Claude Sonnet 4.5 vs GPT-6 Luna
Updated October 21, 2026. 60 benchmarks have a result for both. Coding is ranked on the Vibe Coding Index; every other board is shown as published.
Decision reading
Pick GPT-6 Luna for coding: it scores 71.4 on the Vibe Coding Index against 59.1 for Claude Sonnet 4.5.
Pick Claude Sonnet 4.5 when what matters is LMArena Text: coding or LMArena Text: software and IT, where it leads.
- Shared results
- 60
- Claude Sonnet 4.5 only
- 32
- GPT-6 Luna only
- 42
- 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.
Coding
Vibe Coding Index, four public coding benchmarks
GPT-6 Luna
GPT-6 Luna scores 71.4 against 59.1.
2 benchmarks behind each score
Intelligence
AA Intelligence Index
GPT-6 Luna
GPT-6 Luna leads, 38.1 against 20.7.
Same board, both measured
Agentic work
AA Agentic Index
No call
Only Claude Sonnet 4.5 has a AA Agentic Index result, 15.8.
Directional only
Reasoning
GPQA Diamond
No call
Only Claude Sonnet 4.5 has a GPQA Diamond result, 81.6%.
Directional only
Math
AIME
No call
Only Claude Sonnet 4.5 has a AIME result, 88.2%.
Directional only
Knowledge
MMLU Pro
No call
Only Claude Sonnet 4.5 has a MMLU Pro result, 87.4%.
Directional only
Web design
Design Arena: websites
GPT-6 Luna
GPT-6 Luna leads, 1272 against 1190.
Same board, both measured
General
Vals Index
No call
Only GPT-6 Luna has a Vals Index result, 52.3%.
Directional only
Long documents
Listed context window
GPT-6 Luna
GPT-6 Luna takes 1.05M tokens against 1M.
Listed by OpenRouter
Everyday cost
1K input + 500 output tokens
GPT-6 Luna
Claude Sonnet 4.5 $0.011, GPT-6 Luna $0.0003 per turn.
List prices
Cost per solved task
One SWE-bench Verified task, solved
No call
Only Claude Sonnet 4.5 has the number, $1.16.
Directional only
At a glance
- Coding index
- Claude Sonnet 4.5 59.1 from 2 benchmarks, GPT-6 Luna 71.4 from 2 benchmarks.
- Widest category
- Math, 31.2 points apart on average over 6 shared benchmarks.
- Widest single gap
- Vibe Code Bench (Vals AI): Claude Sonnet 4.5 22.6% against GPT-6 Luna 81.7%, 59.0 points apart on a 0 to 100 scale.
- Output price
- Claude Sonnet 4.5 $15.00 against GPT-6 Luna $0.50 per million output tokens, 30.0x apart.
- Context window
- Claude Sonnet 4.5 takes 1M tokens, GPT-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.
