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Claude Fable 5.1 vs GLM 5.3 Flash

Updated October 21, 2026. 97 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 GLM 5.3 Flash
Claude Fable 5.1Anthropic
Coding
89.1
Overall
53.4
Output $/M
$50.00
97
GLM 5.3 FlashZ.ai
Coding
71.0
Overall
41.8
Output $/M
$0.50
0
vs boards won of 97 shared

Decision reading

Pick Claude Fable 5.1 for coding: it scores 89.1 on the Vibe Coding Index against 71.0 for GLM 5.3 Flash.

Pick GLM 5.3 Flash when output tokens cost 100.0x less, or when the context window is larger, 1.05M against 1M tokens.

Model AClaude Fable 5.1Anthropic89.1/1002 independent benchmarksNo cost per solved taskModel BGLM 5.3 FlashZ.ai71.0/1002 independent benchmarks$0.02 per solved task
Shared results
97
Claude Fable 5.1 only
27
GLM 5.3 Flash only
5
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, GLM 5.3 Flash 71.0 from 2 benchmarks.
Widest category
Math, 33.7 points apart on average over 6 shared benchmarks.
Widest single gap
ProofBench: Claude Fable 5.1 100.0% against GLM 5.3 Flash 21.0%, 79.0 points apart on a 0 to 100 scale.
Output price
Claude Fable 5.1 $50.00 against GLM 5.3 Flash $0.50 per million output tokens, 100.0x apart.
Context window
Claude Fable 5.1 takes 1M tokens, GLM 5.3 Flash 1.05M.

