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Claude Opus 5.5 vs GLM 5.3 Flash

Claude Opus 5.5 leads GLM 5.3 Flash on coding, 88.8 to 57.7 on the Vibe Coding Index, and GLM 5.3 Flash costs 40.0x less per output token ($0.50 vs $20.00 per million). Updated October 21, 2026; 84 benchmarks have a result for both.

Replace Claude Opus 5.5 Replace GLM 5.3 Flash
Claude Opus 5.5Anthropic
Coding
88.8
Overall
87.1
Output $/M
$20.00
82
GLM 5.3 FlashZ.ai
Coding
57.7
Overall
66.0
Output $/M
$0.50
2
vs boards won of 84 shared

Claude Opus 5.5 or GLM 5.3 Flash: which to pick

Pick Claude Opus 5.5 for coding: it scores 88.8 on the Vibe Coding Index against 57.7 for GLM 5.3 Flash, though on 5 benchmarks against 6.

Pick GLM 5.3 Flash for output tokens 40.0x cheaper ($0.50 vs $20.00 per million) and a larger context window (1.05M against 1M tokens).

Model AClaude Opus 5.5Anthropic88.8/1005 independent benchmarksNo cost per solved taskModel BGLM 5.3 FlashZ.ai57.7/1006 independent benchmarks$0.02 per solved task
Shared results
84
Claude Opus 5.5 only
25
GLM 5.3 Flash only
18
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 Opus 5.5 88.8 from 5 benchmarks, GLM 5.3 Flash 57.7 from 6 benchmarks.
Widest category
Math, 34.0 points apart on average over 6 shared benchmarks.
Widest single gap
ProofBench: Claude Opus 5.5 100.0% against GLM 5.3 Flash 21.0%, 79.0 points apart on a 0 to 100 scale.
Output price
Claude Opus 5.5 $20.00 against GLM 5.3 Flash $0.50 per million output tokens, 40.0x apart.
Context window
Claude Opus 5.5 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 Opus 5.5BarsGLM 5.3 FlashTies
Coding190
Intelligence20
Agentic work92
Reasoning120
Math60
Knowledge40
Web design80
General220
All shared boards822
CodingLike-for-likeSix of these boards feed the Vibe Coding Index190
Coding benchmarks for Claude Opus 5.5 and GLM 5.3 Flash
BenchmarkClaude Opus 5.5GLM 5.3 FlashLeader
LiveBench coding96.3%80.6%Claude Opus 5.5
LMArena WebDev18071607Claude Opus 5.5
AA Coding IndexNot measured71.5Only GLM 5.3 Flash measured
LiveCodeBench (Vals AI)Not measured80.5%Only GLM 5.3 Flash measured
SWE-bench Verified (Vals AI)Not measured92.0%Only GLM 5.3 Flash measured
Terminal-Bench 4 (Vals AI)65.2%37.4%Claude Opus 5.5
Vibe Code Bench (Vals AI)90.3%30.8%Claude Opus 5.5
Code migration (Vals AI)66.7%20.5%Claude Opus 5.5
ProgramBench (Vals AI)18.5%0.0%Claude Opus 5.5
IOI (Vals AI)95.1%52.5%Claude Opus 5.5
Terminal-Bench 2.1 (Vals AI)87.6%62.9%Claude Opus 5.5
SWE-bench Multimodal (Vals AI)70.2%Not measuredOnly Claude Opus 5.5 measured
Vibe Code Bench 1-100 (Vals AI)30.4%16.0%Claude Opus 5.5
SkillsBench (Vals AI)Not measured40.2%Only GLM 5.3 Flash measured
CyberBench (Vals AI)74.6%67.9%Claude Opus 5.5
SciCode66.9%51.6%Claude Opus 5.5
FrontierCode54.6%31.8%Claude Opus 5.5
FrontierSWE62.3%18.1%Claude Opus 5.5
MirrorCode77.4%Not measuredOnly Claude Opus 5.5 measured
ALE-Bench2147.4303.6Claude Opus 5.5
LMArena Text: coding15451507Claude Opus 5.5
