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GLM 5.1 vs GPT-5.5

Updated October 21, 2026. 87 benchmarks have a result for both. Coding is ranked on the Vibe Coding Index; every other board is shown as published.

Replace GLM 5.1 Replace GPT-5.5
GLM 5.1Z.ai
Coding
44.0
Overall
26.1
Output $/M
$4.40
18
GPT-5.5OpenAI
Coding
67.8
Overall
38.4
Output $/M
$30.00
69
vs boards won of 87 shared

Decision reading

Pick GPT-5.5 for coding: it scores 67.8 on the Vibe Coding Index against 44.0 for GLM 5.1.

Pick GLM 5.1 when output tokens cost 6.8x less, or when a solved task costs $0.60 against $1.65.

Model AGLM 5.1Z.ai44.0/1001 independent benchmark$0.60 per solved taskModel BGPT-5.5OpenAI67.8/1002 independent benchmarks$1.65 per solved task
Shared results
87
GLM 5.1 only
2
GPT-5.5 only
45
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
GLM 5.1 44.0 from 1 benchmark, GPT-5.5 67.8 from 2 benchmarks.
Widest category
Math, 18.3 points apart on average over 5 shared benchmarks.
Widest single gap
FrontierMath, tiers 1 to 3: GLM 5.1 36.8% against GPT-5.5 85.3%, 48.4 points apart on a 0 to 100 scale.
Output price
GLM 5.1 $4.40 against GPT-5.5 $30.00 per million output tokens, 6.8x apart.
Context window
GLM 5.1 takes 205K tokens, GPT-5.5 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
CategoryGLM 5.1BarsGPT-5.5Ties
Coding016
Intelligence02
Agentic work77
Reasoning09
Math14
Knowledge110
Web design53
General418
All shared boards1869
CodingLike-for-likeFour of these boards feed the Vibe Coding Index016
Coding benchmarks for GLM 5.1 and GPT-5.5
BenchmarkGLM 5.1GPT-5.5Leader
LiveBench codingNot measured85.1%Only GPT-5.5 measured
LMArena WebDev15081513GPT-5.5
AA Coding Index55.874.9GPT-5.5
LiveCodeBench (Vals AI)81.4%85.3%GPT-5.5
SWE-bench Verified (Vals AI)76.4%82.6%GPT-5.5
Vibe Code Bench (Vals AI)31.5%69.8%GPT-5.5
Code migration (Vals AI)25.8%45.2%GPT-5.5
ProgramBench (Vals AI)0.0%0.5%GPT-5.5
Terminal-Bench 2.1 (Vals AI)56.9%76.4%GPT-5.5
SkillsBench (Vals AI)Not measured62.5%Only GPT-5.5 measured
SciCode44.8%56.1%GPT-5.5
Terminal-Bench Hard (Artificial Analysis run)43.2%60.6%GPT-5.5
Terminal-BenchNot measured84.7%Only GPT-5.5 measured
FrontierCodeNot measured43.0%Only GPT-5.5 measured
GSO-BenchNot measured40.2%Only GPT-5.5 measured
WeirdML57.1%84.9%GPT-5.5
MirrorCodeNot measured10.0%Only GPT-5.5 measured
ALE-Bench887.11943.0GPT-5.5
LMArena Text: coding14851494GPT-5.5
LMArena Text: software and IT14841493GPT-5.5
LMArena WebDev: React15051506GPT-5.5
LMArena WebDev: HTML15081543GPT-5.5
LMArena WebDev: from an imageNot measured1532Only GPT-5.5 measured
Neither model has a result on the other 15 boards here
IntelligenceLike-for-likePublic boards, shown as published, kept out of the index02
Intelligence benchmarks for GLM 5.1 and GPT-5.5
BenchmarkGLM 5.1GPT-5.5Leader
AA Intelligence Index26.138.4GPT-5.5
Epoch Capabilities Index149.8159.7GPT-5.5
Agentic workLike-for-likePublic boards, shown as published, kept out of the index77
Agentic work benchmarks for GLM 5.1 and GPT-5.5
BenchmarkGLM 5.1GPT-5.5Leader
AA Agentic Index23.936.4GPT-5.5
Design Arena: agents building web apps11751117GLM 5.1
Design Arena: agents building full-stack apps11671089GLM 5.1
Design Arena: agents building mobile apps11621143GLM 5.1
Design Arena: agents building Android apps11861169GLM 5.1
Design Arena: agents building Godot games10531173GPT-5.5
Design Arena: agents building games11641179GPT-5.5
Design Arena: HTML slides11701067GLM 5.1
Design Arena: PowerPoint slides11891108GLM 5.1
Design Arena: spreadsheets1315Not measuredOnly GLM 5.1 measured
LiveBench researchNot measured61.6%Only GPT-5.5 measured
LiveBench browserNot measured48.0%Only GPT-5.5 measured
LiveBench long agenticNot measured44.6%Only GPT-5.5 measured
SREBench (Vals AI)Not measured3.8%Only GPT-5.5 measured
Finance Agent (Vals AI)44.8%51.8%GPT-5.5
Tax Agent Bench (Vals AI)Not measured21.8%Only GPT-5.5 measured
Legal Research Bench (Vals AI)27.9%40.4%GPT-5.5
Excel Modeling Benchmark (Vals AI)Not measured64.5%Only GPT-5.5 measured
Time Horizon Index (Vals AI)Not measured8.3%Only GPT-5.5 measured
τ²-Bench Telecom97.7%93.9%GLM 5.1
APEX-Agents40.9%55.1%GPT-5.5
Remote Labor IndexNot measured6.3%Only GPT-5.5 measured
OSWorld 2.0Not measured13.0%Only GPT-5.5 measured
DeepResearch BenchNot measured54.0%Only GPT-5.5 measured
PostTrainBenchNot measured27.2%Only GPT-5.5 measured
Vending-Bench 2$5,634$7,524GPT-5.5
Neither model has a result on the other 13 boards here
ReasoningLike-for-likePublic boards, shown as published, kept out of the index09
Reasoning benchmarks for GLM 5.1 and GPT-5.5
BenchmarkGLM 5.1GPT-5.5Leader
GPQA Diamond84.5%93.2%GPT-5.5