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 5.1BarsGLM 5.3 FlashTies
Coding220
Intelligence20
Agentic work110
Reasoning140
Math60
Knowledge70
Web design90
General260
All shared boards970
CodingLike-for-likeFour of these boards feed the Vibe Coding Index220
Coding benchmarks for Claude Fable 5.1 and GLM 5.3 Flash
BenchmarkClaude Fable 5.1GLM 5.3 FlashLeader
LiveBench coding97.7%80.6%Claude Fable 5.1
LMArena WebDev17431607Claude Fable 5.1
AA Coding Index81.671.5Claude Fable 5.1
LiveCodeBench (Vals AI)90.5%80.5%Claude Fable 5.1
SWE-bench Verified (Vals AI)Not measured92.0%Only GLM 5.3 Flash measured
Terminal-Bench 4 (Vals AI)58.1%37.4%Claude Fable 5.1
Vibe Code Bench (Vals AI)90.3%30.8%Claude Fable 5.1
Code migration (Vals AI)54.6%20.5%Claude Fable 5.1
ProgramBench (Vals AI)7.0%0.0%Claude Fable 5.1
IOI (Vals AI)90.8%52.5%Claude Fable 5.1
Terminal-Bench 2.1 (Vals AI)85.0%62.9%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%16.0%Claude Fable 5.1
SkillsBench (Vals AI)61.5%40.2%Claude Fable 5.1
CyberBench (Vals AI)70.4%67.9%Claude Fable 5.1
SciCode63.1%51.6%Claude Fable 5.1
FrontierCode50.9%31.8%Claude Fable 5.1
FrontierSWE56.3%18.1%Claude Fable 5.1
GSO-Bench88.2%Not measuredOnly Claude Fable 5.1 measured
WeirdML92.9%Not measuredOnly Claude Fable 5.1 measured
MirrorCode73.3%Not measuredOnly Claude Fable 5.1 measured
ALE-Bench2143.2303.6Claude Fable 5.1
LMArena Text: coding15321507Claude Fable 5.1
LMArena Text: software and IT15301500Claude Fable 5.1
LMArena WebDev: React17921624Claude Fable 5.1
LMArena WebDev: HTML16841577Claude Fable 5.1
LMArena WebDev: from an image17221578Claude 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 GLM 5.3 Flash
BenchmarkClaude Fable 5.1GLM 5.3 FlashLeader
AA Intelligence Index53.441.8Claude Fable 5.1
Epoch Capabilities Index166.5153.1Claude Fable 5.1
Agentic workLike-for-likePublic boards, shown as published, kept out of the index110
Agentic work benchmarks for Claude Fable 5.1 and GLM 5.3 Flash
BenchmarkClaude Fable 5.1GLM 5.3 FlashLeader
AA Agentic Index57.950.9Claude Fable 5.1
Design Arena: agents building web apps1318Not measuredOnly Claude Fable 5.1 measured
Design Arena: agents building full-stack apps1326Not measuredOnly Claude Fable 5.1 measured
Design Arena: agents building mobile apps1267Not measuredOnly Claude Fable 5.1 measured
Design Arena: agents building Godot games1327Not measuredOnly Claude Fable 5.1 measured
Design Arena: PowerPoint slides1328Not measuredOnly Claude Fable 5.1 measured
Design Arena: spreadsheets1374Not measuredOnly Claude Fable 5.1 measured
LiveBench research82.0%70.1%Claude Fable 5.1
LiveBench browser100.0%84.0%Claude Fable 5.1
LiveBench long agentic80.8%28.4%Claude Fable 5.1
SREBench (Vals AI)22.9%0.8%Claude Fable 5.1
Finance Agent (Vals AI)58.9%57.9%Claude Fable 5.1
Tax Agent Bench (Vals AI)49.2%31.6%Claude Fable 5.1
Legal Research Bench (Vals AI)55.3%45.2%Claude Fable 5.1
Harvey's Legal Agent Benchmark (Vals AI)Not measured10.4%Only GLM 5.3 Flash measured
Excel Modeling Benchmark (Vals AI)76.7%55.9%Claude Fable 5.1
Terminal-Bench-Science (Vals AI)40.0%2.9%Claude Fable 5.1
Time Horizon Index (Vals AI)63.3%Not measuredOnly Claude Fable 5.1 measured
CUA-bench (Vals AI)13.2%Not measuredOnly Claude Fable 5.1 measured
Robo-bench (Vals AI)5.8%Not measuredOnly Claude Fable 5.1 measured
APEX-Agents68.6%52.8%Claude Fable 5.1
Remote Labor Index17.9%Not measuredOnly Claude Fable 5.1 measured
SpireClimb2.0%Not measuredOnly Claude Fable 5.1 measured
Vending-Bench 2$5,422Not measuredOnly Claude Fable 5.1 measured
LMArena Search1246Not measuredOnly Claude Fable 5.1 measured
Neither model has a result on the other 14 boards here
ReasoningLike-for-likePublic boards, shown as published, kept out of the index140
Reasoning benchmarks for Claude Fable 5.1 and GLM 5.3 Flash
BenchmarkClaude Fable 5.1GLM 5.3 FlashLeader
GPQA Diamond93.4%86.4%Claude Fable 5.1
LiveBench reasoning91.7%77.6%Claude Fable 5.1
MysteryMechanism (Vals AI)47.8%Not measuredOnly Claude Fable 5.1 measured
MMMU Pro (Vals AI)90.6%86.0%Claude Fable 5.1
GPQA Diamond (Artificial Analysis run)93.7%91.2%Claude Fable 5.1
Humanity's Last Exam (Artificial Analysis run)59.1%39.9%Claude Fable 5.1
GPQA Diamond (Epoch AI run)Not measured90.2%Only GLM 5.3 Flash measured
ARC-AGI97.5%91.0%Claude Fable 5.1
ARC-AGI-290.0%65.8%Claude Fable 5.1
Chess puzzles48.0%21.0%Claude Fable 5.1
Mystery game puzzles58.0%8.0%Claude Fable 5.1
EBR-bench57.1%Not measuredOnly Claude Fable 5.1 measured
LMArena Text: hard prompts15281490Claude Fable 5.1
LMArena Text: expert15441511Claude Fable 5.1
LMArena Text: hard prompts in English15221488Claude Fable 5.1
LMArena Vision: diagrams13431317Claude Fable 5.1
LMArena Vision: homework13451318Claude Fable 5.1
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 5.1 and GLM 5.3 Flash
BenchmarkClaude Fable 5.1GLM 5.3 FlashLeader
OTIS Mock AIME100.0%93.9%Claude Fable 5.1
FrontierMath, tiers 1 to 390.2%55.8%Claude Fable 5.1
FrontierMath, tier 487.8%17.1%Claude Fable 5.1
ProofBench100.0%21.0%Claude Fable 5.1
LMArena Text: math15311503Claude Fable 5.1
LMArena Text: mathematical work15411497Claude Fable 5.1
Neither model has a result on the other 7 boards here
KnowledgeLike-for-likePublic boards, shown as published, kept out of the index70
Knowledge benchmarks for Claude Fable 5.1 and GLM 5.3 Flash
BenchmarkClaude Fable 5.1GLM 5.3 FlashLeader
MMLU Pro92.4%86.1%Claude Fable 5.1
LegalBench (Vals AI)88.5%83.9%Claude Fable 5.1
TaxEval (Vals AI)76.0%75.6%Claude Fable 5.1
MortgageTax (Vals AI)70.8%Not measuredOnly Claude Fable 5.1 measured
MedCode (Vals AI)53.5%Not measuredOnly Claude Fable 5.1 measured
SimpleQA Verified70.8%Not measuredOnly Claude Fable 5.1 measured
LMArena Text: science15321484Claude Fable 5.1
LMArena Text: medicine and healthcare15311475Claude Fable 5.1
LMArena Text: legal and government15141473Claude Fable 5.1
LMArena Text: business and finance14931460Claude Fable 5.1
Neither model has a result on the other 7 boards here
Web designLike-for-likePublic boards, shown as published, kept out of the index90
Web design benchmarks for Claude Fable 5.1 and GLM 5.3 Flash
BenchmarkClaude Fable 5.1GLM 5.3 FlashLeader
Design Arena: websites13131272Claude Fable 5.1
Design Arena: UI components13381316Claude Fable 5.1
Design Arena: game dev13821279Claude Fable 5.1
Design Arena: data viz13441262Claude Fable 5.1
Design Arena: 3D13931316Claude Fable 5.1
Design Arena: all code categories13361282Claude Fable 5.1
Design Arena: SVG13011284Claude Fable 5.1
Design Arena: ASCII art13241269Claude Fable 5.1
LiveBench design83.4%77.2%Claude Fable 5.1
GeneralLike-for-likePublic boards, shown as published, kept out of the index260
General benchmarks for Claude Fable 5.1 and GLM 5.3 Flash
BenchmarkClaude Fable 5.1GLM 5.3 FlashLeader
Vals IndexNot measured50.9%Only GLM 5.3 Flash measured
LiveBench data analysis80.3%76.4%Claude Fable 5.1
Public Benefits Bench (Vals AI)74.9%Not measuredOnly Claude Fable 5.1 measured
SAGE (Vals AI)48.5%Not measuredOnly Claude Fable 5.1 measured
MedScribe (Vals AI)91.3%88.9%Claude Fable 5.1
Long context reasoning (AA-LCR)85.3%80.0%Claude Fable 5.1
DTBench97.6%Not measuredOnly Claude Fable 5.1 measured
LMCA65.5%Not measuredOnly Claude Fable 5.1 measured
Surface Evolver BenchNot measured52.5%Only GLM 5.3 Flash measured
Furniture assembly70.0%Not measuredOnly Claude Fable 5.1 measured
LMArena Text15121471Claude Fable 5.1
LMArena Text: instruction following15181478Claude Fable 5.1
LMArena Text: creative writing15091441Claude Fable 5.1
LMArena Vision13191294Claude Fable 5.1
LMArena Text: English15061474Claude Fable 5.1
LMArena Text: non-English15081462Claude Fable 5.1
LMArena Text: Chinese15841531Claude Fable 5.1
LMArena Text: German14991462Claude Fable 5.1
LMArena Text: Japanese15621444Claude Fable 5.1
LMArena Text: Korean15171436Claude Fable 5.1
LMArena Text: French15231491Claude Fable 5.1
LMArena Text: Spanish15201475Claude Fable 5.1
LMArena Text: Russian15201465Claude Fable 5.1
LMArena Text: Polish15251450Claude Fable 5.1
LMArena Text: multi-turn14931469Claude Fable 5.1
LMArena Text: longer queries15241481Claude Fable 5.1
LMArena Text: writing and language15101455Claude Fable 5.1
LMArena Text: entertainment and media14971440Claude Fable 5.1
LMArena Vision: English13131295Claude Fable 5.1
LMArena Vision: Chinese13911363Claude Fable 5.1
LMArena Vision: reading text13271299Claude Fable 5.1
LMArena Vision: humor13181279Claude Fable 5.1
LMArena Vision: creative writing13301270Claude Fable 5.1
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 GLM 5.3 Flash
BenchmarkClaude Fable 5.1GLM 5.3 FlashLeader
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
GLM 5.3 Flash$0.0004Fits in one request

