Model comparison
Claude Sonnet 5.5 vs GPT-5.6 Luna
Claude Sonnet 5.5 is the stronger model overall, scoring 61.9 to 54.6 on the Noometry Index. GPT-5.6 Luna costs 8.9× less per token, which makes it the better buy when Claude Sonnet 5.5's lead doesn't matter for your workload.
Last verified . 30 shared benchmarks.
Summary
- They share 30 benchmarks with published results for both. Claude Sonnet 5.5 scores higher in 9 categories and GPT-5.6 Luna in 1 category; 10 gaps are clear of the uncertainty.
- The widest gap is in coding, where Claude Sonnet 5.5 leads 67.3 to 54.5.
- The biggest single-benchmark swing is Mystery Game Puzzles: 65% for Claude Sonnet 5.5 and 21% for GPT-5.6 Luna.
- GPT-5.6 Luna is cheaper at $0.20 / $1.20 per million input/output tokens, against $2 / $10 for Claude Sonnet 5.5.
- GPT-5.6 Luna accepts more context: 1.05M tokens versus 1M.
Side by side
| Claude Sonnet 5.5 | GPT-5.6 Luna | |
|---|---|---|
| Provider | Anthropic | OpenAI |
| Noometry Index | 61.9 | 54.6 |
| Released | 2026-09-28 | 2026-07-09 |
| Weights | Proprietary | Proprietary |
| Context window | 1M | 1.05M |
| Max output | 128K | 128K |
| Input $ / M tokens | $2 | $0.20 |
| Output $ / M tokens | $10 | $1.20 |
| Results tracked | 32 | 52 |
Sponsored placements are available on pages like this one. Advertise on Noometry
Category by category
Coding Claude Sonnet 5.5 leads
Claude Sonnet 5.5: 67.3 (#6), GPT-5.6 Luna: 54.5 (#28)
| Benchmark | Claude Sonnet 5.5 | GPT-5.6 Luna |
|---|---|---|
| FrontierCode | 52.1% | 39.8% |
| CursorBench | 55.5% | 35.9% |
| LMArena WebDev | 1774 | 1519 |
| SciCode | 61% | 53.6% |
| LMArena Coding | 1513 | 1466 |
| ALE-Bench | 1,819 | 1,667 |
| DeepSWE | — | 67.2% |
| FrontierSWE | 61.9% | — |
| WeirdML | — | 60.9% |
Agentic & Tool Use Claude Sonnet 5.5 leads
Claude Sonnet 5.5: 45.0 (#16), GPT-5.6 Luna: 34.4 (#45)
| Benchmark | Claude Sonnet 5.5 | GPT-5.6 Luna |
|---|---|---|
| APEX-Agents | 75.5% | 43% |
| BALROG | — | 45.6% |
| GDP.pdf | — | 22.7% |
| Vending-Bench 2 | — | 4,095 |
Reasoning Claude Sonnet 5.5 leads
Claude Sonnet 5.5: 54.0 (#28), GPT-5.6 Luna: 47.6 (#43)
| Benchmark | Claude Sonnet 5.5 | GPT-5.6 Luna |
|---|---|---|
| NYT Connections (extended) | 80.5% | 69.4% |
| CritPt | 31.4% | 20.6% |
| LMArena Hard Prompts | 1495 | 1451 |
| Mystery Game Puzzles | 65% | 21% |
| Epoch Capabilities Index | 165.03 | 156.39 |
| ARC-AGI-2 | — | 59.5% |
| SimpleBench | — | 46.8% |
| Kagi LLM Benchmark | — | 49.1% |
| ARC-AGI-1 | — | 88% |
| Chess Puzzles | — | 40% |
| DTBench | — | 89.1% |
| LMCA | — | 48.5% |
| Surface Evolver Bench | — | 61.9% |
Math Claude Sonnet 5.5 leads
Claude Sonnet 5.5: 87.9 (#6), GPT-5.6 Luna: 77.7 (#14)
| Benchmark | Claude Sonnet 5.5 | GPT-5.6 Luna |
|---|---|---|
| FrontierMath (Tiers 1-3) | 88.8% | 82.1% |
