GPT-5.6 Sol Pro vs GPT-6 Luna
GPT-6 Luna costs 40.0x less per output token than GPT-5.6 Sol Pro ($0.50 vs $20.00 per million). Updated October 22, 2026; 5 benchmarks have a result for both.
vs boards won of 5 shared
GPT-5.6 Sol Pro or GPT-6 Luna: which to pick
Only GPT-6 Luna has a coding score, 57.3 on the Vibe Coding Index; GPT-5.6 Sol Pro has none, so the two cannot be ranked on coding.
Pick GPT-5.6 Sol Pro for work measured by APEX-Agents or Chess puzzles, where it leads.
Model AGPT-5.6 Sol ProOpenAINot benchmarkedNo coding benchmarkNo cost per solved taskModel BGPT-6 LunaOpenAI57.3/1005 independent benchmarksNo cost per solved task
- Shared results
- 5
- GPT-5.6 Sol Pro only
- 2
- GPT-6 Luna only
- 98
- Like-for-like categories
- 4 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
Only GPT-6 Luna has a coding score, so no call is made.
One side not measured
Intelligence
AA Intelligence Index
No call
Only GPT-6 Luna has a AA Intelligence Index result, 38.1.
Directional only
Web design
Design Arena: websites
No call
Only GPT-6 Luna has a Design Arena: websites result, 1271.
Directional only
General
Vals Index
No call
Only GPT-6 Luna has a Vals Index result, 52.3%.
Directional only
Long documents
Listed context window
No call
Both take 1.05M tokens.
Listed by OpenRouter
Everyday cost
1K input + 500 output tokens
GPT-6 Luna
GPT-5.6 Sol Pro $0.014, GPT-6 Luna $0.0003 per turn.
List prices
At a glance
- Coding index
- GPT-5.6 Sol Pro not benchmarked, GPT-6 Luna 57.3 from 5 benchmarks.
- Widest category
- Reasoning, 32.0 points apart on average over 1 shared benchmark.
- Widest single gap
- Chess puzzles: GPT-5.6 Sol Pro 68.0% against GPT-6 Luna 36.0%, 32.0 points apart on a 0 to 100 scale.
- Output price
- GPT-5.6 Sol Pro $20.00 against GPT-6 Luna $0.50 per million output tokens, 40.0x apart.
- Context window
- Both take 1.05M tokens.
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-5.6 Sol Pro | Bars | GPT-6 Luna | Ties |
|---|---|---|---|---|
| Agentic work | 1 | 0 | ||
| Reasoning | 1 | 0 | ||
| Math | 1 | 0 | ||
| General | 2 | 0 | ||
| All shared boards | 5 | 0 |
CodingDirectional onlySix of these boards feed the Vibe Coding Index19 boards, none shared
| Benchmark | GPT-5.6 Sol Pro | GPT-6 Luna | Leader |
|---|---|---|---|
| LiveBench coding | Not measured | 84.5% | Only GPT-6 Luna measured |
| LMArena WebDev | Not measured | 1578 | Only GPT-6 Luna measured |
| Terminal-Bench 4 (Vals AI) | Not measured | 13.6% | Only GPT-6 Luna measured |
| Vibe Code Bench (Vals AI) | Not measured | 81.7% | Only GPT-6 Luna measured |
| 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 |
| FrontierCode | Not measured | 42.4% | Only GPT-6 Luna measured |
| WeirdML | 89.4% | Not measured | Only GPT-5.6 Sol Pro measured |
| ALE-Bench | Not measured | 1576.9 | Only GPT-6 Luna measured |
| LMArena Text: coding | Not measured | 1437 | Only GPT-6 Luna measured |
| LMArena Text: software and IT | Not measured | 1423 | Only GPT-6 Luna measured |
| LMArena WebDev: React | Not measured | 1573 | Only GPT-6 Luna measured |
| LMArena WebDev: HTML | Not measured | 1595 | Only GPT-6 Luna measured |
| LMArena WebDev: from an image | Not measured | 1571 | Only GPT-6 Luna measured |
| Neither model has a result on the other 20 boards here | |||
IntelligenceDirectional onlyPublic boards, shown as published, kept out of the index2 boards, none shared
| Benchmark | GPT-5.6 Sol Pro | GPT-6 Luna | Leader |
|---|---|---|---|
| AA Intelligence Index | Not measured | 38.1 | Only GPT-6 Luna measured |
| Epoch Capabilities Index | Not measured | 156.8 | Only GPT-6 Luna measured |
Agentic workLike-for-likePublic boards, shown as published, kept out of the index10
| Benchmark | GPT-5.6 Sol Pro | GPT-6 Luna | Leader |
|---|---|---|---|
| Design Arena: agents building web apps | Not measured | 1191 | Only GPT-6 Luna measured |
| Design Arena: agents building full-stack apps | Not measured | 1158 | Only GPT-6 Luna measured |
