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Claude Fable 5 vs GLM 5.3 Flash

Claude Fable 5 leads GLM 5.3 Flash on coding, 79.3 to 57.7 on the Vibe Coding Index, and GLM 5.3 Flash costs 100.0x less per output token ($0.50 vs $50.00 per million). Updated October 22, 2026; 95 benchmarks have a result for both.

Replace Claude Fable 5 Replace GLM 5.3 Flash
Claude Fable 5Anthropic
Coding
79.3
Overall
79.0
Output $/M
$50.00
90
GLM 5.3 FlashZ.ai
Coding
57.7
Overall
66.0
Output $/M
$0.50
4
vs boards won of 95 shared, 1 tied

Claude Fable 5 or GLM 5.3 Flash: which to pick

Pick Claude Fable 5 for coding: it scores 79.3 on the Vibe Coding Index against 57.7 for GLM 5.3 Flash.

Pick GLM 5.3 Flash for output tokens 100.0x cheaper ($0.50 vs $50.00 per million) and a lower cost per solved task ($0.02 against $2.16).

Model AClaude Fable 5Anthropic79.3/1006 independent benchmarks$2.16 per solved taskModel BGLM 5.3 FlashZ.ai57.7/1006 independent benchmarks$0.02 per solved task
Shared results
95
Claude Fable 5 only
32
GLM 5.3 Flash only
7
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, GLM 5.3 Flash 57.7 from 6 benchmarks.
Widest category
Math, 31.6 points apart on average over 6 shared benchmarks.
Widest single gap
ProofBench: Claude Fable 5 95.0% against GLM 5.3 Flash 21.0%, 74.0 points apart on a 0 to 100 scale.
Output price
Claude Fable 5 $50.00 against GLM 5.3 Flash $0.50 per million output tokens, 100.0x apart.
Context window
Claude Fable 5 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 5BarsGLM 5.3 FlashTies
Coding190
Intelligence20
Agentic work82
Reasoning141
Math60
Knowledge70
Web design801 tie
General261
All shared boards9041 tie
CodingLike-for-likeSix of these boards feed the Vibe Coding Index190
Coding benchmarks for Claude Fable 5 and GLM 5.3 Flash
BenchmarkClaude Fable 5GLM 5.3 FlashLeader
LiveBench coding98.3%80.6%Claude Fable 5
LMArena WebDev16241607Claude Fable 5
AA Coding Index76.571.5Claude Fable 5
LiveCodeBench (Vals AI)89.8%80.5%Claude Fable 5
SWE-bench Verified (Vals AI)95.0%92.0%Claude Fable 5
Terminal-Bench 4 (Vals AI)41.4%37.4%Claude Fable 5
Vibe Code Bench (Vals AI)90.3%30.8%Claude Fable 5
Code migration (Vals AI)55.1%20.5%Claude Fable 5
ProgramBench (Vals AI)2.0%0.0%Claude Fable 5
IOI (Vals AI)Not measured52.5%Only GLM 5.3 Flash measured
Terminal-Bench 2.1 (Vals AI)80.5%62.9%Claude Fable 5
Vibe Code Bench 1-100 (Vals AI)Not measured16.0%Only GLM 5.3 Flash measured
SkillsBench (Vals AI)Not measured40.2%Only GLM 5.3 Flash measured
CyberBench (Vals AI)Not measured67.9%Only GLM 5.3 Flash measured
SciCode61.0%51.6%Claude Fable 5
Terminal-Bench Hard (Artificial Analysis run)62.9%Not measuredOnly Claude Fable 5 measured
FrontierCode53.5%31.8%Claude Fable 5
FrontierSWE47.0%18.1%Claude Fable 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-Bench2041.3303.6Claude Fable 5
LMArena Text: coding15181507Claude Fable 5
LMArena Text: software and IT15131500Claude Fable 5
LMArena WebDev: React16311624Claude Fable 5
LMArena WebDev: HTML16511577Claude Fable 5
LMArena WebDev: from an image16231578Claude Fable 5
Neither model has a result on the other 12 boards here
IntelligenceLike-for-likePublic boards, shown as published, kept out of the index20
Intelligence benchmarks for Claude Fable 5 and GLM 5.3 Flash
BenchmarkClaude Fable 5GLM 5.3 FlashLeader
AA Intelligence Index49.641.8Claude Fable 5
Epoch Capabilities Index163.4153.1Claude Fable 5
Agentic workLike-for-likePublic boards, shown as published, kept out of the index82
Agentic work benchmarks for Claude Fable 5 and GLM 5.3 Flash