| FrontierMath Tier 4 | 80.5% | 61% |
| OTIS Mock AIME 2024-2025 | 100% | 98.3% |
| ProofBench | 100% | 60% |
| LMArena Math | 1510 | 1458 |
| FrontierMath Erdős | 2.9% | — |
Knowledge Claude Sonnet 5.5 leads
Claude Sonnet 5.5: 66.0 (#12), GPT-5.6 Luna: 58.5 (#34)
| Benchmark | Claude Sonnet 5.5 | GPT-5.6 Luna |
|---|---|---|
| GPQA Diamond | 95.6% | 91.6% |
| SimpleQA Verified | 46.5% | 41% |
| LMArena Expert | 1540 | 1478 |
Multimodal Claude Sonnet 5.5 leads
Claude Sonnet 5.5: 51.5 (#6), GPT-5.6 Luna: 42.7 (#28)
| Benchmark | Claude Sonnet 5.5 | GPT-5.6 Luna |
|---|---|---|
| LMArena Vision | 1289 | 1258 |
| Furniture Assembly | 75% | 42.5% |
| Blueprint-Bench 2 | — | 22.6% |
| LMArena Document | — | 1457 |
Multilingual Claude Sonnet 5.5 leads
Claude Sonnet 5.5: 55.3 (#30), GPT-5.6 Luna: 52.8 (#78)
| Benchmark | Claude Sonnet 5.5 | GPT-5.6 Luna |
|---|---|---|
| LMArena Non-English | 1452 | 1417 |
| LMArena Chinese | 1522 | 1470 |
| LMArena Russian | 1451 | 1428 |
| LMArena French | — | 1456 |
| LMArena German | — | 1454 |
| LMArena Japanese | — | 1411 |
| LMArena Korean | — | 1415 |
| LMArena Spanish | — | 1448 |
Instruction Following Claude Sonnet 5.5 leads
Claude Sonnet 5.5: 78.3 (#11), GPT-5.6 Luna: 75.6 (#57)
| Benchmark | Claude Sonnet 5.5 | GPT-5.6 Luna |
|---|---|---|
| LMArena Instruction Following | 1495 | 1437 |
Long Context Claude Sonnet 5.5 leads
Claude Sonnet 5.5: 45.9 (#28), GPT-5.6 Luna: 43.9 (#82)
| Benchmark | Claude Sonnet 5.5 | GPT-5.6 Luna |
|---|---|---|
| LMArena Longer Query | 1498 | 1436 |
Writing & Preference GPT-5.6 Luna leads
Claude Sonnet 5.5: 66.0 (#40), GPT-5.6 Luna: 68.0 (#29)
| Benchmark | Claude Sonnet 5.5 | GPT-5.6 Luna |
|---|---|---|
| LMArena Text | 1471 | 1431 |
| LMArena Creative Writing | 1465 | 1396 |
| LMArena Multi-Turn | 1474 | 1434 |
| EQ-Bench Creative Writing | — | 1829 |
| EQ-Bench 4 | — | 1156 |
Frequently asked questions
Is Claude Sonnet 5.5 better than GPT-5.6 Luna?
Claude Sonnet 5.5 is the stronger model overall, scoring 61.9 to 54.6 on the Noometry Index. GPT-5.6 Luna costs 8.9× less per token, which makes it the better buy when Claude Sonnet 5.5's lead doesn't matter for your workload.
Which is cheaper, Claude Sonnet 5.5 or GPT-5.6 Luna?
GPT-5.6 Luna is cheaper. It lists at $0.20 per million input tokens and $1.20 per million output tokens; Claude Sonnet 5.5 lists at $2 and $10.
Is Claude Sonnet 5.5 or GPT-5.6 Luna better for coding?
Claude Sonnet 5.5 scores higher on coding benchmarks: 67.3 versus 54.5 in the Noometry coding category.
Which has the bigger context window?
GPT-5.6 Luna does, with 1.05M tokens against 1M.
How many benchmarks do Claude Sonnet 5.5 and GPT-5.6 Luna share?
30 benchmarks have published results for both models. Claude Sonnet 5.5 has 32 scored results on Noometry and GPT-5.6 Luna has 52.