GLM 5.3 Flash vs GPT-5.6 Luna

GPT-5.6 Luna leads GLM 5.3 Flash on coding, 58.0 to 57.7 on the Vibe Coding Index, and GLM 5.3 Flash costs 2.4x less per output token ($0.50 vs $1.20 per million). Updated October 22, 2026; 98 benchmarks have a result for both.

Replace GLM 5.3 Flash Replace GPT-5.6 Luna

GLM 5.3 FlashZ.ai

Coding: 57.7
Overall: 66.0
Output $/M: $0.50

GPT-5.6 LunaOpenAI

Coding: 58.0
Overall: 61.6
Output $/M: $1.20

vs boards won of 98 shared, 1 tied

GLM 5.3 Flash or GPT-5.6 Luna: which to pick

GLM 5.3 Flash and GPT-5.6 Luna are level for coding, 57.7 against 58.0 on the Vibe Coding Index, so price and context decide.

Pick GLM 5.3 Flash for output tokens 2.4x cheaper ($0.50 vs $1.20 per million) and a lower cost per solved task ($0.02 against $0.04). Pick GPT-5.6 Luna for a larger context window (1.05M against 1.05M tokens) and work measured by SWE-bench Verified (Vals AI) or Vibe Code Bench (Vals AI), where it leads.

Model AGLM 5.3 FlashZ.ai57.7/1006 independent benchmarks$0.02 per solved task Model BGPT-5.6 LunaOpenAI58.0/1006 independent benchmarks$0.04 per solved task

98421

Shared results: 98
GLM 5.3 Flash only: 4
GPT-5.6 Luna only: 21
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.

Coding
Vibe Coding Index, six public coding benchmarks
No call
Level: 57.7 against 58.0, inside 2 points.
6 benchmarks behind each score
Intelligence
AA Intelligence Index
GLM 5.3 Flash
GLM 5.3 Flash leads, 41.8 against 37.3.
Same board, both measured
Agentic work
AA Agentic Index
GLM 5.3 Flash
GLM 5.3 Flash leads, 50.9 against 42.1.
Same board, both measured
Reasoning
GPQA Diamond
GPT-5.6 Luna
GPT-5.6 Luna leads, 91.7% against 86.4%.
Same board, both measured
Knowledge
MMLU Pro
GLM 5.3 Flash
GLM 5.3 Flash leads, 86.1% against 86.0%.
Same board, both measured
Web design
Design Arena: websites
GLM 5.3 Flash
GLM 5.3 Flash leads, 1272 against 1255.
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
GPT-5.6 Luna
GPT-5.6 Luna takes 1.05M tokens against 1.05M.
Listed by OpenRouter
Everyday cost
1K input + 500 output tokens
GLM 5.3 Flash
GLM 5.3 Flash $0.0004, GPT-5.6 Luna $0.0008 per turn.
List prices
Cost per solved task
One SWE-bench Verified task, solved
GLM 5.3 Flash
GLM 5.3 Flash $0.02, GPT-5.6 Luna $0.04.
Published attempt cost and pass rate

At a glance

Coding index: GLM 5.3 Flash 57.7 from 6 benchmarks, GPT-5.6 Luna 58.0 from 6 benchmarks.
Widest category: Math, 20.9 points apart on average over 6 shared benchmarks.
Widest single gap: Vibe Code Bench (Vals AI): GLM 5.3 Flash 30.8% against GPT-5.6 Luna 77.1%, 46.3 points apart on a 0 to 100 scale.
Output price: GLM 5.3 Flash $0.50 against GPT-5.6 Luna $1.20 per million output tokens, 2.4x apart.
Context window: GLM 5.3 Flash takes 1.05M tokens, GPT-5.6 Luna 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
Category	GLM 5.3 Flash	GPT-5.6 Luna	Ties
Coding	9	11	1 tie
Intelligence	1	1
Agentic work	8	3
Reasoning	10	5
Math	2	4
Knowledge	5	2
Web design	9	0
General	24	3
All shared boards	68	29	1 tie

