GLM 5.3 Flash vs o3

Updated October 21, 2026. 61 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 o3

GLM 5.3 FlashZ.ai

Coding: 71.0
Overall: 41.8
Output $/M: $0.50

o3OpenAI

Coding: 70.7
Overall: 20.2
Output $/M: $8.00

vs boards won of 61 shared

Decision reading

GLM 5.3 Flash and o3 are level for coding, 71.0 against 70.7 on the Vibe Coding Index, so price and context decide.

Pick o3 when what matters is LiveCodeBench (Vals AI) or ALE-Bench, where it leads. Pick GLM 5.3 Flash when output tokens cost 16.0x less, or when a solved task costs $0.02 against $0.571.

Model AGLM 5.3 FlashZ.ai71.0/1002 independent benchmarks$0.02 per solved task Model Bo3OpenAI70.7/1002 independent benchmarks$0.571 per solved task

614136

Shared results: 61
GLM 5.3 Flash only: 41
o3 only: 36
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.

Coding
Vibe Coding Index, four public coding benchmarks
No call
Level: 71.0 against 70.7, inside 2 points.
2 benchmarks behind each score
Intelligence
AA Intelligence Index
GLM 5.3 Flash
GLM 5.3 Flash leads, 41.8 against 20.2.
Same board, both measured
Agentic work
AA Agentic Index
No call
Only GLM 5.3 Flash has a AA Agentic Index result, 50.9.
Directional only
Reasoning
GPQA Diamond
GLM 5.3 Flash
GLM 5.3 Flash leads, 86.4% against 84.1%.
Same board, both measured
Math
AIME
No call
Only o3 has a AIME result, 85.3%.
Directional only
Knowledge
MMLU Pro
GLM 5.3 Flash
GLM 5.3 Flash leads, 86.1% against 85.6%.
Same board, both measured
Web design
Design Arena: websites
GLM 5.3 Flash
GLM 5.3 Flash leads, 1272 against 1036.
Same board, both measured
General
Vals Index
No call
Only GLM 5.3 Flash has a Vals Index result, 50.9%.
Directional only
Long documents
Listed context window
GLM 5.3 Flash
GLM 5.3 Flash takes 1.05M tokens against 200K.
Listed by OpenRouter
Everyday cost
1K input + 500 output tokens
GLM 5.3 Flash
GLM 5.3 Flash $0.0004, o3 $0.0060 per turn.
List prices
Cost per solved task
One SWE-bench Verified task, solved
GLM 5.3 Flash
GLM 5.3 Flash $0.02, o3 $0.571.
Published attempt cost and pass rate

At a glance

Coding index: GLM 5.3 Flash 71.0 from 2 benchmarks, o3 70.7 from 2 benchmarks.
Widest category: Web design, 27.6 points apart on average over 5 shared benchmarks.
Widest single gap: ARC-AGI-2: GLM 5.3 Flash 65.8% against o3 6.5%, 59.3 points apart on a 0 to 100 scale.
Output price: GLM 5.3 Flash $0.50 against o3 $8.00 per million output tokens, 16.0x apart.
Context window: GLM 5.3 Flash takes 1.05M tokens, o3 200K.

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
Category	GLM 5.3 Flash	o3
Coding	2	2
Intelligence	2	0
Reasoning	12	2
Math	4	0
Knowledge	7	0
Web design	5	0
General	25	0
All shared boards	57	4