| Category | Claude Sonnet 4.5 | Bars | GPT-6 Luna | Ties |
|---|---|---|---|---|
| Coding | 2 | 4 | ||
| Intelligence | 0 | 2 | ||
| Agentic work | 1 | 2 | ||
| Reasoning | 4 | 4 | ||
| Math | 2 | 4 | ||
| Knowledge | 4 | 2 | ||
| Web design | 1 | 7 | ||
| General | 18 | 3 | ||
| All shared boards | 32 | 28 |
CodingLike-for-likeFour of these boards feed the Vibe Coding Index24
| Benchmark | Claude Sonnet 4.5 | GPT-6 Luna | Leader |
|---|---|---|---|
| SWE-bench Verified | 74.8% | Not measured | Only Claude Sonnet 4.5 measured |
| SWE-bench Multilingual | 67.0% | Not measured | Only Claude Sonnet 4.5 measured |
| LiveBench coding | Not measured | 84.5% | Only GPT-6 Luna measured |
| LMArena WebDev | 1394 | 1578 | GPT-6 Luna |
| AA Coding Index | 52.1 | Not measured | Only Claude Sonnet 4.5 measured |
| LiveCodeBench (Vals AI) | 73.0% | Not measured | Only Claude Sonnet 4.5 measured |
| SWE-bench Verified (Vals AI) | 70.0% | Not measured | Only Claude Sonnet 4.5 measured |
| Terminal-Bench 4 (Vals AI) | Not measured | 13.6% | Only GPT-6 Luna measured |
| Vibe Code Bench (Vals AI) | 22.6% | 81.7% | GPT-6 Luna |
| Code migration (Vals AI) | Not measured | 42.5% | Only GPT-6 Luna measured |
| ProgramBench (Vals AI) | Not measured | 0.5% | Only GPT-6 Luna measured |
| IOI (Vals AI) | Not measured | 55.6% | Only GPT-6 Luna measured |
| Terminal-Bench 2.1 (Vals AI) | Not measured | 73.0% | Only GPT-6 Luna measured |
| SWE-bench Multimodal (Vals AI) | Not measured | 37.5% | Only GPT-6 Luna measured |
| CyberBench (Vals AI) | Not measured | 76.3% | Only GPT-6 Luna measured |
| SciCode | Not measured | 54.6% | Only GPT-6 Luna measured |
| Terminal-Bench | 46.5% | Not measured | Only Claude Sonnet 4.5 measured |
| FrontierCode | Not measured | 42.4% | Only GPT-6 Luna measured |
| GSO-Bench | 14.7% | Not measured | Only Claude Sonnet 4.5 measured |
| WeirdML | 47.7% | Not measured | Only Claude Sonnet 4.5 measured |
| Cybench | 60.0% | Not measured | Only Claude Sonnet 4.5 measured |
| ALE-Bench | Not measured | 1576.9 | Only GPT-6 Luna measured |
| LMArena Text: coding | 1488 | 1437 | Claude Sonnet 4.5 |
| LMArena Text: software and IT | 1473 | 1423 | Claude Sonnet 4.5 |
| LMArena WebDev: React | 1386 | 1573 | GPT-6 Luna |
| LMArena WebDev: HTML | 1399 | 1595 | GPT-6 Luna |
| LMArena WebDev: from an image | Not measured | 1571 | Only GPT-6 Luna measured |
| Neither model has a result on the other 11 boards here | |||
IntelligenceLike-for-likePublic boards, shown as published, kept out of the index02
| Benchmark | Claude Sonnet 4.5 | GPT-6 Luna | Leader |
|---|---|---|---|
| AA Intelligence Index | 20.7 | 38.1 | GPT-6 Luna |
| Epoch Capabilities Index | 146.7 | 156.8 | GPT-6 Luna |
Agentic workLike-for-likePublic boards, shown as published, kept out of the index12
| Benchmark | Claude Sonnet 4.5 | GPT-6 Luna | Leader |
|---|---|---|---|
| AA Agentic Index | 15.8 | Not measured | Only Claude Sonnet 4.5 measured |
| Design Arena: agents building web apps | 1060 | 1189 | GPT-6 Luna |
| Design Arena: agents building full-stack apps | 1050 | 1158 | GPT-6 Luna |
| Design Arena: agents building mobile apps | 1137 | 1133 | Claude Sonnet 4.5 |
| LiveBench research | Not measured | 43.5% | Only GPT-6 Luna measured |