CodingLike-for-likeSix of these boards feed the Vibe Coding Index911

Coding benchmarks for GLM 5.3 Flash and GPT-5.6 Luna
Benchmark	GLM 5.3 Flash	GPT-5.6 Luna	Leader
LiveBench coding	80.6%	73.6%	GLM 5.3 Flash
LMArena WebDev	1607	1518	GLM 5.3 Flash
AA Coding Index	71.5	71.4	GLM 5.3 Flash
LiveCodeBench (Vals AI)	80.5%	Not measured	Only GLM 5.3 Flash measured
SWE-bench Verified (Vals AI)	92.0%	93.0%	GPT-5.6 Luna
Terminal-Bench 4 (Vals AI)	37.4%	11.6%	GLM 5.3 Flash
Vibe Code Bench (Vals AI)	30.8%	77.1%	GPT-5.6 Luna
Code migration (Vals AI)	20.5%	44.5%	GPT-5.6 Luna
ProgramBench (Vals AI)	0.0%	0.0%	Tie
IOI (Vals AI)	52.5%	61.8%	GPT-5.6 Luna
Terminal-Bench 2.1 (Vals AI)	62.9%	79.0%	GPT-5.6 Luna
Vibe Code Bench 1-100 (Vals AI)	16.0%	22.6%	GPT-5.6 Luna
SkillsBench (Vals AI)	40.2%	60.5%	GPT-5.6 Luna
CyberBench (Vals AI)	67.9%	73.6%	GPT-5.6 Luna
SciCode	51.6%	53.6%	GPT-5.6 Luna
FrontierCode	31.8%	39.8%	GPT-5.6 Luna
FrontierSWE	18.1%	Not measured	Only GLM 5.3 Flash measured
WeirdML	Not measured	60.9%	Only GPT-5.6 Luna measured
ALE-Bench	303.6	1667.4	GPT-5.6 Luna
LMArena Text: coding	1507	1466	GLM 5.3 Flash
LMArena Text: software and IT	1500	1463	GLM 5.3 Flash
LMArena WebDev: React	1624	1508	GLM 5.3 Flash
LMArena WebDev: HTML	1577	1520	GLM 5.3 Flash
LMArena WebDev: from an image	1578	1517	GLM 5.3 Flash
SciCode	Not measured	6.2%	Only GPT-5.6 Luna measured
Neither model has a result on the other 14 boards here

IntelligenceLike-for-likePublic boards, shown as published, kept out of the index11

Intelligence benchmarks for GLM 5.3 Flash and GPT-5.6 Luna
Benchmark	GLM 5.3 Flash	GPT-5.6 Luna	Leader
AA Intelligence Index	41.8	37.3	GLM 5.3 Flash
Epoch Capabilities Index	153.1	156.5	GPT-5.6 Luna

Agentic workLike-for-likePublic boards, shown as published, kept out of the index83

Agentic work benchmarks for GLM 5.3 Flash and GPT-5.6 Luna
Benchmark	GLM 5.3 Flash	GPT-5.6 Luna	Leader
AA Agentic Index	50.9	42.1	GLM 5.3 Flash
LiveBench research	70.1%	51.0%	GLM 5.3 Flash
LiveBench browser	84.0%	68.0%	GLM 5.3 Flash
LiveBench long agentic	28.4%	30.4%	GPT-5.6 Luna
SREBench (Vals AI)	0.8%	1.5%	GPT-5.6 Luna
Finance Agent (Vals AI)	57.9%	55.0%	GLM 5.3 Flash
Tax Agent Bench (Vals AI)	31.6%	24.8%	GLM 5.3 Flash
Legal Research Bench (Vals AI)	45.2%	36.5%	GLM 5.3 Flash
Harvey's Legal Agent Benchmark (Vals AI)	10.4%	Not measured	Only GLM 5.3 Flash measured
Excel Modeling Benchmark (Vals AI)	55.9%	67.1%	GPT-5.6 Luna
BioMysteryBench (Vals AI)	Not measured	61.5%	Only GPT-5.6 Luna measured
Terminal-Bench-Science (Vals AI)	2.9%	0.0%	GLM 5.3 Flash
Vals Science Index	Not measured	25.3%	Only GPT-5.6 Luna measured
APEX-Agents	52.8%	43.0%	GLM 5.3 Flash
BALROG	Not measured	45.6%	Only GPT-5.6 Luna measured
Vending-Bench 2	Not measured	$4,095	Only GPT-5.6 Luna measured
Neither model has a result on the other 25 boards here

ReasoningLike-for-likePublic boards, shown as published, kept out of the index105

Reasoning benchmarks for GLM 5.3 Flash and GPT-5.6 Luna
Benchmark	GLM 5.3 Flash	GPT-5.6 Luna	Leader
GPQA Diamond	86.4%	91.7%	GPT-5.6 Luna
LiveBench reasoning	77.6%	85.6%	GPT-5.6 Luna
MysteryMechanism (Vals AI)	Not measured	14.4%	Only GPT-5.6 Luna measured
MMMU Pro (Vals AI)	86.0%	85.0%	GLM 5.3 Flash
GPQA Diamond (Artificial Analysis run)	91.2%	91.1%	GLM 5.3 Flash
Humanity's Last Exam (Artificial Analysis run)	39.9%	39.5%	GLM 5.3 Flash
GPQA Diamond (Epoch AI run)	90.2%	91.6%	GPT-5.6 Luna
ARC-AGI	91.0%	88.0%	GLM 5.3 Flash
ARC-AGI-2	65.8%	59.5%	GLM 5.3 Flash
SimpleBench	Not measured	46.8%	Only GPT-5.6 Luna measured
Chess puzzles	21.0%	43.0%	GPT-5.6 Luna
Mystery game puzzles	8.0%	21.0%	GPT-5.6 Luna
LMArena Text: hard prompts	1490	1451	GLM 5.3 Flash
LMArena Text: expert	1511	1478	GLM 5.3 Flash
LMArena Text: hard prompts in English	1488	1460	GLM 5.3 Flash
LMArena Vision: diagrams	1317	1273	GLM 5.3 Flash
LMArena Vision: homework	1318	1282	GLM 5.3 Flash
Kagi LLM Benchmark	Not measured	49.1%	Only GPT-5.6 Luna measured
Neither model has a result on the other 4 boards here