CodingLike-for-likeFour of these boards feed the Vibe Coding Index22

Coding benchmarks for GLM 5.3 Flash and o3
Benchmark	GLM 5.3 Flash	o3	Leader
Aider polyglot	Not measured	81.3%	Only o3 measured
SWE-bench Verified	Not measured	58.4%	Only o3 measured
SWE-bench Multimodal	Not measured	36.0%	Only o3 measured
LiveBench coding	80.6%	Not measured	Only GLM 5.3 Flash measured
LMArena WebDev	1607	Not measured	Only GLM 5.3 Flash measured
AA Coding Index	71.5	Not measured	Only GLM 5.3 Flash measured
LiveCodeBench (Vals AI)	80.5%	83.9%	o3
SWE-bench Verified (Vals AI)	92.0%	Not measured	Only GLM 5.3 Flash measured
Terminal-Bench 4 (Vals AI)	37.4%	Not measured	Only GLM 5.3 Flash measured
Vibe Code Bench (Vals AI)	30.8%	Not measured	Only GLM 5.3 Flash measured
Code migration (Vals AI)	20.5%	Not measured	Only GLM 5.3 Flash measured
ProgramBench (Vals AI)	0.0%	Not measured	Only GLM 5.3 Flash measured
IOI (Vals AI)	52.5%	Not measured	Only GLM 5.3 Flash measured
Terminal-Bench 2.1 (Vals AI)	62.9%	Not measured	Only GLM 5.3 Flash measured
Vibe Code Bench 1-100 (Vals AI)	16.0%	Not measured	Only GLM 5.3 Flash measured
SkillsBench (Vals AI)	40.2%	Not measured	Only GLM 5.3 Flash measured
CyberBench (Vals AI)	67.9%	Not measured	Only GLM 5.3 Flash measured
LiveCodeBench (Artificial Analysis run)	Not measured	80.8%	Only o3 measured
SciCode	51.6%	Not measured	Only GLM 5.3 Flash measured
Terminal-Bench Hard (Artificial Analysis run)	Not measured	37.1%	Only o3 measured
FrontierCode	31.8%	Not measured	Only GLM 5.3 Flash measured
FrontierSWE	18.1%	Not measured	Only GLM 5.3 Flash measured
GSO-Bench	Not measured	8.8%	Only o3 measured
WeirdML	Not measured	52.4%	Only o3 measured
ALE-Bench	303.6	933.5	o3
LMArena Text: coding	1507	1407	GLM 5.3 Flash
LMArena Text: software and IT	1500	1415	GLM 5.3 Flash
LMArena WebDev: React	1624	Not measured	Only GLM 5.3 Flash measured
LMArena WebDev: HTML	1577	Not measured	Only GLM 5.3 Flash measured
LMArena WebDev: from an image	1578	Not measured	Only GLM 5.3 Flash measured
Neither model has a result on the other 8 boards here

IntelligenceLike-for-likePublic boards, shown as published, kept out of the index20

Intelligence benchmarks for GLM 5.3 Flash and o3
Benchmark	GLM 5.3 Flash	o3	Leader
AA Intelligence Index	41.8	20.2	GLM 5.3 Flash
Epoch Capabilities Index	153.1	146.7	GLM 5.3 Flash

Agentic workDirectional onlyPublic boards, shown as published, kept out of the index17 boards, none shared

Agentic work benchmarks for GLM 5.3 Flash and o3
Benchmark	GLM 5.3 Flash	o3	Leader
AA Agentic Index	50.9	Not measured	Only GLM 5.3 Flash measured
LiveBench research	70.1%	Not measured	Only GLM 5.3 Flash measured
LiveBench browser	84.0%	Not measured	Only GLM 5.3 Flash measured
LiveBench long agentic	28.4%	Not measured	Only GLM 5.3 Flash measured
SREBench (Vals AI)	0.8%	Not measured	Only GLM 5.3 Flash measured
Finance Agent (Vals AI)	57.9%	Not measured	Only GLM 5.3 Flash measured
Tax Agent Bench (Vals AI)	31.6%	Not measured	Only GLM 5.3 Flash measured
Legal Research Bench (Vals AI)	45.2%	Not measured	Only GLM 5.3 Flash measured
Harvey's Legal Agent Benchmark (Vals AI)	10.4%	Not measured	Only GLM 5.3 Flash measured
Excel Modeling Benchmark (Vals AI)	55.9%	Not measured	Only GLM 5.3 Flash measured
Terminal-Bench-Science (Vals AI)	2.9%	Not measured	Only GLM 5.3 Flash measured
τ²-Bench Telecom	Not measured	80.7%	Only o3 measured
APEX-Agents	52.8%	Not measured	Only GLM 5.3 Flash measured
METR time horizons	Not measured	65.4%	Only o3 measured
GDPval	Not measured	30.8%	Only o3 measured
DeepResearch Bench	Not measured	45.2%	Only o3 measured
OSWorld	Not measured	23.0%	Only o3 measured
Neither model has a result on the other 22 boards here

ReasoningLike-for-likePublic boards, shown as published, kept out of the index122

