GPT-6 Luna vs gpt-oss-120b
Updated October 21, 2026. 46 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 34.5 for gpt-oss-120b.
Pick gpt-oss-120b when the benchmark that matters is LMArena Text: medicine and healthcare, where it leads.
- Shared results
- 46
- GPT-6 Luna only
- 56
- gpt-oss-120b only
- 32
- 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 34.5.
2 benchmarks behind each score
Intelligence
AA Intelligence Index
GPT-6 Luna
GPT-6 Luna leads, 38.1 against 11.6.
Same board, both measured
Agentic work
AA Agentic Index
No call
Only gpt-oss-120b has a AA Agentic Index result, 3.7.
Directional only
Reasoning
GPQA Diamond
No call
Only gpt-oss-120b has a GPQA Diamond result, 78.5%.
Directional only
Math
AIME
No call
Only gpt-oss-120b has a AIME result, 92.6%.
Directional only
Knowledge
MMLU Pro
No call
Only gpt-oss-120b has a MMLU Pro result, 79.2%.
Directional only
Web design
Design Arena: websites
GPT-6 Luna
GPT-6 Luna leads, 1272 against 968.
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 131K.
Listed by OpenRouter
Everyday cost
1K input + 500 output tokens
GPT-6 Luna
GPT-6 Luna $0.0003, gpt-oss-120b $0.0004 per turn.
List prices
Cost per solved task
One SWE-bench Verified task, solved
No call
Only gpt-oss-120b has the number, $0.51.
Directional only
At a glance
- Coding index
- GPT-6 Luna 71.4 from 2 benchmarks, gpt-oss-120b 34.5 from 2 benchmarks.
- Widest category
- Agentic work, 39.9 points apart on average over 1 shared benchmark.
- Widest single gap
- Design Arena: UI components: GPT-6 Luna 1297 against gpt-oss-120b 927, 46.3 points apart on a 0 to 100 scale.
- Output price
- GPT-6 Luna $0.50 against gpt-oss-120b $0.60 per million output tokens, 1.2x apart.
- Context window
- GPT-6 Luna takes 1.05M tokens, gpt-oss-120b 131K.
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 | GPT-6 Luna | Bars | gpt-oss-120b | Ties |
|---|---|---|---|---|
| Coding | 4 | 0 | ||
| Intelligence | 2 | 0 | ||
| Agentic work | 1 | 0 | ||
| Reasoning | 6 | 0 | ||
| Math | 3 | 0 | ||
| Knowledge | 3 | 1 | ||
| Web design | 6 | 0 | ||
| General | 20 | 0 | ||
| All shared boards | 45 | 1 |
CodingLike-for-likeFour of these boards feed the Vibe Coding Index40
| Benchmark | GPT-6 Luna | gpt-oss-120b | Leader |
|---|---|---|---|
| Aider polyglot | Not measured | 41.8% | Only gpt-oss-120b measured |
| SWE-bench Verified | Not measured | 26.0% | Only gpt-oss-120b measured |
| LiveBench coding | 84.5% | Not measured | Only GPT-6 Luna measured |
| LMArena WebDev | 1578 | Not measured | Only GPT-6 Luna measured |
| AA Coding Index | Not measured | 30.4 | Only gpt-oss-120b measured |
| LiveCodeBench (Vals AI) | Not measured | 83.2% | Only gpt-oss-120b measured |
| SWE-bench Verified (Vals AI) | Not measured | 33.6% | Only gpt-oss-120b measured |
| Terminal-Bench 4 (Vals AI) | 13.6% | Not measured | Only GPT-6 Luna measured |
| Vibe Code Bench (Vals AI) | 81.7% | Not measured | Only GPT-6 Luna measured |
| Code migration (Vals AI) | 42.5% | Not measured | Only GPT-6 Luna measured |
| ProgramBench (Vals AI) | 0.5% | Not measured | Only GPT-6 Luna measured |
| IOI (Vals AI) | 55.6% | Not measured | Only GPT-6 Luna measured |
| Terminal-Bench 2.1 (Vals AI) | 73.0% | Not measured | Only GPT-6 Luna measured |
| SWE-bench Multimodal (Vals AI) | 37.5% | Not measured | Only GPT-6 Luna measured |
| CyberBench (Vals AI) | 76.3% | Not measured | Only GPT-6 Luna measured |
| LiveCodeBench (Artificial Analysis run) | Not measured | 87.8% | Only gpt-oss-120b measured |
| SciCode | 54.6% | 34.0% | GPT-6 Luna |