BenchmarkClaude Fable 5GLM 5.3 FlashLeader
AA Agentic Index50.750.9GLM 5.3 Flash
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%70.1%Claude Fable 5
LiveBench browser92.0%84.0%Claude Fable 5
LiveBench long agentic53.2%28.4%Claude Fable 5
SREBench (Vals AI)Not measured0.8%Only GLM 5.3 Flash measured
Finance Agent (Vals AI)56.3%57.9%GLM 5.3 Flash
Tax Agent Bench (Vals AI)38.3%31.6%Claude Fable 5
Legal Research Bench (Vals AI)49.5%45.2%Claude Fable 5
Harvey's Legal Agent Benchmark (Vals AI)Not measured10.4%Only GLM 5.3 Flash measured
Excel Modeling Benchmark (Vals AI)73.7%55.9%Claude Fable 5
Terminal-Bench-Science (Vals AI)15.7%2.9%Claude Fable 5
τ²-Bench Telecom98.5%Not measuredOnly Claude Fable 5 measured
APEX-Agents63.6%52.8%Claude Fable 5
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 16 boards here
ReasoningLike-for-likePublic boards, shown as published, kept out of the index141
Reasoning benchmarks for Claude Fable 5 and GLM 5.3 Flash
BenchmarkClaude Fable 5GLM 5.3 FlashLeader
GPQA Diamond93.2%86.4%Claude Fable 5
LiveBench reasoning89.7%77.6%Claude Fable 5
MMMU Pro (Vals AI)89.3%86.0%Claude Fable 5
GPQA Diamond (Artificial Analysis run)92.6%91.2%Claude Fable 5
Humanity's Last Exam (Artificial Analysis run)55.5%39.9%Claude Fable 5
GPQA Diamond (Epoch AI run)85.9%90.2%GLM 5.3 Flash
ARC-AGI98.5%91.0%Claude Fable 5
ARC-AGI-289.2%65.8%Claude Fable 5
SimpleBench81.9%Not measuredOnly Claude Fable 5 measured
Chess puzzles47.0%21.0%Claude Fable 5
Mystery game puzzles52.0%8.0%Claude Fable 5
EBR-bench39.5%Not measuredOnly Claude Fable 5 measured
LMArena Text: hard prompts15071490Claude Fable 5
LMArena Text: expert15341511Claude Fable 5
LMArena Text: hard prompts in English15091488Claude Fable 5
LMArena Vision: diagrams13571317Claude Fable 5
LMArena Vision: homework13611318Claude Fable 5
Kagi LLM Benchmark91.4%Not measuredOnly Claude Fable 5 measured
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 GLM 5.3 Flash
BenchmarkClaude Fable 5GLM 5.3 FlashLeader
OTIS Mock AIME100.0%93.9%Claude Fable 5
FrontierMath, tiers 1 to 387.0%55.8%Claude Fable 5
FrontierMath, tier 490.2%17.1%Claude Fable 5
ProofBench95.0%21.0%Claude Fable 5
LMArena Text: math15161503Claude Fable 5
LMArena Text: mathematical work15151497Claude Fable 5
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 and GLM 5.3 Flash
BenchmarkClaude Fable 5GLM 5.3 FlashLeader
MMLU Pro91.5%86.1%Claude Fable 5
LegalBench (Vals AI)88.6%83.9%Claude Fable 5
CorpFin (Vals AI)71.8%Not measuredOnly Claude Fable 5 measured
TaxEval (Vals AI)76.9%75.6%Claude Fable 5
MortgageTax (Vals AI)68.9%Not measuredOnly Claude Fable 5 measured
MedCode (Vals AI)56.1%Not measuredOnly Claude Fable 5 measured
SimpleQA Verified70.7%Not measuredOnly Claude Fable 5 measured
LMArena Text: science15061484Claude Fable 5
LMArena Text: medicine and healthcare14801475Claude Fable 5
LMArena Text: legal and government14981473Claude Fable 5
LMArena Text: business and finance14801460Claude 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 index80
Web design benchmarks for Claude Fable 5 and GLM 5.3 Flash
BenchmarkClaude Fable 5GLM 5.3 FlashLeader
Design Arena: websites12951272Claude Fable 5
Design Arena: UI components13161316Tie
Design Arena: game dev13351278Claude Fable 5
Design Arena: data viz13041262Claude Fable 5
Design Arena: 3D13181316Claude Fable 5
Design Arena: all code categories13101282Claude Fable 5
Design Arena: SVG13021285Claude Fable 5
Design Arena: ASCII art13291267Claude Fable 5
LiveBench design84.7%77.2%Claude Fable 5