LMArena Text: software and IT15381500Claude Opus 5.5
LMArena WebDev: React18551624Claude Opus 5.5
LMArena WebDev: HTML17531577Claude Opus 5.5
LMArena WebDev: from an image17531578Claude Opus 5.5
SciCode18.5%Not measuredOnly Claude Opus 5.5 measured
Neither model has a result on the other 13 boards here
IntelligenceLike-for-likePublic boards, shown as published, kept out of the index20
Intelligence benchmarks for Claude Opus 5.5 and GLM 5.3 Flash
BenchmarkClaude Opus 5.5GLM 5.3 FlashLeader
AA Intelligence Index57.641.8Claude Opus 5.5
Epoch Capabilities Index168.8153.1Claude Opus 5.5
Agentic workLike-for-likePublic boards, shown as published, kept out of the index92
Agentic work benchmarks for Claude Opus 5.5 and GLM 5.3 Flash
BenchmarkClaude Opus 5.5GLM 5.3 FlashLeader
AA Agentic IndexNot measured50.9Only GLM 5.3 Flash measured
Design Arena: agents building web apps1317Not measuredOnly Claude Opus 5.5 measured
Design Arena: agents building mobile apps1310Not measuredOnly Claude Opus 5.5 measured
Design Arena: spreadsheets1352Not measuredOnly Claude Opus 5.5 measured
LiveBench research85.0%70.1%Claude Opus 5.5
LiveBench browser80.0%84.0%GLM 5.3 Flash
LiveBench long agentic85.0%28.4%Claude Opus 5.5
SREBench (Vals AI)33.6%0.8%Claude Opus 5.5
Finance Agent (Vals AI)58.6%57.9%Claude Opus 5.5
Tax Agent Bench (Vals AI)45.6%31.6%Claude Opus 5.5
Legal Research Bench (Vals AI)50.5%45.2%Claude Opus 5.5
Harvey's Legal Agent Benchmark (Vals AI)9.2%10.4%GLM 5.3 Flash
Excel Modeling Benchmark (Vals AI)75.9%55.9%Claude Opus 5.5
BioMysteryBench (Vals AI)79.3%Not measuredOnly Claude Opus 5.5 measured
Terminal-Bench-Science (Vals AI)47.1%2.9%Claude Opus 5.5
Vals Science Index58.7%Not measuredOnly Claude Opus 5.5 measured
Time Horizon Index (Vals AI)91.3%Not measuredOnly Claude Opus 5.5 measured
CUA-bench (Vals AI)14.0%Not measuredOnly Claude Opus 5.5 measured
Robo-bench (Vals AI)14.6%Not measuredOnly Claude Opus 5.5 measured
APEX-Agents73.5%52.8%Claude Opus 5.5
Remote Labor Index21.3%Not measuredOnly Claude Opus 5.5 measured
SpireClimb3.3%Not measuredOnly Claude Opus 5.5 measured
Vending-Bench 2$9,235Not measuredOnly Claude Opus 5.5 measured
LMArena Search1213Not measuredOnly Claude Opus 5.5 measured
Neither model has a result on the other 17 boards here
ReasoningLike-for-likePublic boards, shown as published, kept out of the index120
Reasoning benchmarks for Claude Opus 5.5 and GLM 5.3 Flash
BenchmarkClaude Opus 5.5GLM 5.3 FlashLeader
GPQA DiamondNot measured86.4%Only GLM 5.3 Flash measured
LiveBench reasoning92.2%77.6%Claude Opus 5.5
MysteryMechanism (Vals AI)49.5%Not measuredOnly Claude Opus 5.5 measured
MMMU Pro (Vals AI)Not measured86.0%Only GLM 5.3 Flash measured
GPQA Diamond (Artificial Analysis run)Not measured91.2%Only GLM 5.3 Flash measured
Humanity's Last Exam (Artificial Analysis run)61.4%39.9%Claude Opus 5.5
GPQA Diamond (Epoch AI run)90.6%90.2%Claude Opus 5.5
ARC-AGI98.5%91.0%Claude Opus 5.5
ARC-AGI-293.3%65.8%Claude Opus 5.5
Chess puzzles67.0%21.0%Claude Opus 5.5
