPT-5.4 Nano $0.14.

Which has the bigger context window, Claude Fable 5 or GPT-5.4 Nano?

Claude Fable 5, with 1M tokens against 400K.

How many benchmarks is the Claude Fable 5 vs GPT-5.4 Nano comparison based on?

82 benchmarks have a result for both models as of October 22, 2026. Claude Fable 5's coding index rests on 6 independent benchmarks and GPT-5.4 Nano's on 2. Where only one model has a result, the page says so instead of naming a winner.

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