LiveBench reasoningNot measured89.7%Only GPT-5.5 measured
MMMU Pro (Vals AI)Not measured88.3%Only GPT-5.5 measured
GPQA Diamond (Artificial Analysis run)86.8%93.5%GPT-5.5
Humanity's Last Exam (Artificial Analysis run)30.1%45.8%GPT-5.5
GPQA Diamond (Epoch AI run)89.9%90.7%GPT-5.5
ARC-AGINot measured95.0%Only GPT-5.5 measured
ARC-AGI-2Not measured85.0%Only GPT-5.5 measured
SimpleBench55.1%69.0%GPT-5.5
Chess puzzles20.0%63.0%GPT-5.5
Mystery game puzzlesNot measured56.0%Only GPT-5.5 measured
EBR-benchNot measured34.3%Only GPT-5.5 measured
LMArena Text: hard prompts14731489GPT-5.5
LMArena Text: expert14781507GPT-5.5
LMArena Text: hard prompts in English14821483GPT-5.5
LMArena Vision: diagramsNot measured1325Only GPT-5.5 measured
LMArena Vision: homeworkNot measured1332Only GPT-5.5 measured
Neither model has a result on the other 4 boards here
MathLike-for-likePublic boards, shown as published, kept out of the index14
Math benchmarks for GLM 5.1 and GPT-5.5
BenchmarkGLM 5.1GPT-5.5Leader
AIME91.9%Not measuredOnly GLM 5.1 measured
OTIS Mock AIME93.3%84.4%GLM 5.1
FrontierMath, tiers 1 to 336.8%85.3%GPT-5.5
FrontierMath, tier 4Not measured72.5%Only GPT-5.5 measured
ProofBench22.2%50.0%GPT-5.5
LMArena Text: math14731487GPT-5.5
LMArena Text: mathematical work14701496GPT-5.5
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 GLM 5.1 and GPT-5.5
BenchmarkGLM 5.1GPT-5.5Leader
MMLU Pro86.9%88.1%GPT-5.5
LegalBench (Vals AI)84.4%86.5%GPT-5.5
CaseLaw (Vals AI)51.5%66.2%GPT-5.5
CorpFin (Vals AI)64.5%68.4%GPT-5.5
TaxEval (Vals AI)71.2%75.0%GPT-5.5
MortgageTax (Vals AI)Not measured68.8%Only GPT-5.5 measured
MedCode (Vals AI)41.6%49.1%GPT-5.5
SimpleQA Verified34.0%63.0%GPT-5.5
LMArena Text: science14781485GPT-5.5
LMArena Text: medicine and healthcare14741465GLM 5.1
LMArena Text: legal and government14651491GPT-5.5
LMArena Text: business and finance14521478GPT-5.5
Neither model has a result on the other 5 boards here
Web designLike-for-likePublic boards, shown as published, kept out of the index53
Web design benchmarks for GLM 5.1 and GPT-5.5
BenchmarkGLM 5.1GPT-5.5Leader
Design Arena: websites12901256GLM 5.1
Design Arena: UI components12921260GLM 5.1
Design Arena: game dev12651294GPT-5.5
Design Arena: data viz13661265GLM 5.1
Design Arena: 3D13361198GLM 5.1
Design Arena: all code categories12681260GLM 5.1
Design Arena: SVG12171234GPT-5.5
Design Arena: ASCII art11421254GPT-5.5
LiveBench designNot measured70.3%Only GPT-5.5 measured
GeneralLike-for-likePublic boards, shown as published, kept out of the index418
General benchmarks for GLM 5.1 and GPT-5.5
BenchmarkGLM 5.1GPT-5.5Leader
LiveBench data analysisNot measured81.6%Only GPT-5.5 measured
Public Benefits Bench (Vals AI)61.8%60.9%GLM 5.1
SAGE (Vals AI)Not measured51.5%Only GPT-5.5 measured
MedScribe (Vals AI)72.3%86.9%GPT-5.5
Vals Multimodal IndexNot measured68.1%Only GPT-5.5 measured
IFBench76.3%75.9%GLM 5.1
Long context reasoning (AA-LCR)73.7%84.3%GPT-5.5
DTBenchNot measured96.0%Only GPT-5.5 measured
LMCANot measured54.3%Only GPT-5.5 measured
Surface Evolver BenchNot measured88.1%Only GPT-5.5 measured
Furniture assemblyNot measured44.2%Only GPT-5.5 measured
ExploitBench18.1%47.4%GPT-5.5
CL-bench LifeNot measured22.2%Only GPT-5.5 measured
LMArena Text14631471GPT-5.5
LMArena Text: instruction following14531478GPT-5.5
LMArena Text: creative writing14531455GPT-5.5
LMArena VisionNot measured1297Only GPT-5.5 measured
LMArena Text: English14761470GLM 5.1
LMArena Text: non-English14481467GPT-5.5
LMArena Text: Chinese15151534GPT-5.5
LMArena Text: German14671480GPT-5.5
LMArena Text: Japanese14351499GPT-5.5
LMArena Text: Korean14241460GPT-5.5
LMArena Text: French14701485GPT-5.5
LMArena Text: Spanish14681468GLM 5.1
LMArena Text: Russian14541473GPT-5.5
LMArena Text: Polish14491465GPT-5.5
LMArena Text: multi-turn14731476GPT-5.5
LMArena Text: longer queries14671484GPT-5.5
LMArena Text: writing and language14541466GPT-5.5
LMArena Text: entertainment and media14421449GPT-5.5
LMArena Vision: EnglishNot measured1292Only GPT-5.5 measured
LMArena Vision: ChineseNot measured1360Only GPT-5.5 measured
LMArena Vision: reading textNot measured1306Only GPT-5.5 measured
LMArena Vision: humorNot measured1293Only GPT-5.5 measured
LMArena Vision: recognizing thingsNot measured1231Only GPT-5.5 measured
LMArena Vision: creative writingNot measured1301Only GPT-5.5 measured
LMArena DocumentNot measured1486Only GPT-5.5 measured
Neither model has a result on the other 8 boards here
Image generationNot comparablePublic boards, shown as published, kept out of the index0 boards, none shared
Image generation benchmarks for GLM 5.1 and GPT-5.5
BenchmarkGLM 5.1GPT-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