MathLike-for-likePublic boards, shown as published, kept out of the index24

Math benchmarks for GLM 5.3 Flash and GPT-5.6 Luna
Benchmark	GLM 5.3 Flash	GPT-5.6 Luna	Leader
OTIS Mock AIME	93.9%	98.3%	GPT-5.6 Luna
FrontierMath, tiers 1 to 3	55.8%	82.1%	GPT-5.6 Luna
FrontierMath, tier 4	17.1%	61.0%	GPT-5.6 Luna
ProofBench	21.0%	60.0%	GPT-5.6 Luna
LMArena Text: math	1503	1459	GLM 5.3 Flash
LMArena Text: mathematical work	1497	1470	GLM 5.3 Flash
Neither model has a result on the other 7 boards here

KnowledgeLike-for-likePublic boards, shown as published, kept out of the index52

Knowledge benchmarks for GLM 5.3 Flash and GPT-5.6 Luna
Benchmark	GLM 5.3 Flash	GPT-5.6 Luna	Leader
MMLU Pro	86.1%	86.0%	GLM 5.3 Flash
LegalBench (Vals AI)	83.9%	84.0%	GPT-5.6 Luna
CorpFin (Vals AI)	Not measured	64.2%	Only GPT-5.6 Luna measured
TaxEval (Vals AI)	75.6%	76.2%	GPT-5.6 Luna
MortgageTax (Vals AI)	Not measured	67.3%	Only GPT-5.6 Luna measured
MedCode (Vals AI)	Not measured	42.4%	Only GPT-5.6 Luna measured
SimpleQA Verified	Not measured	41.0%	Only GPT-5.6 Luna measured
LMArena Text: science	1484	1433	GLM 5.3 Flash
LMArena Text: medicine and healthcare	1475	1399	GLM 5.3 Flash
LMArena Text: legal and government	1473	1446	GLM 5.3 Flash
LMArena Text: business and finance	1460	1439	GLM 5.3 Flash
FACTS Benchmark Suite	Not measured	35.0%	Only GPT-5.6 Luna measured
Neither model has a result on the other 6 boards here

Web designLike-for-likePublic boards, shown as published, kept out of the index90

Web design benchmarks for GLM 5.3 Flash and GPT-5.6 Luna
Benchmark	GLM 5.3 Flash	GPT-5.6 Luna	Leader
Design Arena: websites	1272	1255	GLM 5.3 Flash
Design Arena: UI components	1316	1248	GLM 5.3 Flash
Design Arena: game dev	1278	1194	GLM 5.3 Flash
Design Arena: data viz	1262	1211	GLM 5.3 Flash
Design Arena: 3D	1316	1121	GLM 5.3 Flash
Design Arena: all code categories	1282	1231	GLM 5.3 Flash
Design Arena: SVG	1285	1194	GLM 5.3 Flash
Design Arena: ASCII art	1267	1142	GLM 5.3 Flash
LiveBench design	77.2%	76.0%	GLM 5.3 Flash