GLM 5.3 Flash costs less

Repository review

50K input + 3K output tokens

Claude Fable 5.1$0.650Fits in one request
GLM 5.3 Flash$0.0090Fits in one request

GLM 5.3 Flash costs less

Agent loop

200K input + 10K output tokens

Claude Fable 5.1$2.50Fits in one request
GLM 5.3 Flash$0.035Fits in one request

GLM 5.3 Flash 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 GLM 5.3 Flash
SpecificationAnthropic Claude Fable 5.1Z.ai GLM 5.3 Flash
MakerAnthropicZ.ai
WeightsNo public weights listedOpen weights
ReleasedSeptember 1, 2026August 26, 2026
Context window1M1.05M
Input $/Mtok$10.00$0.15
Output $/Mtok$50.00$0.50
Coding index89.171.0
Independent measurements behind it22
Cost per solved taskNot computable$0.02
SourceOpenRouter listingOpenRouter listing

Questions

Is Claude Fable 5.1 better than GLM 5.3 Flash for coding?

Pick Claude Fable 5.1 for coding: it scores 89.1 on the Vibe Coding Index against 71.0 for GLM 5.3 Flash. Pick GLM 5.3 Flash when output tokens cost 100.0x less, or when the context window is larger, 1.05M against 1M tokens.

Which is cheaper, Claude Fable 5.1 or GLM 5.3 Flash?

Claude Fable 5.1 costs $10.00 per million input tokens and $50.00 per million output tokens; GLM 5.3 Flash costs $0.15 and $0.50. Cost per solved task is known for GLM 5.3 Flash only.

Which has the bigger context window, Claude Fable 5.1 or GLM 5.3 Flash?

GLM 5.3 Flash, with 1.05M tokens against 1M.

How many benchmarks is the Claude Fable 5.1 vs GLM 5.3 Flash comparison based on?

97 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 GLM 5.3 Flash's on 2. Where only one model has a result, the page says so instead of naming a winner.

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