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GLM 5.3 Flash vs GPT-5.1

Updated October 21, 2026. 69 benchmarks have a result for both. Coding is ranked on the Vibe Coding Index; every other board is shown as published.

Replace GLM 5.3 Flash Replace GPT-5.1
GLM 5.3 FlashZ.ai
Coding
71.0
Overall
41.8
Output $/M
$0.50
61
GPT-5.1OpenAI
Coding
53.3
Overall
24.7
Output $/M
$10.00
7
vs boards won of 69 shared, 1 tied

Decision reading

Pick GLM 5.3 Flash for coding: it scores 71.0 on the Vibe Coding Index against 53.3 for GPT-5.1.

Pick GPT-5.1 when what matters is LiveCodeBench (Vals AI) or GPQA Diamond, where it leads.

Model AGLM 5.3 FlashZ.ai71.0/1002 independent benchmarks$0.02 per solved taskModel BGPT-5.1OpenAI53.3/1002 independent benchmarks$1.02 per solved task
Shared results
69
GLM 5.3 Flash only
33
GPT-5.1 only
31
Like-for-like categories
7 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 5.3 Flash 71.0 from 2 benchmarks, GPT-5.1 53.3 from 2 benchmarks.
Widest category
Coding, 20.7 points apart on average over 10 shared benchmarks.
Widest single gap
LMArena WebDev: React: GLM 5.3 Flash 1624 against GPT-5.1 1307, 48.9 points apart on a 0 to 100 scale.
Output price
GLM 5.3 Flash $0.50 against GPT-5.1 $10.00 per million output tokens, 20.0x apart.
Context window
GLM 5.3 Flash takes 1.05M tokens, GPT-5.1 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
CategoryGLM 5.3 FlashBarsGPT-5.1Ties
Coding91
Intelligence20
Reasoning113
Math30
Knowledge52
Web design80
General2311 tie
All shared boards6171 tie
CodingLike-for-likeFour of these boards feed the Vibe Coding Index91
Coding benchmarks for GLM 5.3 Flash and GPT-5.1
BenchmarkGLM 5.3 FlashGPT-5.1Leader
SWE-bench VerifiedNot measured66.0%Only GPT-5.1 measured
LiveBench coding80.6%Not measuredOnly GLM 5.3 Flash measured
LMArena WebDev16071396GLM 5.3 Flash
AA Coding Index71.549.4GLM 5.3 Flash
LiveCodeBench (Vals AI)80.5%86.5%GPT-5.1
SWE-bench Verified (Vals AI)92.0%69.8%GLM 5.3 Flash
Terminal-Bench 4 (Vals AI)37.4%Not measuredOnly GLM 5.3 Flash measured
Vibe Code Bench (Vals AI)30.8%24.6%GLM 5.3 Flash
Code migration (Vals AI)20.5%Not measuredOnly GLM 5.3 Flash measured
ProgramBench (Vals AI)0.0%Not measuredOnly GLM 5.3 Flash measured
IOI (Vals AI)52.5%Not measuredOnly GLM 5.3 Flash measured
Terminal-Bench 2.1 (Vals AI)62.9%Not measuredOnly GLM 5.3 Flash measured
Vibe Code Bench 1-100 (Vals AI)16.0%Not measuredOnly GLM 5.3 Flash measured
SkillsBench (Vals AI)40.2%Not measuredOnly GLM 5.3 Flash measured
CyberBench (Vals AI)67.9%Not measuredOnly GLM 5.3 Flash measured
LiveCodeBench (Artificial Analysis run)Not measured86.8%Only GPT-5.1 measured
SciCode51.6%Not measuredOnly GLM 5.3 Flash measured
Terminal-Bench Hard (Artificial Analysis run)Not measured45.5%Only GPT-5.1 measured
Terminal-BenchNot measured47.6%Only GPT-5.1 measured
FrontierCode31.8%Not measuredOnly GLM 5.3 Flash measured
FrontierSWE18.1%Not measuredOnly GLM 5.3 Flash measured
GSO-BenchNot measured13.7%Only GPT-5.1 measured
WeirdMLNot measured60.8%Only GPT-5.1 measured
ALE-Bench303.6Not measuredOnly GLM 5.3 Flash measured
LMArena Text: coding15071453GLM 5.3 Flash
LMArena Text: software and IT15001454GLM 5.3 Flash
LMArena WebDev: React16241307GLM 5.3 Flash
LMArena WebDev: HTML15771405GLM 5.3 Flash
LMArena WebDev: from an image15781421GLM 5.3 Flash
Neither model has a result on the other 9 boards here
IntelligenceLike-for-likePublic boards, shown as published, kept out of the index20
Intelligence benchmarks for GLM 5.3 Flash and GPT-5.1