GeneralLike-for-likePublic boards, shown as published, kept out of the index243

General benchmarks for GLM 5.3 Flash and GPT-5.6 Luna
Benchmark	GLM 5.3 Flash	GPT-5.6 Luna	Leader
Vals Index	50.9%	Not measured	Only GLM 5.3 Flash measured
LiveBench data analysis	76.4%	78.0%	GPT-5.6 Luna
Public Benefits Bench (Vals AI)	Not measured	61.2%	Only GPT-5.6 Luna measured
SAGE (Vals AI)	Not measured	44.2%	Only GPT-5.6 Luna measured
MedScribe (Vals AI)	88.9%	84.4%	GLM 5.3 Flash
Vals Multimodal Index	Not measured	69.1%	Only GPT-5.6 Luna measured
Long context reasoning (AA-LCR)	80.0%	83.7%	GPT-5.6 Luna
DTBench	Not measured	89.1%	Only GPT-5.6 Luna measured
LMCA	Not measured	48.5%	Only GPT-5.6 Luna measured
Surface Evolver Bench	52.5%	61.9%	GPT-5.6 Luna
Furniture assembly	Not measured	42.5%	Only GPT-5.6 Luna measured
LMArena Text	1471	1431	GLM 5.3 Flash
LMArena Text: instruction following	1478	1437	GLM 5.3 Flash
LMArena Text: creative writing	1441	1396	GLM 5.3 Flash
LMArena Vision	1294	1257	GLM 5.3 Flash
LMArena Text: English	1474	1441	GLM 5.3 Flash
LMArena Text: non-English	1462	1417	GLM 5.3 Flash
LMArena Text: Chinese	1531	1470	GLM 5.3 Flash
LMArena Text: German	1462	1455	GLM 5.3 Flash
LMArena Text: Japanese	1444	1415	GLM 5.3 Flash
LMArena Text: Korean	1436	1415	GLM 5.3 Flash
LMArena Text: French	1491	1458	GLM 5.3 Flash
LMArena Text: Spanish	1475	1446	GLM 5.3 Flash
LMArena Text: Russian	1465	1427	GLM 5.3 Flash
LMArena Text: Polish	1450	1405	GLM 5.3 Flash
LMArena Text: multi-turn	1469	1434	GLM 5.3 Flash
LMArena Text: longer queries	1481	1436	GLM 5.3 Flash
LMArena Text: writing and language	1455	1419	GLM 5.3 Flash
LMArena Text: entertainment and media	1440	1402	GLM 5.3 Flash
LMArena Vision: English	1295	1263	GLM 5.3 Flash
LMArena Vision: Chinese	1363	1294	GLM 5.3 Flash
LMArena Vision: reading text	1299	1264	GLM 5.3 Flash
LMArena Vision: humor	1279	1190	GLM 5.3 Flash
LMArena Vision: creative writing	1270	1257	GLM 5.3 Flash
LMArena Document	Not measured	1457	Only GPT-5.6 Luna measured
Neither model has a result on the other 11 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-5.6 Luna
Benchmark	GLM 5.3 Flash	GPT-5.6 Luna	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

GPT-5.6 Luna$0.0008Fits 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-5.6 Luna$0.014Fits 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-5.6 Luna$0.052Fits 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-5.6 Luna
Specification	Z.ai GLM 5.3 Flash	OpenAI GPT-5.6 Luna
Maker	Z.ai	OpenAI
Weights	Open weights	No public weights listed
Released	August 26, 2026	July 9, 2026
Context window	1.05M	1.05M
Input $/Mtok	$0.15	$0.20
Output $/Mtok	$0.50	$1.20
Coding index	57.7	58.0
Independent measurements behind it	6	6
Cost per solved task	$0.02	$0.04
Source	OpenRouter listing	OpenRouter listing

Questions

Is GLM 5.3 Flash better than GPT-5.6 Luna for coding?

GLM 5.3 Flash and GPT-5.6 Luna are level for coding, 57.7 against 58.0 on the Vibe Coding Index, so price and context decide. Pick GLM 5.3 Flash for output tokens 2.4x cheaper ($0.50 vs $1.20 per million) and a lower cost per solved task ($0.02 against $0.04). Pick GPT-5.6 Luna for a larger context window (1.05M against 1.05M tokens) and work measured by SWE-bench Verified (Vals AI) or Vibe Code Bench (Vals AI), where it leads.

Which is cheaper, GLM 5.3 Flash or GPT-5.6 Luna?

GLM 5.3 Flash costs $0.15 per million input tokens and $0.50 per million output tokens; GPT-5.6 Luna costs $0.20 and $1.20. Per solved SWE-bench Verified task, GLM 5.3 Flash costs $0.02 and GPT-5.6 Luna $0.04.

Which has the bigger context window, GLM 5.3 Flash or GPT-5.6 Luna?

GPT-5.6 Luna, with 1.05M tokens against 1.05M.

How many benchmarks is the GLM 5.3 Flash vs GPT-5.6 Luna comparison based on?

98 benchmarks have a result for both models as of October 22, 2026. GLM 5.3 Flash's coding index rests on 6 independent benchmarks and GPT-5.6 Luna's on 6. Where only one model has a result, the page says so instead of naming a winner.

Compare next

Embed this comparison on your site

Free under CC BY 4.0, while the source link stays visible. Preview the frame · Terms and other embeds

<iframe src="https://llmbenchmark.ai/embed/compare/glm-5-3-flash-vs-gpt-5-6-luna" title="GLM 5.3 Flash vs GPT-5.6 Luna, 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-5-6-luna">LLMBenchmark.ai, GLM 5.3 Flash vs GPT-5.6 Luna</a></p>

GLM 5.3 Flash or GPT-5.6 Luna: which to pick

Which one for your work

Coding

Intelligence

Agentic work

Reasoning

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

Compare next