Mystery game puzzles71.0%8.0%Claude Opus 5.5
EBR-bench71.4%Not measuredOnly Claude Opus 5.5 measured
LMArena Text: hard prompts15361490Claude Opus 5.5
LMArena Text: expert15491511Claude Opus 5.5
LMArena Text: hard prompts in English15351488Claude Opus 5.5
LMArena Vision: diagrams13451317Claude Opus 5.5
LMArena Vision: homework13621318Claude Opus 5.5
Neither model has a result on the other 5 boards here
MathLike-for-likePublic boards, shown as published, kept out of the index60
Math benchmarks for Claude Opus 5.5 and GLM 5.3 Flash
BenchmarkClaude Opus 5.5GLM 5.3 FlashLeader
OTIS Mock AIME100.0%93.9%Claude Opus 5.5
FrontierMath, tiers 1 to 391.2%55.8%Claude Opus 5.5
FrontierMath, tier 495.0%17.1%Claude Opus 5.5
ProofBench100.0%21.0%Claude Opus 5.5
LMArena Text: math15181503Claude Opus 5.5
LMArena Text: mathematical work15161497Claude Opus 5.5
Neither model has a result on the other 7 boards here
KnowledgeLike-for-likePublic boards, shown as published, kept out of the index40
Knowledge benchmarks for Claude Opus 5.5 and GLM 5.3 Flash
BenchmarkClaude Opus 5.5GLM 5.3 FlashLeader
MMLU ProNot measured86.1%Only GLM 5.3 Flash measured
LegalBench (Vals AI)Not measured83.9%Only GLM 5.3 Flash measured
TaxEval (Vals AI)Not measured75.6%Only GLM 5.3 Flash measured
MedCode (Vals AI)49.8%Not measuredOnly Claude Opus 5.5 measured
SimpleQA Verified72.2%Not measuredOnly Claude Opus 5.5 measured
LMArena Text: science15241484Claude Opus 5.5
LMArena Text: medicine and healthcare15091475Claude Opus 5.5
LMArena Text: legal and government15181473Claude Opus 5.5
LMArena Text: business and finance14941460Claude Opus 5.5
FACTS Benchmark Suite65.3%Not measuredOnly Claude Opus 5.5 measured
Neither model has a result on the other 8 boards here
Web designLike-for-likePublic boards, shown as published, kept out of the index80
Web design benchmarks for Claude Opus 5.5 and GLM 5.3 Flash
BenchmarkClaude Opus 5.5GLM 5.3 FlashLeader
Design Arena: websites13361272Claude Opus 5.5
Design Arena: UI components13921316Claude Opus 5.5
Design Arena: game dev14581278Claude Opus 5.5
Design Arena: data viz13971261Claude Opus 5.5
Design Arena: 3D14771316Claude Opus 5.5
Design Arena: all code categories13901282Claude Opus 5.5
Design Arena: SVG13331284Claude Opus 5.5
Design Arena: ASCII artNot measured1268Only GLM 5.3 Flash measured
LiveBench design86.9%77.2%Claude Opus 5.5
GeneralLike-for-likePublic boards, shown as published, kept out of the index220
General benchmarks for Claude Opus 5.5 and GLM 5.3 Flash
BenchmarkClaude Opus 5.5GLM 5.3 FlashLeader
Vals Index70.2%50.9%Claude Opus 5.5
LiveBench data analysis80.3%76.4%Claude Opus 5.5
Public Benefits Bench (Vals AI)70.6%Not measuredOnly Claude Opus 5.5 measured
SAGE (Vals AI)45.8%Not measuredOnly Claude Opus 5.5 measured
MedScribe (Vals AI)91.4%88.9%Claude Opus 5.5
Long context reasoning (AA-LCR)84.7%80.0%Claude Opus 5.5
DTBench98.9%Not measuredOnly Claude Opus 5.5 measured
LMCA68.2%Not measuredOnly Claude Opus 5.5 measured
