Model comparison
GPT-6 Luna vs Grok 4.5
Grok 4.5 is the stronger model overall, scoring 55.0 to 45.1 on the Noometry Index. GPT-6 Luna costs 15× less per token, which makes it the better buy when Grok 4.5's lead doesn't matter for your workload.
Last verified . 18 shared benchmarks.
Summary
- They share 18 benchmarks with published results for both. GPT-6 Luna scores higher in 2 categories and Grok 4.5 in 7 categories; 9 gaps are clear of the uncertainty.
- The widest gap is in math, where Grok 4.5 leads 60.7 to 35.6.
- The biggest single-benchmark swing is Furniture Assembly: 44.2% for GPT-6 Luna and 22.5% for Grok 4.5.
- GPT-6 Luna is cheaper at $0.10 / $0.50 per million input/output tokens, against $2 / $6 for Grok 4.5.
- GPT-6 Luna accepts more context: 1.05M tokens versus 500K.
Side by side
| GPT-6 Luna | Grok 4.5 | |
|---|---|---|
| Provider | OpenAI | xAI |
| Noometry Index | 45.1 | 55.0 |
| Released | 2026-09-22 | 2026-07-08 |
| Weights | Proprietary | Proprietary |
| Context window | 1.05M | 500K |
| Max output | 128K | 500K |
| Input $ / M tokens | $0.10 | $2 |
| Output $ / M tokens | $0.50 | $6 |
| Results tracked | 18 | 52 |
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Category by category
Coding GPT-6 Luna leads
GPT-6 Luna: 54.7 (#24), Grok 4.5: 51.7 (#34)
| Benchmark | GPT-6 Luna | Grok 4.5 |
|---|---|---|
| DeepSWE | 66.6% | 53.8% |
| FrontierCode | 42.4% | 42.4% |
| LMArena WebDev | 1583 | 1552 |
| LMArena Coding | 1448 | 1473 |
| SciCode | — | 54.1% |
| WeirdML | — | 46.4% |
| ALE-Bench | — | 1,309 |
Agentic & Tool Use Not comparable
GPT-6 Luna: —, Grok 4.5: 44.4 (#15)
| Benchmark | GPT-6 Luna | Grok 4.5 |
|---|---|---|
| APEX-Agents | — | 56.2% |
| τ²-bench Banking | — | 47.9% |
| PostTrainBench | — | 23.4% |
| GBAEval | — | 65.4% |
| GDP.pdf | — | 14% |
| LMArena Search | — | 1213 |
| Vending-Bench 2 | — | 3,887 |
Reasoning Grok 4.5 leads
GPT-6 Luna: 31.7 (#68), Grok 4.5: 56.0 (#23)
| Benchmark | GPT-6 Luna | Grok 4.5 |
|---|---|---|
| NYT Connections (extended) | 68.7% | 79.9% |
| LMArena Hard Prompts | 1415 | 1462 |
| ARC-AGI-2 | — | 52.6% |
| SimpleBench | — | 70% |
| Kagi LLM Benchmark | — | 83.5% |
| ARC-AGI-1 | — | 87.2% |
| CritPt | — | 15.4% |
| Chess Puzzles | — | 36% |
| DTBench | — | 96.5% |
| LMCA | — | 45.2% |
| Surface Evolver Bench | — | 74.4% |
| Epoch Capabilities Index | — | 154.02 |
Math Grok 4.5 leads
GPT-6 Luna: 35.6 (#140), Grok 4.5: 60.7 (#29)
| Benchmark | GPT-6 Luna | Grok 4.5 |
|---|---|---|
| LMArena Math | 1396 | 1457 |
| FrontierMath (Tiers 1-3) | — | 57.2% |
| FrontierMath Tier 4 | — | 24.4% |
| OTIS Mock AIME 2024-2025 | — | 97.8% |
| ProofBench | — | 31% |
Knowledge Grok 4.5 leads
GPT-6 Luna: 40.1 (#110), Grok 4.5: 62.3 (#21)
| Benchmark | GPT-6 Luna | Grok 4.5 |
|---|---|---|
| LMArena Expert | 1458 | 1466 |
| GPQA Diamond | — | 93.4% |
| SimpleQA Verified | — | 48.3% |
Multimodal GPT-6 Luna leads
GPT-6 Luna: 42.0 (#27), Grok 4.5: 37.8 (#63)
| Benchmark | GPT-6 Luna | Grok 4.5 |
|---|---|---|
| Furniture Assembly | 44.2% | 22.5% |
| LMArena Vision | — | 1287 |
| Blueprint-Bench 2 | — | 27.3% |
| LMArena Document | — | 1452 |
Multilingual Grok 4.5 leads
GPT-6 Luna: 51.0 (#111), Grok 4.5: 54.5 (#43)
| Benchmark | GPT-6 Luna | Grok 4.5 |
|---|---|---|
| LMArena Non-English | 1390 | 1439 |
| LMArena Chinese | 1425 | 1497 |
| LMArena Russian | 1392 | 1447 |
| LMArena Spanish | 1416 | 1452 |
| LMArena French | — | 1458 |
| LMArena German | — | 1448 |
| LMArena Japanese | — | 1425 |
| LMArena Korean | — | 1402 |
Instruction Following Grok 4.5 leads
GPT-6 Luna: 74.7 (#85), Grok 4.5: 76.3 (#45)
| Benchmark | GPT-6 Luna | Grok 4.5 |
|---|---|---|
| LMArena Instruction Following | 1414 | 1446 |
Long Context Grok 4.5 leads
GPT-6 Luna: 43.3 (#95), Grok 4.5: 44.8 (#54)
| Benchmark | GPT-6 Luna | Grok 4.5 |
|---|---|---|
| LMArena Longer Query | 1417 | 1463 |
Writing & Preference Grok 4.5 leads
GPT-6 Luna: 58.4 (#115), Grok 4.5: 65.9 (#40)
| Benchmark | GPT-6 Luna | Grok 4.5 |
|---|---|---|
| LMArena Text | 1392 | 1448 |
| LMArena Creative Writing | 1357 | 1442 |
| LMArena Multi-Turn | 1400 | 1457 |
| EQ-Bench Creative Writing | — | 1579 |
Frequently asked questions
Is GPT-6 Luna better than Grok 4.5?
Grok 4.5 is the stronger model overall, scoring 55.0 to 45.1 on the Noometry Index. GPT-6 Luna costs 15× less per token, which makes it the better buy when Grok 4.5's lead doesn't matter for your workload.
Which is cheaper, GPT-6 Luna or Grok 4.5?
GPT-6 Luna is cheaper. It lists at $0.10 per million input tokens and $0.50 per million output tokens; Grok 4.5 lists at $2 and $6.
Is GPT-6 Luna or Grok 4.5 better for coding?
GPT-6 Luna scores higher on coding benchmarks: 54.7 versus 51.7 in the Noometry coding category.
Which has the bigger context window?
GPT-6 Luna does, with 1.05M tokens against 500K.
How many benchmarks do GPT-6 Luna and Grok 4.5 share?
18 benchmarks have published results for both models. GPT-6 Luna has 18 scored results on Noometry and Grok 4.5 has 52.