GLM 5.1$0.0036Fits in one request
GPT-5.5$0.020Fits in one request

GLM 5.1 costs less

Repository review

50K input + 3K output tokens

GLM 5.1$0.083Fits in one request
GPT-5.5$0.340Fits in one request

GLM 5.1 costs less

Agent loop

200K input + 10K output tokens

GLM 5.1$0.324Exceeds the context window
GPT-5.5$1.30Fits in one request

GLM 5.1 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 GLM 5.1 and GPT-5.5
SpecificationZ.ai GLM 5.1OpenAI GPT-5.5
MakerZ.aiOpenAI
WeightsOpen weightsNo public weights listed
ReleasedApril 7, 2026April 24, 2026
Context window205K1.05M
Input $/Mtok$1.40$5.00
Output $/Mtok$4.40$30.00
Coding index44.067.8
Independent measurements behind it12
Cost per solved task$0.60$1.65
SourceOpenRouter listingOpenRouter listing

Questions

Is GLM 5.1 better than GPT-5.5 for coding?

Pick GPT-5.5 for coding: it scores 67.8 on the Vibe Coding Index against 44.0 for GLM 5.1. Pick GLM 5.1 when output tokens cost 6.8x less, or when a solved task costs $0.60 against $1.65.

Which is cheaper, GLM 5.1 or GPT-5.5?

GLM 5.1 costs $1.40 per million input tokens and $4.40 per million output tokens; GPT-5.5 costs $5.00 and $30.00. Per solved SWE-bench Verified task, GLM 5.1 costs $0.60 and GPT-5.5 $1.65.

Which has the bigger context window, GLM 5.1 or GPT-5.5?

GPT-5.5, with 1.05M tokens against 205K.

How many benchmarks is the GLM 5.1 vs GPT-5.5 comparison based on?

87 benchmarks have a result for both models as of October 21, 2026. GLM 5.1's coding index rests on 1 independent benchmark and GPT-5.5's on 2. Where only one model has a result, the page says so instead of naming a winner.

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