| LiveBench browser | Not measured | 72.0% | Only GPT-6 Luna measured |
| LiveBench long agentic | Not measured | 48.1% | Only GPT-6 Luna measured |
| SREBench (Vals AI) | Not measured | 2.7% | Only GPT-6 Luna measured |
| Finance Agent (Vals AI) | Not measured | 49.9% | Only GPT-6 Luna measured |
| Tax Agent Bench (Vals AI) | Not measured | 19.9% | Only GPT-6 Luna measured |
| Legal Research Bench (Vals AI) | Not measured | 30.3% | Only GPT-6 Luna measured |
| Harvey's Legal Agent Benchmark (Vals AI) | Not measured | 4.2% | Only GPT-6 Luna measured |
| Excel Modeling Benchmark (Vals AI) | Not measured | 68.5% | Only GPT-6 Luna measured |
| BioMysteryBench (Vals AI) | Not measured | 61.5% | Only GPT-6 Luna measured |
| Terminal-Bench-Science (Vals AI) | Not measured | 4.3% | Only GPT-6 Luna measured |
| Vals Science Index | Not measured | 28.4% | Only GPT-6 Luna measured |
| APEX-Agents | Not measured | 44.3% | Only GPT-6 Luna measured |
| METR time horizons | 67.4% | Not measured | Only Claude Sonnet 4.5 measured |
| Remote Labor Index | 2.1% | Not measured | Only Claude Sonnet 4.5 measured |
| GDPval | 42.5% | Not measured | Only Claude Sonnet 4.5 measured |
| DeepResearch Bench | 52.6% | Not measured | Only Claude Sonnet 4.5 measured |
| OSWorld | 62.9% | Not measured | Only Claude Sonnet 4.5 measured |
| SpireClimb | Not measured | 0.0% | Only GPT-6 Luna measured |
| Vending-Bench 2 | $3,839 | Not measured | Only Claude Sonnet 4.5 measured |
| Neither model has a result on the other 15 boards here | |||
ReasoningLike-for-likePublic boards, shown as published, kept out of the index44
| Benchmark | Claude Sonnet 4.5 | GPT-6 Luna | Leader |
|---|---|---|---|
| GPQA Diamond | 81.6% | Not measured | Only Claude Sonnet 4.5 measured |
| LiveBench reasoning | Not measured | 81.8% | Only GPT-6 Luna measured |
| MysteryMechanism (Vals AI) | Not measured | 19.4% | Only GPT-6 Luna measured |
| MMMU Pro (Vals AI) | 79.3% | Not measured | Only Claude Sonnet 4.5 measured |
| Humanity's Last Exam (Artificial Analysis run) | Not measured | 38.5% | Only GPT-6 Luna measured |
| GPQA Diamond (Epoch AI run) | 82.3% | 90.5% | GPT-6 Luna |
| ARC-AGI | 63.7% | 86.7% | GPT-6 Luna |
| ARC-AGI-2 | 13.6% | 59.3% | GPT-6 Luna |
| SimpleBench | 54.3% | Not measured | Only Claude Sonnet 4.5 measured |
| Chess puzzles | 10.0% | 36.0% | GPT-6 Luna |
| Mystery game puzzles | 17.0% | 7.0% | Claude Sonnet 4.5 |
| EBR-bench | 2.4% | Not measured | Only Claude Sonnet 4.5 measured |
| VPCT | 39.8% | Not measured | Only Claude Sonnet 4.5 measured |
| LMArena Text: hard prompts | 1462 | 1410 | Claude Sonnet 4.5 |
| LMArena Text: expert | 1483 | 1442 | Claude Sonnet 4.5 |
| LMArena Text: hard prompts in English | 1471 | 1410 | Claude Sonnet 4.5 |
| LMArena Vision: diagrams | Not measured | 1245 | Only GPT-6 Luna measured |
| LMArena Vision: homework | Not measured | 1261 | Only GPT-6 Luna measured |
| Neither model has a result on the other 3 boards here | |||
MathLike-for-likePublic boards, shown as published, kept out of the index24
| Benchmark | Claude Sonnet 4.5 | GPT-6 Luna | Leader |
|---|---|---|---|
| AIME | 88.2% | Not measured | Only Claude Sonnet 4.5 measured |
| MGSM (Vals AI) | 94.3% | Not measured | Only Claude Sonnet 4.5 measured |