Surface Evolver BenchNot measured52.5%Only GLM 5.3 Flash measured
Furniture assembly83.3%Not measuredOnly Claude Opus 5.5 measured
LMArena Text15161471Claude Opus 5.5
LMArena Text: instruction following15371478Claude Opus 5.5
LMArena Text: creative writing15351441Claude Opus 5.5
LMArena Vision13211294Claude Opus 5.5
LMArena Text: English15191474Claude Opus 5.5
LMArena Text: non-English15071462Claude Opus 5.5
LMArena Text: Chinese15821531Claude Opus 5.5
LMArena Text: GermanNot measured1462Only GLM 5.3 Flash measured
LMArena Text: Japanese15341444Claude Opus 5.5
LMArena Text: KoreanNot measured1436Only GLM 5.3 Flash measured
LMArena Text: French14931491Claude Opus 5.5
LMArena Text: Spanish15081475Claude Opus 5.5
LMArena Text: Russian15171465Claude Opus 5.5
LMArena Text: PolishNot measured1450Only GLM 5.3 Flash measured
LMArena Text: multi-turn15011469Claude Opus 5.5
LMArena Text: longer queries15321481Claude Opus 5.5
LMArena Text: writing and language15321455Claude Opus 5.5
LMArena Text: entertainment and media15151440Claude Opus 5.5
LMArena Vision: English13171295Claude Opus 5.5
LMArena Vision: ChineseNot measured1363Only GLM 5.3 Flash measured
LMArena Vision: reading text13261299Claude Opus 5.5
LMArena Vision: humorNot measured1279Only GLM 5.3 Flash measured
LMArena Vision: creative writing13201270Claude Opus 5.5
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 Opus 5.5 and GLM 5.3 Flash
BenchmarkClaude Opus 5.5GLM 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 Opus 5.5$0.014Fits 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 Opus 5.5$0.260Fits 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 Opus 5.5$1.00Fits 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 Opus 5.5 and GLM 5.3 Flash
SpecificationAnthropic Claude Opus 5.5Z.ai GLM 5.3 Flash
MakerAnthropicZ.ai
WeightsNo public weights listedOpen weights
ReleasedSeptember 22, 2026August 26, 2026
Context window1M1.05M
Input $/Mtok$4.00$0.15
Output $/Mtok$20.00$0.50
Coding index88.857.7
Independent measurements behind it56
Cost per solved taskNot computable$0.02
SourceOpenRouter listingOpenRouter listing

Questions

Is Claude Opus 5.5 better than GLM 5.3 Flash for coding?

Pick Claude Opus 5.5 for coding: it scores 88.8 on the Vibe Coding Index against 57.7 for GLM 5.3 Flash, though on 5 benchmarks against 6. Pick GLM 5.3 Flash for output tokens 40.0x cheaper ($0.50 vs $20.00 per million) and a larger context window (1.05M against 1M tokens).

Which is cheaper, Claude Opus 5.5 or GLM 5.3 Flash?

Claude Opus 5.5 costs $4.00 per million input tokens and $20.00 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 Opus 5.5 or GLM 5.3 Flash?

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

How many benchmarks is the Claude Opus 5.5 vs GLM 5.3 Flash comparison based on?

84 benchmarks have a result for both models as of October 21, 2026. Claude Opus 5.5's coding index rests on 5 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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