BenchmarkGLM 5.3 FlashGPT-5.1Leader
AA Intelligence Index41.824.7GLM 5.3 Flash
Epoch Capabilities Index153.1149.8GLM 5.3 Flash
Agentic workDirectional onlyPublic boards, shown as published, kept out of the index15 boards, none shared
Agentic work benchmarks for GLM 5.3 Flash and GPT-5.1
BenchmarkGLM 5.3 FlashGPT-5.1Leader
AA Agentic Index50.9Not measuredOnly GLM 5.3 Flash measured
LiveBench research70.1%Not measuredOnly GLM 5.3 Flash measured
LiveBench browser84.0%Not measuredOnly GLM 5.3 Flash measured
LiveBench long agentic28.4%Not measuredOnly GLM 5.3 Flash measured
SREBench (Vals AI)0.8%Not measuredOnly GLM 5.3 Flash measured
Finance Agent (Vals AI)57.9%Not measuredOnly GLM 5.3 Flash measured
Tax Agent Bench (Vals AI)31.6%Not measuredOnly GLM 5.3 Flash measured
Legal Research Bench (Vals AI)45.2%Not measuredOnly GLM 5.3 Flash measured
Harvey's Legal Agent Benchmark (Vals AI)10.4%Not measuredOnly GLM 5.3 Flash measured
Excel Modeling Benchmark (Vals AI)55.9%Not measuredOnly GLM 5.3 Flash measured
Terminal-Bench-Science (Vals AI)2.9%Not measuredOnly GLM 5.3 Flash measured
τ²-Bench TelecomNot measured81.9%Only GPT-5.1 measured
APEX-Agents52.8%Not measuredOnly GLM 5.3 Flash measured
DeepResearch BenchNot measured42.8%Only GPT-5.1 measured
Vending-Bench 2Not measured$1,473Only GPT-5.1 measured
Neither model has a result on the other 24 boards here
ReasoningLike-for-likePublic boards, shown as published, kept out of the index113
Reasoning benchmarks for GLM 5.3 Flash and GPT-5.1
BenchmarkGLM 5.3 FlashGPT-5.1Leader
GPQA Diamond86.4%86.6%GPT-5.1
LiveBench reasoning77.6%Not measuredOnly GLM 5.3 Flash measured
MMMU Pro (Vals AI)86.0%83.2%GLM 5.3 Flash
GPQA Diamond (Artificial Analysis run)91.2%87.3%GLM 5.3 Flash
Humanity's Last Exam (Artificial Analysis run)39.9%28.5%GLM 5.3 Flash
GPQA Diamond (Epoch AI run)90.2%87.6%GLM 5.3 Flash
ARC-AGI91.0%72.8%GLM 5.3 Flash
ARC-AGI-265.8%17.6%GLM 5.3 Flash
SimpleBenchNot measured53.2%Only GPT-5.1 measured
Chess puzzles21.0%42.0%GPT-5.1
Mystery game puzzles8.0%19.0%GPT-5.1
VPCTNot measured58.7%Only GPT-5.1 measured
LMArena Text: hard prompts14901457GLM 5.3 Flash
LMArena Text: expert15111470GLM 5.3 Flash
LMArena Text: hard prompts in English14881462GLM 5.3 Flash
LMArena Vision: diagrams13171264GLM 5.3 Flash
LMArena Vision: homework13181272GLM 5.3 Flash
Neither model has a result on the other 4 boards here
MathLike-for-likePublic boards, shown as published, kept out of the index30
Math benchmarks for GLM 5.3 Flash and GPT-5.1
BenchmarkGLM 5.3 FlashGPT-5.1Leader
AIMENot measured93.3%Only GPT-5.1 measured
MGSM (Vals AI)Not measured93.0%Only GPT-5.1 measured
AA Math IndexNot measured94.0Only GPT-5.1 measured
AIME 2025 (Artificial Analysis run)Not measured94.0%Only GPT-5.1 measured
OTIS Mock AIME93.9%88.6%GLM 5.3 Flash
FrontierMath, tiers 1 to 355.8%Not measuredOnly GLM 5.3 Flash measured
FrontierMath, tier 417.1%Not measuredOnly GLM 5.3 Flash measured
ProofBench21.0%Not measuredOnly GLM 5.3 Flash measured
LMArena Text: math15031446GLM 5.3 Flash
LMArena Text: mathematical work14971449GLM 5.3 Flash
Neither model has a result on the other 3 boards here
KnowledgeLike-for-likePublic boards, shown as published, kept out of the index52
Knowledge benchmarks for GLM 5.3 Flash and GPT-5.1
BenchmarkGLM 5.3 FlashGPT-5.1Leader
MMLU Pro86.1%86.4%GPT-5.1
LegalBench (Vals AI)83.9%85.7%GPT-5.1
CaseLaw (Vals AI)Not measured73.4%Only GPT-5.1 measured
CorpFin (Vals AI)Not measured63.8%Only GPT-5.1 measured
TaxEval (Vals AI)75.6%74.9%GLM 5.3 Flash