| OTIS Mock AIME | 77.8% | 98.9% | GPT-6 Luna |
| FrontierMath, tiers 1 to 3 | 23.9% | 78.9% | GPT-6 Luna |
| FrontierMath, tier 4 | 2.4% | 56.1% | GPT-6 Luna |
| ProofBench | 19.0% | 64.0% | GPT-6 Luna |
| MATH level 5 | 97.7% | Not measured | Only Claude Sonnet 4.5 measured |
| LMArena Text: math | 1449 | 1409 | Claude Sonnet 4.5 |
| LMArena Text: mathematical work | 1462 | 1427 | Claude Sonnet 4.5 |
| Neither model has a result on the other 4 boards here | |||
KnowledgeLike-for-likePublic boards, shown as published, kept out of the index42
| Benchmark | Claude Sonnet 4.5 | GPT-6 Luna | Leader |
|---|---|---|---|
| MMLU Pro | 87.4% | Not measured | Only Claude Sonnet 4.5 measured |
| LegalBench (Vals AI) | 84.1% | Not measured | Only Claude Sonnet 4.5 measured |
| CaseLaw (Vals AI) | 62.2% | Not measured | Only Claude Sonnet 4.5 measured |
| CorpFin (Vals AI) | 62.0% | Not measured | Only Claude Sonnet 4.5 measured |
| TaxEval (Vals AI) | 73.3% | Not measured | Only Claude Sonnet 4.5 measured |
| MortgageTax (Vals AI) | 64.0% | Not measured | Only Claude Sonnet 4.5 measured |
| MedQA (Vals AI) | 94.7% | Not measured | Only Claude Sonnet 4.5 measured |
| MedCode (Vals AI) | 44.1% | 44.7% | GPT-6 Luna |
| SimpleQA Verified | 30.7% | 41.4% | GPT-6 Luna |
| LMArena Text: science | 1448 | 1386 | Claude Sonnet 4.5 |
| LMArena Text: medicine and healthcare | 1444 | 1352 | Claude Sonnet 4.5 |
| LMArena Text: legal and government | 1451 | 1400 | Claude Sonnet 4.5 |
| LMArena Text: business and finance | 1440 | 1388 | Claude Sonnet 4.5 |
| Neither model has a result on the other 4 boards here | |||
Web designLike-for-likePublic boards, shown as published, kept out of the index17
| Benchmark | Claude Sonnet 4.5 | GPT-6 Luna | Leader |
|---|---|---|---|
| Design Arena: websites | 1190 | 1272 | GPT-6 Luna |
| Design Arena: UI components | 1173 | 1297 | GPT-6 Luna |
| Design Arena: game dev | 1166 | 1259 | GPT-6 Luna |
| Design Arena: data viz | 1167 | 1215 | GPT-6 Luna |
| Design Arena: 3D | 1158 | 1217 | GPT-6 Luna |
| Design Arena: all code categories | 1183 | 1271 | GPT-6 Luna |
| Design Arena: SVG | 1114 | 1253 | GPT-6 Luna |
| Design Arena: ASCII art | 1204 | 1156 | Claude Sonnet 4.5 |
| LiveBench design | Not measured | 82.5% | Only GPT-6 Luna measured |
GeneralLike-for-likePublic boards, shown as published, kept out of the index183
| Benchmark | Claude Sonnet 4.5 | GPT-6 Luna | Leader |
|---|---|---|---|
| Vals Index | Not measured | 52.3% | Only GPT-6 Luna measured |
| LiveBench data analysis | Not measured | 73.4% | Only GPT-6 Luna measured |
| Public Benefits Bench (Vals AI) | Not measured | 57.6% | Only GPT-6 Luna measured |
| SAGE (Vals AI) | 36.1% | 48.1% | GPT-6 Luna |
| MedScribe (Vals AI) | 84.5% | 83.7% | Claude Sonnet 4.5 |
| Long context reasoning (AA-LCR) | Not measured | 83.3% | Only GPT-6 Luna measured |
| DTBench | 83.2% | 90.1% | GPT-6 Luna |
| LMCA | 38.8% | 44.5% | GPT-6 Luna |
| Furniture assembly | Not measured | 44.2% | Only GPT-6 Luna measured |
| LMArena Text | 1438 | 1389 | Claude Sonnet 4.5 |
| LMArena Text: instruction following | 1459 | 1408 | Claude Sonnet 4.5 |
| LMArena Text: creative writing | 1442 | 1363 | Claude Sonnet 4.5 |