Reasoning benchmarks for GLM 5.3 Flash and o3
Benchmark	GLM 5.3 Flash	o3	Leader
GPQA Diamond	86.4%	84.1%	GLM 5.3 Flash
LiveBench reasoning	77.6%	Not measured	Only GLM 5.3 Flash measured
MMMU Pro (Vals AI)	86.0%	80.4%	GLM 5.3 Flash
GPQA Diamond (Artificial Analysis run)	91.2%	82.7%	GLM 5.3 Flash
Humanity's Last Exam (Artificial Analysis run)	39.9%	20.1%	GLM 5.3 Flash
GPQA Diamond (Epoch AI run)	90.2%	81.8%	GLM 5.3 Flash
ARC-AGI	91.0%	60.8%	GLM 5.3 Flash
ARC-AGI-2	65.8%	6.5%	GLM 5.3 Flash
SimpleBench	Not measured	53.1%	Only o3 measured
Chess puzzles	21.0%	37.0%	o3
Mystery game puzzles	8.0%	29.0%	o3
VPCT	Not measured	52.0%	Only o3 measured
LMArena Text: hard prompts	1490	1402	GLM 5.3 Flash
LMArena Text: expert	1511	1402	GLM 5.3 Flash
LMArena Text: hard prompts in English	1488	1411	GLM 5.3 Flash
LMArena Vision: diagrams	1317	1220	GLM 5.3 Flash
LMArena Vision: homework	1318	1234	GLM 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 index40

Math benchmarks for GLM 5.3 Flash and o3
Benchmark	GLM 5.3 Flash	o3	Leader
AIME	Not measured	85.3%	Only o3 measured
MATH 500 (Vals AI)	Not measured	94.6%	Only o3 measured
MGSM (Vals AI)	Not measured	91.8%	Only o3 measured
AA Math Index	Not measured	88.3	Only o3 measured
AIME 2025 (Artificial Analysis run)	Not measured	88.3%	Only o3 measured
OTIS Mock AIME	93.9%	84.4%	GLM 5.3 Flash
FrontierMath, tiers 1 to 3	55.8%	33.3%	GLM 5.3 Flash
FrontierMath, tier 4	17.1%	Not measured	Only GLM 5.3 Flash measured
ProofBench	21.0%	Not measured	Only GLM 5.3 Flash measured
MATH level 5	Not measured	97.8%	Only o3 measured
LMArena Text: math	1503	1426	GLM 5.3 Flash
LMArena Text: mathematical work	1497	1423	GLM 5.3 Flash
Neither model has a result on the other 1 board here

KnowledgeLike-for-likePublic boards, shown as published, kept out of the index70

Knowledge benchmarks for GLM 5.3 Flash and o3
Benchmark	GLM 5.3 Flash	o3	Leader
MMLU Pro	86.1%	85.6%	GLM 5.3 Flash
LegalBench (Vals AI)	83.9%	83.8%	GLM 5.3 Flash
CorpFin (Vals AI)	Not measured	59.7%	Only o3 measured
TaxEval (Vals AI)	75.6%	74.6%	GLM 5.3 Flash
MortgageTax (Vals AI)	Not measured	65.7%	Only o3 measured
MedQA (Vals AI)	Not measured	96.1%	Only o3 measured
MedCode (Vals AI)	Not measured	47.3%	Only o3 measured
MMLU Pro (Artificial Analysis run)	Not measured	85.3%	Only o3 measured
SimpleQA Verified	Not measured	49.4%	Only o3 measured
GeoBench	Not measured	74.0%	Only o3 measured
LMArena Text: science	1484	1429	GLM 5.3 Flash
LMArena Text: medicine and healthcare	1475	1448	GLM 5.3 Flash
LMArena Text: legal and government	1473	1428	GLM 5.3 Flash
LMArena Text: business and finance	1460	1393	GLM 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 index50

Web design benchmarks for GLM 5.3 Flash and o3
Benchmark	GLM 5.3 Flash	o3	Leader
Design Arena: websites	1272	1036	GLM 5.3 Flash
Design Arena: UI components	1316	1016	GLM 5.3 Flash
Design Arena: game dev	1279	1034	GLM 5.3 Flash
Design Arena: data viz	1262	1200	GLM 5.3 Flash
Design Arena: 3D	1316	Not measured	Only GLM 5.3 Flash measured
Design Arena: all code categories	1282	1021	GLM 5.3 Flash
Design Arena: SVG	1284	Not measured	Only GLM 5.3 Flash measured
Design Arena: ASCII art	1269	Not measured	Only GLM 5.3 Flash measured
LiveBench design	77.2%	Not measured	Only GLM 5.3 Flash measured