| Design Arena: agents building mobile apps | Not measured | 1134 | Only GPT-6 Luna measured |
| 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 | 51.4% | 44.3% | GPT-5.6 Sol Pro |
| SpireClimb | Not measured | 0.0% | Only GPT-6 Luna measured |
| Neither model has a result on the other 24 boards here | |||
ReasoningLike-for-likePublic boards, shown as published, kept out of the index10
| Benchmark | GPT-5.6 Sol Pro | GPT-6 Luna | Leader |
|---|---|---|---|
| LiveBench reasoning | Not measured | 81.8% | Only GPT-6 Luna measured |
| MysteryMechanism (Vals AI) | Not measured | 19.4% | Only GPT-6 Luna measured |
| Humanity's Last Exam (Artificial Analysis run) | Not measured | 38.5% | Only GPT-6 Luna measured |
| GPQA Diamond (Epoch AI run) | Not measured | 90.5% | Only GPT-6 Luna measured |
| ARC-AGI | Not measured | 86.7% | Only GPT-6 Luna measured |
| ARC-AGI-2 | Not measured | 59.3% | Only GPT-6 Luna measured |
| SimpleBench | 71.7% | Not measured | Only GPT-5.6 Sol Pro measured |
| Chess puzzles | 68.0% | 36.0% | GPT-5.6 Sol Pro |
| Mystery game puzzles | Not measured | 7.0% | Only GPT-6 Luna measured |
| LMArena Text: hard prompts | Not measured | 1410 | Only GPT-6 Luna measured |
| LMArena Text: expert | Not measured | 1442 | Only GPT-6 Luna measured |
| LMArena Text: hard prompts in English | Not measured | 1410 | Only GPT-6 Luna measured |
| 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 8 boards here | |||
MathLike-for-likePublic boards, shown as published, kept out of the index10
| Benchmark | GPT-5.6 Sol Pro | GPT-6 Luna | Leader |
|---|---|---|---|
| OTIS Mock AIME | Not measured | 98.9% | Only GPT-6 Luna measured |
| FrontierMath, tiers 1 to 3 | Not measured | 78.9% | Only GPT-6 Luna measured |
| FrontierMath, tier 4 | 80.5% | 56.1% | GPT-5.6 Sol Pro |
| ProofBench | Not measured | 64.0% | Only GPT-6 Luna measured |
| LMArena Text: math | Not measured | 1409 | Only GPT-6 Luna measured |
| LMArena Text: mathematical work | Not measured | 1427 | Only GPT-6 Luna measured |
| Neither model has a result on the other 7 boards here | |||
KnowledgeDirectional onlyPublic boards, shown as published, kept out of the index7 boards, none shared
| Benchmark | GPT-5.6 Sol Pro | GPT-6 Luna | Leader |
|---|---|---|---|
| MedCode (Vals AI) | Not measured | 44.7% | Only GPT-6 Luna measured |
| SimpleQA Verified | Not measured | 41.4% | Only GPT-6 Luna measured |
| LMArena Text: science | Not measured | 1386 | Only GPT-6 Luna measured |
| LMArena Text: medicine and healthcare | Not measured | 1352 | Only GPT-6 Luna measured |
| LMArena Text: legal and government | Not measured | 1400 | Only GPT-6 Luna measured |
| LMArena Text: business and finance | Not measured | 1388 | Only GPT-6 Luna measured |
| FACTS Benchmark Suite | Not measured | 63.3% | Only GPT-6 Luna measured |
| Neither model has a result on the other 11 boards here | |||
Web designDirectional onlyPublic boards, shown as published, kept out of the index9 boards, none shared
| Benchmark | GPT-5.6 Sol Pro | GPT-6 Luna | Leader |
|---|---|---|---|
| Design Arena: websites | Not measured | 1271 | Only GPT-6 Luna measured |
| Design Arena: UI components | Not measured | 1295 | Only GPT-6 Luna measured |
| Design Arena: game dev | Not measured | 1257 | Only GPT-6 Luna measured |
| Design Arena: data viz | Not measured | 1216 | Only GPT-6 Luna measured |
| Design Arena: 3D | Not measured | 1218 | Only GPT-6 Luna measured |
| Design Arena: all code categories | Not measured | 1270 | Only GPT-6 Luna measured |
| Design Arena: SVG | Not measured | 1252 | Only GPT-6 Luna measured |
| Design Arena: ASCII art | Not measured | 1153 | Only GPT-6 Luna measured |
| LiveBench design | Not measured | 82.5% | Only GPT-6 Luna measured |
GeneralLike-for-likePublic boards, shown as published, kept out of the index20
| Benchmark | GPT-5.6 Sol Pro | 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) | Not measured | 48.1% | Only GPT-6 Luna measured |