| Terminal-Bench Hard (Artificial Analysis run) | Not measured | 23.5% | Only gpt-oss-120b measured |
| Terminal-Bench | Not measured | 18.7% | Only gpt-oss-120b measured |
| FrontierCode | 42.4% | Not measured | Only GPT-6 Luna measured |
| WeirdML | Not measured | 48.2% | Only gpt-oss-120b measured |
| ALE-Bench | 1576.9 | 575.6 | GPT-6 Luna |
| LMArena Text: coding | 1437 | 1379 | GPT-6 Luna |
| LMArena Text: software and IT | 1423 | 1387 | GPT-6 Luna |
| LMArena WebDev: React | 1573 | Not measured | Only GPT-6 Luna measured |
| LMArena WebDev: HTML | 1595 | Not measured | Only GPT-6 Luna measured |
| LMArena WebDev: from an image | 1571 | Not measured | 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 index20
| Benchmark | GPT-6 Luna | gpt-oss-120b | Leader |
|---|---|---|---|
| AA Intelligence Index | 38.1 | 11.6 | GPT-6 Luna |
| Epoch Capabilities Index | 156.8 | 139.8 | GPT-6 Luna |
Agentic workLike-for-likePublic boards, shown as published, kept out of the index10
| Benchmark | GPT-6 Luna | gpt-oss-120b | Leader |
|---|---|---|---|
| AA Agentic Index | Not measured | 3.7 | Only gpt-oss-120b measured |
| Design Arena: agents building web apps | 1189 | Not measured | Only GPT-6 Luna measured |
| Design Arena: agents building full-stack apps | 1158 | Not measured | Only GPT-6 Luna measured |
| Design Arena: agents building mobile apps | 1133 | Not measured | Only GPT-6 Luna measured |
| LiveBench research | 43.5% | Not measured | Only GPT-6 Luna measured |
| LiveBench browser | 72.0% | Not measured | Only GPT-6 Luna measured |
| LiveBench long agentic | 48.1% | Not measured | Only GPT-6 Luna measured |
| SREBench (Vals AI) | 2.7% | Not measured | Only GPT-6 Luna measured |
| Finance Agent (Vals AI) | 49.9% | Not measured | Only GPT-6 Luna measured |
| Tax Agent Bench (Vals AI) | 19.9% | Not measured | Only GPT-6 Luna measured |
| Legal Research Bench (Vals AI) | 30.3% | Not measured | Only GPT-6 Luna measured |
| Harvey's Legal Agent Benchmark (Vals AI) | 4.2% | Not measured | Only GPT-6 Luna measured |
| Excel Modeling Benchmark (Vals AI) | 68.5% | Not measured | Only GPT-6 Luna measured |
| BioMysteryBench (Vals AI) | 61.5% | Not measured | Only GPT-6 Luna measured |
| Terminal-Bench-Science (Vals AI) | 4.3% | Not measured | Only GPT-6 Luna measured |
| Vals Science Index | 28.4% | Not measured | Only GPT-6 Luna measured |
| τ²-Bench Telecom | Not measured | 65.8% | Only gpt-oss-120b measured |
| APEX-Agents | 44.3% | 4.4% | GPT-6 Luna |
| METR time horizons | Not measured | 56.6% | Only gpt-oss-120b measured |
| SpireClimb | 0.0% | Not measured | Only GPT-6 Luna measured |
| Vending-Bench 2 | Not measured | -$22 | Only gpt-oss-120b measured |
| Neither model has a result on the other 18 boards here | |||
ReasoningLike-for-likePublic boards, shown as published, kept out of the index60
| Benchmark | GPT-6 Luna | gpt-oss-120b | Leader |
|---|---|---|---|
| GPQA Diamond | Not measured | 78.5% | Only gpt-oss-120b measured |
| LiveBench reasoning | 81.8% | Not measured | Only GPT-6 Luna measured |
| MysteryMechanism (Vals AI) | 19.4% | Not measured | Only GPT-6 Luna measured |
| GPQA Diamond (Artificial Analysis run) | Not measured | 78.2% | Only gpt-oss-120b measured |
| Humanity's Last Exam (Artificial Analysis run) | 38.5% | 19.6% | GPT-6 Luna |
| GPQA Diamond (Epoch AI run) | 90.5% | 75.8% | GPT-6 Luna |
| ARC-AGI | 86.7% | Not measured | Only GPT-6 Luna measured |
| ARC-AGI-2 | 59.3% | Not measured | Only GPT-6 Luna measured |
| SimpleBench | Not measured | 22.1% | Only gpt-oss-120b measured |
| Chess puzzles | 36.0% | Not measured | Only GPT-6 Luna measured |