| LMArena Vision | Not measured | 1216 | Only GPT-6 Luna measured |
| LMArena Text: English | 1450 | 1393 | Claude Sonnet 4.5 |
| LMArena Text: non-English | 1425 | 1381 | Claude Sonnet 4.5 |
| LMArena Text: Chinese | 1460 | 1427 | Claude Sonnet 4.5 |
| LMArena Text: German | 1427 | 1376 | Claude Sonnet 4.5 |
| LMArena Text: Japanese | 1390 | 1369 | Claude Sonnet 4.5 |
| LMArena Text: Korean | 1402 | 1359 | Claude Sonnet 4.5 |
| LMArena Text: French | 1459 | 1408 | Claude Sonnet 4.5 |
| LMArena Text: Spanish | 1458 | 1391 | Claude Sonnet 4.5 |
| LMArena Text: Russian | 1437 | 1392 | Claude Sonnet 4.5 |
| LMArena Text: Polish | 1423 | 1383 | Claude Sonnet 4.5 |
| LMArena Text: multi-turn | 1465 | 1392 | Claude Sonnet 4.5 |
| LMArena Text: longer queries | 1475 | 1408 | Claude Sonnet 4.5 |
| LMArena Text: writing and language | 1442 | 1384 | Claude Sonnet 4.5 |
| LMArena Text: entertainment and media | 1428 | 1364 | Claude Sonnet 4.5 |
| LMArena Vision: English | Not measured | 1204 | Only GPT-6 Luna measured |
| LMArena Vision: Chinese | Not measured | 1266 | Only GPT-6 Luna measured |
| LMArena Vision: reading text | Not measured | 1225 | Only GPT-6 Luna measured |
| LMArena Vision: creative writing | Not measured | 1205 | Only GPT-6 Luna measured |
| LMArena Document | 1450 | Not measured | Only Claude Sonnet 4.5 measured |
| Neither model has a result on the other 14 boards here | |||
Image generationNot comparablePublic boards, shown as published, kept out of the index0 boards, none shared
| Benchmark | Claude Sonnet 4.5 | GPT-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
GPT-6 Luna costs less
Repository review
50K input + 3K output tokens
GPT-6 Luna costs less
Agent loop
200K input + 10K output tokens
GPT-6 Luna 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.
| Specification | Anthropic Claude Sonnet 4.5 | OpenAI GPT-6 Luna |
|---|---|---|
| Maker | Anthropic | OpenAI |
| Weights | No public weights listed | No public weights listed |
| Released | September 29, 2025 | September 22, 2026 |
| Context window | 1M | 1.05M |
| Input $/Mtok | $3.00 | $0.10 |
| Output $/Mtok | $15.00 | $0.50 |
| Coding index | 59.1 | 71.4 |
| Independent measurements behind it | 2 | 2 |
| Cost per solved task | $1.16 | Not computable |
| Source | OpenRouter listing | OpenRouter listing |
Questions
Is Claude Sonnet 4.5 better than GPT-6 Luna for coding?
Pick GPT-6 Luna for coding: it scores 71.4 on the Vibe Coding Index against 59.1 for Claude Sonnet 4.5. Pick Claude Sonnet 4.5 when what matters is LMArena Text: coding or LMArena Text: software and IT, where it leads.
Which is cheaper, Claude Sonnet 4.5 or GPT-6 Luna?
Claude Sonnet 4.5 costs $3.00 per million input tokens and $15.00 per million output tokens; GPT-6 Luna costs $0.10 and $0.50. Cost per solved task is known for Claude Sonnet 4.5 only.
Which has the bigger context window, Claude Sonnet 4.5 or GPT-6 Luna?
GPT-6 Luna, with 1.05M tokens against 1M.
How many benchmarks is the Claude Sonnet 4.5 vs GPT-6 Luna comparison based on?
60 benchmarks have a result for both models as of October 21, 2026. Claude Sonnet 4.5's coding index rests on 2 independent benchmarks and GPT-6 Luna's on 2. Where only one model has a result, the page says so instead of naming a winner.