MortgageTax (Vals AI)Not measured61.4%Only GPT-5.1 measured
MedQA (Vals AI)Not measured96.4%Only GPT-5.1 measured
MedCode (Vals AI)Not measured52.7%Only GPT-5.1 measured
MMLU Pro (Artificial Analysis run)Not measured87.0%Only GPT-5.1 measured
SimpleQA VerifiedNot measured48.0%Only GPT-5.1 measured
LMArena Text: science14841459GLM 5.3 Flash
LMArena Text: medicine and healthcare14751456GLM 5.3 Flash
LMArena Text: legal and government14731459GLM 5.3 Flash
LMArena Text: business and finance14601431GLM 5.3 Flash
Neither model has a result on the other 3 boards here
Web designLike-for-likePublic boards, shown as published, kept out of the index80
Web design benchmarks for GLM 5.3 Flash and GPT-5.1
BenchmarkGLM 5.3 FlashGPT-5.1Leader
Design Arena: websites12721187GLM 5.3 Flash
Design Arena: UI components13161166GLM 5.3 Flash
Design Arena: game dev12791179GLM 5.3 Flash
Design Arena: data viz12621204GLM 5.3 Flash
Design Arena: 3D13161061GLM 5.3 Flash
Design Arena: all code categories12821171GLM 5.3 Flash
Design Arena: SVG12841149GLM 5.3 Flash
Design Arena: ASCII art12691118GLM 5.3 Flash
LiveBench design77.2%Not measuredOnly GLM 5.3 Flash measured
GeneralLike-for-likePublic boards, shown as published, kept out of the index231
General benchmarks for GLM 5.3 Flash and GPT-5.1
BenchmarkGLM 5.3 FlashGPT-5.1Leader
Vals Index50.9%Not measuredOnly GLM 5.3 Flash measured
LiveBench data analysis76.4%Not measuredOnly GLM 5.3 Flash measured
SAGE (Vals AI)Not measured43.2%Only GPT-5.1 measured
MedScribe (Vals AI)88.9%88.1%GLM 5.3 Flash
IFBenchNot measured72.9%Only GPT-5.1 measured
Long context reasoning (AA-LCR)80.0%80.0%Tie
DTBenchNot measured90.1%Only GPT-5.1 measured
LMCANot measured43.9%Only GPT-5.1 measured
CL-benchNot measured23.7%Only GPT-5.1 measured
Surface Evolver Bench52.5%Not measuredOnly GLM 5.3 Flash measured
CL-bench LifeNot measured17.3%Only GPT-5.1 measured
LMArena Text14711443GLM 5.3 Flash
LMArena Text: instruction following14781443GLM 5.3 Flash
LMArena Text: creative writing14411427GLM 5.3 Flash
LMArena Vision12941250GLM 5.3 Flash
LMArena Text: English14741451GLM 5.3 Flash
LMArena Text: non-English14621431GLM 5.3 Flash
LMArena Text: Chinese15311495GLM 5.3 Flash
LMArena Text: German14621438GLM 5.3 Flash
LMArena Text: Japanese14441453GPT-5.1
LMArena Text: Korean14361401GLM 5.3 Flash
LMArena Text: French14911450GLM 5.3 Flash
LMArena Text: Spanish14751433GLM 5.3 Flash
LMArena Text: Russian14651435GLM 5.3 Flash
LMArena Text: Polish14501440GLM 5.3 Flash
LMArena Text: multi-turn14691450GLM 5.3 Flash
LMArena Text: longer queries14811448GLM 5.3 Flash
LMArena Text: writing and language14551428GLM 5.3 Flash
LMArena Text: entertainment and media14401415GLM 5.3 Flash
LMArena Vision: English12951252GLM 5.3 Flash
LMArena Vision: Chinese13631270GLM 5.3 Flash
LMArena Vision: reading text12991255GLM 5.3 Flash
LMArena Vision: humor12791263GLM 5.3 Flash
LMArena Vision: captioningNot measured1252Only GPT-5.1 measured
LMArena Vision: recognizing thingsNot measured1232Only GPT-5.1 measured
LMArena Vision: creative writing12701266GLM 5.3 Flash
LMArena DocumentNot measured1403Only GPT-5.1 measured
Neither model has a result on the other 9 boards here
Image generationNot comparablePublic boards, shown as published, kept out of the index0 boards, none shared
Image generation benchmarks for GLM 5.3 Flash and GPT-5.1
BenchmarkGLM 5.3 FlashGPT-5.1Leader
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 5.3 Flash$0.0004Fits in one request
GPT-5.1$0.0063Fits in one request