| Mystery game puzzles | 7.0% | 2.0% | GPT-6 Luna |
| LMArena Text: hard prompts | 1410 | 1364 | GPT-6 Luna |
| LMArena Text: expert | 1442 | 1356 | GPT-6 Luna |
| LMArena Text: hard prompts in English | 1410 | 1368 | GPT-6 Luna |
| LMArena Vision: diagrams | 1245 | Not measured | Only GPT-6 Luna measured |
| LMArena Vision: homework | 1261 | Not measured | Only GPT-6 Luna measured |
| Neither model has a result on the other 5 boards here | |||
MathLike-for-likePublic boards, shown as published, kept out of the index30
| Benchmark | GPT-6 Luna | gpt-oss-120b | Leader |
|---|---|---|---|
| AIME | Not measured | 92.6% | Only gpt-oss-120b measured |
| MATH 500 (Vals AI) | Not measured | 94.8% | Only gpt-oss-120b measured |
| MGSM (Vals AI) | Not measured | 92.0% | Only gpt-oss-120b measured |
| AA Math Index | Not measured | 93.4 | Only gpt-oss-120b measured |
| AIME 2025 (Artificial Analysis run) | Not measured | 93.4% | Only gpt-oss-120b measured |
| OTIS Mock AIME | 98.9% | 88.9% | GPT-6 Luna |
| FrontierMath, tiers 1 to 3 | 78.9% | Not measured | Only GPT-6 Luna measured |
| FrontierMath, tier 4 | 56.1% | Not measured | Only GPT-6 Luna measured |
| ProofBench | 64.0% | Not measured | Only GPT-6 Luna measured |
| LMArena Text: math | 1409 | 1389 | GPT-6 Luna |
| LMArena Text: mathematical work | 1427 | 1386 | GPT-6 Luna |
| Neither model has a result on the other 2 boards here | |||
KnowledgeLike-for-likePublic boards, shown as published, kept out of the index31
| Benchmark | GPT-6 Luna | gpt-oss-120b | Leader |
|---|---|---|---|
| MMLU Pro | Not measured | 79.2% | Only gpt-oss-120b measured |
| LegalBench (Vals AI) | Not measured | 75.9% | Only gpt-oss-120b measured |
| CaseLaw (Vals AI) | Not measured | 48.8% | Only gpt-oss-120b measured |
| CorpFin (Vals AI) | Not measured | 58.2% | Only gpt-oss-120b measured |
| TaxEval (Vals AI) | Not measured | 71.6% | Only gpt-oss-120b measured |
| MedQA (Vals AI) | Not measured | 91.4% | Only gpt-oss-120b measured |
| MedCode (Vals AI) | 44.7% | Not measured | Only GPT-6 Luna measured |
| MMLU Pro (Artificial Analysis run) | Not measured | 80.8% | Only gpt-oss-120b measured |
| SimpleQA Verified | 41.4% | Not measured | Only GPT-6 Luna measured |
| LMArena Text: science | 1386 | 1382 | GPT-6 Luna |
| LMArena Text: medicine and healthcare | 1352 | 1388 | gpt-oss-120b |
| LMArena Text: legal and government | 1400 | 1355 | GPT-6 Luna |
| LMArena Text: business and finance | 1388 | 1359 | GPT-6 Luna |
| Neither model has a result on the other 4 boards here | |||
Web designLike-for-likePublic boards, shown as published, kept out of the index60
| Benchmark | GPT-6 Luna | gpt-oss-120b | Leader |
|---|---|---|---|
| Design Arena: websites | 1272 | 968 | GPT-6 Luna |
| Design Arena: UI components | 1297 | 927 | GPT-6 Luna |
| Design Arena: game dev | 1259 | 992 | GPT-6 Luna |
| Design Arena: data viz | 1215 | 987 | GPT-6 Luna |
| Design Arena: 3D | 1217 | 901 | GPT-6 Luna |
| Design Arena: all code categories | 1271 | 963 | GPT-6 Luna |
| Design Arena: SVG | 1253 | Not measured | Only GPT-6 Luna measured |
| Design Arena: ASCII art | 1156 | Not measured | Only GPT-6 Luna measured |
| LiveBench design | 82.5% | Not measured | Only GPT-6 Luna measured |
GeneralLike-for-likePublic boards, shown as published, kept out of the index200
| Benchmark | GPT-6 Luna | gpt-oss-120b | Leader |
|---|---|---|---|
| Vals Index | 52.3% | Not measured | Only GPT-6 Luna measured |
| LiveBench data analysis | 73.4% | Not measured | Only GPT-6 Luna measured |