GeneralLike-for-likePublic boards, shown as published, kept out of the index261
General benchmarks for Claude Fable 5 and GLM 5.3 Flash
BenchmarkClaude Fable 5GLM 5.3 FlashLeader
Vals IndexNot measured50.9%Only GLM 5.3 Flash measured
LiveBench data analysis80.5%76.4%Claude Fable 5
Public Benefits Bench (Vals AI)70.4%Not measuredOnly Claude Fable 5 measured
SAGE (Vals AI)51.9%Not measuredOnly Claude Fable 5 measured
MedScribe (Vals AI)88.5%88.9%GLM 5.3 Flash
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%80.0%Claude Fable 5
DTBench98.4%Not measuredOnly Claude Fable 5 measured
LMCA61.2%Not measuredOnly Claude Fable 5 measured
Surface Evolver Bench95.0%52.5%Claude Fable 5
Furniture assembly35.8%Not measuredOnly Claude Fable 5 measured
LMArena Text14911471Claude Fable 5
LMArena Text: instruction following15021478Claude Fable 5
LMArena Text: creative writing14941441Claude Fable 5
LMArena Vision13251294Claude Fable 5
LMArena Text: English14981474Claude Fable 5
LMArena Text: non-English14821462Claude Fable 5
LMArena Text: Chinese15431531Claude Fable 5
LMArena Text: German14861462Claude Fable 5
LMArena Text: Japanese15041444Claude Fable 5
LMArena Text: Korean14871436Claude Fable 5
LMArena Text: French15051491Claude Fable 5
LMArena Text: Spanish14981475Claude Fable 5
LMArena Text: Russian15031465Claude Fable 5
LMArena Text: Polish14941450Claude Fable 5
LMArena Text: multi-turn15041469Claude Fable 5
LMArena Text: longer queries15101481Claude Fable 5
LMArena Text: writing and language15011455Claude Fable 5
LMArena Text: entertainment and media14821440Claude Fable 5
LMArena Vision: English13231295Claude Fable 5
LMArena Vision: Chinese13731363Claude Fable 5
LMArena Vision: reading text13371299Claude Fable 5
LMArena Vision: humor13411279Claude Fable 5
LMArena Vision: creative writing13381270Claude 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 GLM 5.3 Flash
BenchmarkClaude Fable 5GLM 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$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$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$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 and GLM 5.3 Flash
SpecificationAnthropic Claude Fable 5Z.ai GLM 5.3 Flash
MakerAnthropicZ.ai
WeightsNo public weights listedOpen weights
ReleasedJune 9, 2026August 26, 2026
Context window1M1.05M
Input $/Mtok$10.00$0.15
Output $/Mtok$50.00$0.50
Coding index79.357.7
Independent measurements behind it66
Cost per solved task$2.16$0.02
SourceOpenRouter listingOpenRouter listing

Questions

Is Claude Fable 5 better than GLM 5.3 Flash for coding?

Pick Claude Fable 5 for coding: it scores 79.3 on the Vibe Coding Index against 57.7 for GLM 5.3 Flash. Pick GLM 5.3 Flash for output tokens 100.0x cheaper ($0.50 vs $50.00 per million) and a lower cost per solved task ($0.02 against $2.16).

Which is cheaper, Claude Fable 5 or GLM 5.3 Flash?

Claude Fable 5 costs $10.00 per million input tokens and $50.00 per million output tokens; GLM 5.3 Flash costs $0.15 and $0.50. Per solved SWE-bench Verified task, Claude Fable 5 costs $2.16 and GLM 5.3 Flash $0.02.

Which has the bigger context window, Claude Fable 5 or GLM 5.3 Flash?

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

How many benchmarks is the Claude Fable 5 vs GLM 5.3 Flash comparison based on?

95 benchmarks have a result for both models as of October 22, 2026. Claude Fable 5's coding index rests on 6 independent benchmarks and GLM 5.3 Flash's on 6. Where only one model has a result, the page says so instead of naming a winner.

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