| MedScribe (Vals AI) | Not measured | 83.7% | Only GPT-6 Luna measured |
| Long context reasoning (AA-LCR) | Not measured | 83.3% | Only GPT-6 Luna measured |
| DTBench | 96.0% | 90.1% | GPT-5.6 Sol Pro |
| LMCA | 59.2% | 44.5% | GPT-5.6 Sol Pro |
| Furniture assembly | Not measured | 44.2% | Only GPT-6 Luna measured |
| LMArena Text | Not measured | 1389 | Only GPT-6 Luna measured |
| LMArena Text: instruction following | Not measured | 1408 | Only GPT-6 Luna measured |
| LMArena Text: creative writing | Not measured | 1363 | Only GPT-6 Luna measured |
| LMArena Vision | Not measured | 1216 | Only GPT-6 Luna measured |
| LMArena Text: English | Not measured | 1393 | Only GPT-6 Luna measured |
| LMArena Text: non-English | Not measured | 1381 | Only GPT-6 Luna measured |
| LMArena Text: Chinese | Not measured | 1427 | Only GPT-6 Luna measured |
| LMArena Text: German | Not measured | 1376 | Only GPT-6 Luna measured |
| LMArena Text: Japanese | Not measured | 1369 | Only GPT-6 Luna measured |
| LMArena Text: Korean | Not measured | 1359 | Only GPT-6 Luna measured |
| LMArena Text: French | Not measured | 1408 | Only GPT-6 Luna measured |
| LMArena Text: Spanish | Not measured | 1391 | Only GPT-6 Luna measured |
| LMArena Text: Russian | Not measured | 1392 | Only GPT-6 Luna measured |
| LMArena Text: Polish | Not measured | 1383 | Only GPT-6 Luna measured |
| LMArena Text: multi-turn | Not measured | 1392 | Only GPT-6 Luna measured |
| LMArena Text: longer queries | Not measured | 1408 | Only GPT-6 Luna measured |
| LMArena Text: writing and language | Not measured | 1384 | Only GPT-6 Luna measured |
| LMArena Text: entertainment and media | Not measured | 1364 | Only GPT-6 Luna measured |
| 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 |
| Neither model has a result on the other 15 boards here | |||
Image generationNot comparablePublic boards, shown as published, kept out of the index0 boards, none shared
| Benchmark | GPT-5.6 Sol Pro | 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-5.6 Sol Pro$0.014Fits in one request
GPT-6 Luna$0.0003Fits in one request
GPT-6 Luna costs less
Repository review
50K input + 3K output tokens
GPT-5.6 Sol Pro$0.260Fits in one request
GPT-6 Luna$0.0065Fits in one request
GPT-6 Luna costs less
Agent loop
200K input + 10K output tokens
GPT-5.6 Sol Pro$1.00Fits in one request
GPT-6 Luna$0.025Fits in one request
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-5.6 Sol Pro | OpenAI GPT-6 Luna |
|---|---|---|
| Maker | OpenAI | OpenAI |
| Weights | No public weights listed | No public weights listed |
| Released | July 9, 2026 | September 22, 2026 |
| Context window | 1.05M | 1.05M |
| Input $/Mtok | $4.00 | $0.10 |
| Output $/Mtok | $20.00 | $0.50 |
| Coding index | Not benchmarked | 57.3 |
| Independent measurements behind it | 0 | 5 |
| Cost per solved task | Not computable | Not computable |
| Source | OpenRouter listing | OpenRouter listing |
Questions
Is GPT-5.6 Sol Pro better than GPT-6 Luna for coding?
Only GPT-6 Luna has a coding score, 57.3 on the Vibe Coding Index; GPT-5.6 Sol Pro has none, so the two cannot be ranked on coding. Pick GPT-5.6 Sol Pro for work measured by APEX-Agents or Chess puzzles, where it leads.
Which is cheaper, GPT-5.6 Sol Pro or GPT-6 Luna?
GPT-5.6 Sol Pro costs $4.00 per million input tokens and $20.00 per million output tokens; GPT-6 Luna costs $0.10 and $0.50. Cost per solved task is known for neither of them.
Which has the bigger context window, GPT-5.6 Sol Pro or GPT-6 Luna?
Neither: both take 1.05M tokens.
How many benchmarks is the GPT-5.6 Sol Pro vs GPT-6 Luna comparison based on?
5 benchmarks have a result for both models as of October 22, 2026. GPT-5.6 Sol Pro's coding index rests on 0 independent benchmarks and GPT-6 Luna's on 5. Where only one model has a result, the page says so instead of naming a winner.