| Public Benefits Bench (Vals AI) | 57.6% | Not measured | Only GPT-6 Luna measured |
| SAGE (Vals AI) | 48.1% | Not measured | Only GPT-6 Luna measured |
| MedScribe (Vals AI) | 83.7% | Not measured | Only GPT-6 Luna measured |
| IFBench | Not measured | 69.0% | Only gpt-oss-120b measured |
| Long context reasoning (AA-LCR) | 83.3% | 52.0% | GPT-6 Luna |
| DTBench | 90.1% | 76.3% | GPT-6 Luna |
| LMCA | 44.5% | 22.1% | GPT-6 Luna |
| Fiction.LiveBench | Not measured | 44.4% | Only gpt-oss-120b measured |
| Creative writing (Lech Mazur) | Not measured | 77.1% | Only gpt-oss-120b measured |
| Surface Evolver Bench | Not measured | 25.0% | Only gpt-oss-120b measured |
| Furniture assembly | 44.2% | Not measured | Only GPT-6 Luna measured |
| LMArena Text | 1389 | 1366 | GPT-6 Luna |
| LMArena Text: instruction following | 1408 | 1318 | GPT-6 Luna |
| LMArena Text: creative writing | 1363 | 1274 | GPT-6 Luna |
| LMArena Vision | 1216 | Not measured | Only GPT-6 Luna measured |
| LMArena Text: English | 1393 | 1375 | GPT-6 Luna |
| LMArena Text: non-English | 1381 | 1351 | GPT-6 Luna |
| LMArena Text: Chinese | 1427 | 1385 | GPT-6 Luna |
| LMArena Text: German | 1376 | 1353 | GPT-6 Luna |
| LMArena Text: Japanese | 1369 | 1331 | GPT-6 Luna |
| LMArena Text: Korean | 1359 | 1282 | GPT-6 Luna |
| LMArena Text: French | 1408 | 1370 | GPT-6 Luna |
| LMArena Text: Spanish | 1391 | 1389 | GPT-6 Luna |
| LMArena Text: Russian | 1392 | 1343 | GPT-6 Luna |
| LMArena Text: Polish | 1383 | 1353 | GPT-6 Luna |
| LMArena Text: multi-turn | 1392 | 1340 | GPT-6 Luna |
| LMArena Text: longer queries | 1408 | 1319 | GPT-6 Luna |
| LMArena Text: writing and language | 1384 | 1306 | GPT-6 Luna |
| LMArena Text: entertainment and media | 1364 | 1292 | GPT-6 Luna |
| LMArena Vision: English | 1204 | Not measured | Only GPT-6 Luna measured |
| LMArena Vision: Chinese | 1266 | Not measured | Only GPT-6 Luna measured |
| LMArena Vision: reading text | 1225 | Not measured | Only GPT-6 Luna measured |
| LMArena Vision: creative writing | 1205 | Not measured | Only GPT-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
| Benchmark | GPT-6 Luna | gpt-oss-120b | 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 | OpenAI GPT-6 Luna | OpenAI gpt-oss-120b |
|---|---|---|
| Maker | OpenAI | OpenAI |
| Weights | No public weights listed | Open weights |
| Released | September 22, 2026 | August 5, 2025 |
| Context window | 1.05M | 131K |
| Input $/Mtok | $0.10 | $0.15 |
| Output $/Mtok | $0.50 | $0.60 |
| Coding index | 71.4 | 34.5 |
| Independent measurements behind it | 2 | 2 |
| Cost per solved task | Not computable | $0.51 |
| Source | OpenRouter listing | OpenRouter listing |
Questions
Is GPT-6 Luna better than gpt-oss-120b for coding?
Pick GPT-6 Luna for coding: it scores 71.4 on the Vibe Coding Index against 34.5 for gpt-oss-120b. Pick gpt-oss-120b when the benchmark that matters is LMArena Text: medicine and healthcare, where it leads.
Which is cheaper, GPT-6 Luna or gpt-oss-120b?
GPT-6 Luna costs $0.10 per million input tokens and $0.50 per million output tokens; gpt-oss-120b costs $0.15 and $0.60. Cost per solved task is known for gpt-oss-120b only.
Which has the bigger context window, GPT-6 Luna or gpt-oss-120b?
GPT-6 Luna, with 1.05M tokens against 131K.
How many benchmarks is the GPT-6 Luna vs gpt-oss-120b comparison based on?
46 benchmarks have a result for both models as of October 21, 2026. GPT-6 Luna's coding index rests on 2 independent benchmarks and gpt-oss-120b's on 2. Where only one model has a result, the page says so instead of naming a winner.