GeneralLike-for-likePublic boards, shown as published, kept out of the index250

General benchmarks for GLM 5.3 Flash and o3
Benchmark	GLM 5.3 Flash	o3	Leader
Vals Index	50.9%	Not measured	Only GLM 5.3 Flash measured
LiveBench data analysis	76.4%	Not measured	Only GLM 5.3 Flash measured
SAGE (Vals AI)	Not measured	41.8%	Only o3 measured
MedScribe (Vals AI)	88.9%	76.7%	GLM 5.3 Flash
IFBench	Not measured	71.4%	Only o3 measured
Long context reasoning (AA-LCR)	80.0%	74.7%	GLM 5.3 Flash
DTBench	Not measured	84.8%	Only o3 measured
LMCA	Not measured	39.7%	Only o3 measured
Fiction.LiveBench	Not measured	88.9%	Only o3 measured
Creative writing (Lech Mazur)	Not measured	83.9%	Only o3 measured
CL-bench	Not measured	17.8%	Only o3 measured
Surface Evolver Bench	52.5%	Not measured	Only GLM 5.3 Flash measured
LMArena Text	1471	1410	GLM 5.3 Flash
LMArena Text: instruction following	1478	1368	GLM 5.3 Flash
LMArena Text: creative writing	1441	1359	GLM 5.3 Flash
LMArena Vision	1294	1214	GLM 5.3 Flash
LMArena Text: English	1474	1417	GLM 5.3 Flash
LMArena Text: non-English	1462	1401	GLM 5.3 Flash
LMArena Text: Chinese	1531	1437	GLM 5.3 Flash
LMArena Text: German	1462	1420	GLM 5.3 Flash
LMArena Text: Japanese	1444	1403	GLM 5.3 Flash
LMArena Text: Korean	1436	1370	GLM 5.3 Flash
LMArena Text: French	1491	1430	GLM 5.3 Flash
LMArena Text: Spanish	1475	1395	GLM 5.3 Flash
LMArena Text: Russian	1465	1406	GLM 5.3 Flash
LMArena Text: Polish	1450	1438	GLM 5.3 Flash
LMArena Text: multi-turn	1469	1405	GLM 5.3 Flash
LMArena Text: longer queries	1481	1372	GLM 5.3 Flash
LMArena Text: writing and language	1455	1372	GLM 5.3 Flash
LMArena Text: entertainment and media	1440	1373	GLM 5.3 Flash
LMArena Vision: English	1295	1221	GLM 5.3 Flash
LMArena Vision: Chinese	1363	1237	GLM 5.3 Flash
LMArena Vision: reading text	1299	1218	GLM 5.3 Flash
LMArena Vision: humor	1279	1222	GLM 5.3 Flash
LMArena Vision: captioning	Not measured	1210	Only o3 measured
LMArena Vision: recognizing things	Not measured	1234	Only o3 measured
LMArena Vision: creative writing	1270	1201	GLM 5.3 Flash
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 o3
Benchmark	GLM 5.3 Flash	o3	Leader
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

o3$0.0060Fits 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

o3$0.124Fits 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

o3$0.480Exceeds the context window

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 o3
Specification	Z.ai GLM 5.3 Flash	OpenAI o3
Maker	Z.ai	OpenAI
Weights	Open weights	No public weights listed
Released	August 26, 2026	April 16, 2025
Context window	1.05M	200K
Input $/Mtok	$0.15	$2.00
Output $/Mtok	$0.50	$8.00
Coding index	71.0	70.7
Independent measurements behind it	2	2
Cost per solved task	$0.02	$0.571
Source	OpenRouter listing	OpenRouter listing

Questions

Is GLM 5.3 Flash better than o3 for coding?

GLM 5.3 Flash and o3 are level for coding, 71.0 against 70.7 on the Vibe Coding Index, so price and context decide. Pick o3 when what matters is LiveCodeBench (Vals AI) or ALE-Bench, where it leads. Pick GLM 5.3 Flash when output tokens cost 16.0x less, or when a solved task costs $0.02 against $0.571.

Which is cheaper, GLM 5.3 Flash or o3?

GLM 5.3 Flash costs $0.15 per million input tokens and $0.50 per million output tokens; o3 costs $2.00 and $8.00. Per solved SWE-bench Verified task, GLM 5.3 Flash costs $0.02 and o3 $0.571.

Which has the bigger context window, GLM 5.3 Flash or o3?

GLM 5.3 Flash, with 1.05M tokens against 200K.

How many benchmarks is the GLM 5.3 Flash vs o3 comparison based on?

61 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 o3'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-o3" title="GLM 5.3 Flash vs o3, LLMBenchmark.ai" width="100%" height="360" style="border:0;max-width:100%" loading="lazy"></iframe>
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Decision reading

Which one for your work

Coding

Intelligence

Agentic work

Reasoning

Math

Knowledge

Web design

General

Long documents

Everyday cost

Cost per solved task

At a glance

Benchmark by benchmark

What each workload costs

Chat turn

Repository review

Agent loop

Specification differences

Questions

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