Model comparison
GPT-5.6 Luna vs Grok 4.3
GPT-5.6 Luna is the stronger model overall, scoring 54.7 to 43.6 on the Noometry Index.
Last verified . 38 shared benchmarks.
Summary
- They share 38 benchmarks with published results for both. GPT-5.6 Luna scores higher in 10 categories and Grok 4.3 in 0 categories; 10 gaps are clear of the uncertainty.
- The widest gap is in math, where GPT-5.6 Luna leads 77.5 to 45.8.
- The biggest single-benchmark swing is ProofBench: 60% for GPT-5.6 Luna and 11% for Grok 4.3.
- GPT-5.6 Luna is cheaper at $0.20 / $1.20 per million input/output tokens, against $1.25 / $2.50 for Grok 4.3.
- GPT-5.6 Luna accepts more context: 1.05M tokens versus 1M.
Side by side
| GPT-5.6 Luna | Grok 4.3 | |
|---|---|---|
| Provider | OpenAI | xAI |
| Noometry Index | 54.7 | 43.6 |
| Released | 2026-07-09 | 2026-04-17 |
| Weights | Proprietary | Proprietary |
| Context window | 1.05M | 1M |
| Max output | 128K | 30K |
| Input $ / M tokens | $0.20 | $1.25 |
| Output $ / M tokens | $1.20 | $2.50 |
| Results tracked | 51 | 40 |
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Category by category
Coding GPT-5.6 Luna leads
GPT-5.6 Luna: 53.9 (#25), Grok 4.3: 41.3 (#117)
| Benchmark | GPT-5.6 Luna | Grok 4.3 |
|---|---|---|
| LMArena WebDev | 1517 | 1357 |
| SciCode | 53.6% | 47.3% |
| WeirdML | 60.9% | 49.9% |
| LMArena Coding | 1466 | 1415 |
| ALE-Bench | 1,667 | 944.17 |
| DeepSWE | 67.2% | — |
| FrontierCode | 39.8% | — |
| CursorBench | 35.9% | — |
Agentic & Tool Use GPT-5.6 Luna leads
GPT-5.6 Luna: 35.3 (#37), Grok 4.3: 27.6 (#93)
| Benchmark | GPT-5.6 Luna | Grok 4.3 |
|---|---|---|
| GDP.pdf | 22.7% | 8% |
| Vending-Bench 2 | 4,095 | 35.26 |
| BALROG | 45.6% | — |
| LMArena Search | — | 1165 |
Reasoning GPT-5.6 Luna leads
GPT-5.6 Luna: 47.5 (#38), Grok 4.3: 34.9 (#60)
| Benchmark | GPT-5.6 Luna | Grok 4.3 |
|---|---|---|
| NYT Connections (extended) | 69.4% | 55.2% |
| CritPt | 20.6% | 8% |
| Chess Puzzles | 40% | 25% |
| LMArena Hard Prompts | 1452 | 1397 |
| DTBench | 89.1% | 90.7% |
| LMCA | 48.5% | 38.3% |
| Epoch Capabilities Index | 156.32 | 149.13 |
| ARC-AGI-2 | 59.5% | — |
| SimpleBench | 46.8% | — |
| Kagi LLM Benchmark | 49.1% | — |
| ARC-AGI-1 | 88% | — |
| Mystery Game Puzzles | 21% | — |
| Surface Evolver Bench | 61.9% | — |
| ForecastBench | — | 60.3 |
Math GPT-5.6 Luna leads
GPT-5.6 Luna: 77.5 (#12), Grok 4.3: 45.8 (#60)
| Benchmark | GPT-5.6 Luna | Grok 4.3 |
|---|---|---|
| FrontierMath (Tiers 1-3) | 82.1% | 42.8% |
| FrontierMath Tier 4 | 61% | 14.6% |
| OTIS Mock AIME 2024-2025 | 98.3% | 93.3% |
| ProofBench | 60% | 11% |
| LMArena Math | 1455 | 1388 |
Knowledge GPT-5.6 Luna leads
GPT-5.6 Luna: 58.6 (#31), Grok 4.3: 52.5 (#57)
| Benchmark | GPT-5.6 Luna | Grok 4.3 |
|---|---|---|
| GPQA Diamond | 91.6% | 88.8% |
| SimpleQA Verified | 41% | 33.2% |
| LMArena Expert | 1479 | 1385 |
Multimodal GPT-5.6 Luna leads
GPT-5.6 Luna: 43.0 (#22), Grok 4.3: 31.6 (#96)
| Benchmark | GPT-5.6 Luna | Grok 4.3 |
|---|---|---|
| LMArena Vision | 1259 | 1231 |
| Blueprint-Bench 2 | 22.6% | 0% |
| Furniture Assembly | 42.5% | — |
| LMArena Document | 1457 | — |
Multilingual GPT-5.6 Luna leads
GPT-5.6 Luna: 53.0 (#73), Grok 4.3: 50.7 (#114)
| Benchmark | GPT-5.6 Luna | Grok 4.3 |
|---|---|---|
| LMArena Non-English | 1418 | 1385 |
| LMArena Chinese | 1469 | 1423 |
| LMArena French | 1457 | 1412 |
| LMArena German | 1459 | 1395 |
| LMArena Japanese | 1416 | 1379 |
| LMArena Korean | 1414 | 1357 |
| LMArena Russian | 1428 | 1399 |
| LMArena Spanish | 1445 | 1402 |
Instruction Following GPT-5.6 Luna leads
GPT-5.6 Luna: 76.0 (#48), Grok 4.3: 72.3 (#135)
| Benchmark | GPT-5.6 Luna | Grok 4.3 |
|---|---|---|
| LMArena Instruction Following | 1440 | 1366 |
Long Context GPT-5.6 Luna leads
GPT-5.6 Luna: 43.9 (#78), Grok 4.3: 42.5 (#118)
| Benchmark | GPT-5.6 Luna | Grok 4.3 |
|---|---|---|
| LMArena Longer Query | 1437 | 1393 |
Writing & Preference GPT-5.6 Luna leads
GPT-5.6 Luna: 68.3 (#27), Grok 4.3: 58.6 (#112)
| Benchmark | GPT-5.6 Luna | Grok 4.3 |
|---|---|---|
| LMArena Text | 1432 | 1397 |
| LMArena Creative Writing | 1397 | 1380 |
| EQ-Bench 4 | 1156 | 1075 |
| LMArena Multi-Turn | 1433 | 1406 |
| EQ-Bench Creative Writing | 1829 | — |
Frequently asked questions
Is GPT-5.6 Luna better than Grok 4.3?
GPT-5.6 Luna is the stronger model overall, scoring 54.7 to 43.6 on the Noometry Index.
Which is cheaper, GPT-5.6 Luna or Grok 4.3?
GPT-5.6 Luna is cheaper. It lists at $0.20 per million input tokens and $1.20 per million output tokens; Grok 4.3 lists at $1.25 and $2.50.
Is GPT-5.6 Luna or Grok 4.3 better for coding?
GPT-5.6 Luna scores higher on coding benchmarks: 53.9 versus 41.3 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 GPT-5.6 Luna and Grok 4.3 share?
38 benchmarks have published results for both models. GPT-5.6 Luna has 51 scored results on Noometry and Grok 4.3 has 40.