GLM 5.3 Flash costs less

Repository review

50K input + 3K output tokens

GLM 5.3 Flash$0.0090Fits in one request
GPT-5.1$0.092Fits in one request

GLM 5.3 Flash costs less

Agent loop

200K input + 10K output tokens

GLM 5.3 Flash$0.035Fits in one request
GPT-5.1$0.350Fits 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 GLM 5.3 Flash and GPT-5.1
SpecificationZ.ai GLM 5.3 FlashOpenAI GPT-5.1
MakerZ.aiOpenAI
WeightsOpen weightsNo public weights listed
ReleasedAugust 26, 2026November 13, 2025
Context window1.05M400K
Input $/Mtok$0.15$1.25
Output $/Mtok$0.50$10.00
Coding index71.053.3
Independent measurements behind it22
Cost per solved task$0.02$1.02
SourceOpenRouter listingOpenRouter listing

Questions

Is GLM 5.3 Flash better than GPT-5.1 for coding?

Pick GLM 5.3 Flash for coding: it scores 71.0 on the Vibe Coding Index against 53.3 for GPT-5.1. Pick GPT-5.1 when what matters is LiveCodeBench (Vals AI) or GPQA Diamond, where it leads.

Which is cheaper, GLM 5.3 Flash or GPT-5.1?

GLM 5.3 Flash costs $0.15 per million input tokens and $0.50 per million output tokens; GPT-5.1 costs $1.25 and $10.00. Per solved SWE-bench Verified task, GLM 5.3 Flash costs $0.02 and GPT-5.1 $1.02.

Which has the bigger context window, GLM 5.3 Flash or GPT-5.1?

GLM 5.3 Flash, with 1.05M tokens against 400K.

How many benchmarks is the GLM 5.3 Flash vs GPT-5.1 comparison based on?

69 benchmarks have a result for both models as of October 21, 2026. GLM 5.3 Flash's coding index rests on 2 independent benchmarks and GPT-5.1's on 2. Where only one model has a result, the page says so instead of naming a winner.

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<iframe src="https://llmbenchmark.ai/embed/compare/glm-5-3-flash-vs-gpt-5-1" title="GLM 5.3 Flash vs GPT-5.1, LLMBenchmark.ai" width="100%" height="360" style="border:0;max-width:100%" loading="lazy"></iframe>
<p style="font:13px/1.4 sans-serif;margin:6px 0 0">Source: <a href="https://llmbenchmark.ai/compare/glm-5-3-flash-vs-gpt-5-1">LLMBenchmark.ai, GLM 5.3 Flash vs GPT-5.1</a></p>