Model comparison
Claude Sonnet 5.5 vs Grok 4.5
Claude Sonnet 5.5 is the stronger model overall, scoring 61.9 to 55.0 on the Noometry Index.
Last verified . 28 shared benchmarks.
Summary
- They share 28 benchmarks with published results for both. Claude Sonnet 5.5 scores higher in 9 categories and Grok 4.5 in 1 category; 7 gaps are clear of the uncertainty.
- The widest gap is in math, where Claude Sonnet 5.5 leads 87.9 to 60.9.
- The biggest single-benchmark swing is ProofBench: 100% for Claude Sonnet 5.5 and 31% for Grok 4.5.
- Grok 4.5 is cheaper at $2 / $6 per million input/output tokens, against $2 / $10 for Claude Sonnet 5.5.
- Claude Sonnet 5.5 accepts more context: 1M tokens versus 500K.
Side by side
| Claude Sonnet 5.5 | Grok 4.5 | |
|---|---|---|
| Provider | Anthropic | xAI |
| Noometry Index | 61.9 | 55.0 |
| Released | 2026-09-28 | 2026-07-08 |
| Weights | Proprietary | Proprietary |
| Context window | 1M | 500K |
| Max output | 128K | 500K |
| Input $ / M tokens | $2 | $2 |
| Output $ / M tokens | $10 | $6 |
| Results tracked | 32 | 52 |
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Category by category
Coding Claude Sonnet 5.5 leads
Claude Sonnet 5.5: 67.3 (#6), Grok 4.5: 52.2 (#35)
| Benchmark | Claude Sonnet 5.5 | Grok 4.5 |
|---|---|---|
| FrontierCode | 52.1% | 42.4% |
| LMArena WebDev | 1774 | 1553 |
| SciCode | 61% | 54.1% |
| LMArena Coding | 1513 | 1474 |
| ALE-Bench | 1,819 | 1,309 |
| DeepSWE | — | 53.8% |
| CursorBench | 55.5% | — |
| FrontierSWE | 61.9% | — |
| WeirdML | — | 46.4% |
Agentic & Tool Use Too close to call
Claude Sonnet 5.5: 45.0 (#16), Grok 4.5: 44.4 (#17)
| Benchmark | Claude Sonnet 5.5 | Grok 4.5 |
|---|---|---|
| APEX-Agents | 75.5% | 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
Claude Sonnet 5.5: 54.0 (#28), Grok 4.5: 56.1 (#25)
| Benchmark | Claude Sonnet 5.5 | Grok 4.5 |
|---|---|---|
| NYT Connections (extended) | 80.5% | 79.9% |
| CritPt | 31.4% | 15.4% |
| LMArena Hard Prompts | 1495 | 1462 |
| Epoch Capabilities Index | 165.03 | 153.92 |
| ARC-AGI-2 | — | 52.6% |
| SimpleBench | — | 70% |
| Kagi LLM Benchmark | — | 83.5% |
| ARC-AGI-1 | — | 87.2% |
| Chess Puzzles | — | 36% |
| Mystery Game Puzzles | 65% | — |
| DTBench | — | 96.5% |
| LMCA | — | 45.2% |
| Surface Evolver Bench | — | 74.4% |
Math Claude Sonnet 5.5 leads
Claude Sonnet 5.5: 87.9 (#6), Grok 4.5: 60.9 (#35)
| Benchmark | Claude Sonnet 5.5 | Grok 4.5 |
|---|---|---|
| FrontierMath (Tiers 1-3) | 88.8% | 57.2% |
| FrontierMath Tier 4 | 80.5% | 24.4% |
| OTIS Mock AIME 2024-2025 | 100% | 97.8% |
| ProofBench | 100% | 31% |
| LMArena Math | 1510 | 1459 |
| FrontierMath Erdős | 2.9% | — |
Knowledge Claude Sonnet 5.5 leads
Claude Sonnet 5.5: 66.0 (#12), Grok 4.5: 62.3 (#24)
| Benchmark | Claude Sonnet 5.5 | Grok 4.5 |
|---|---|---|
| GPQA Diamond | 95.6% | 93.4% |
| SimpleQA Verified | 46.5% | 48.3% |
| LMArena Expert | 1540 | 1466 |
Multimodal Claude Sonnet 5.5 leads
Claude Sonnet 5.5: 51.5 (#6), Grok 4.5: 37.6 (#72)
| Benchmark | Claude Sonnet 5.5 | Grok 4.5 |
|---|---|---|
| LMArena Vision | 1289 | 1288 |
| Furniture Assembly | 75% | 22.5% |
| Blueprint-Bench 2 | — | 27.3% |
| LMArena Document | — | 1452 |
Multilingual Too close to call
Claude Sonnet 5.5: 55.3 (#30), Grok 4.5: 54.4 (#42)
| Benchmark | Claude Sonnet 5.5 | Grok 4.5 |
|---|---|---|
| LMArena Non-English | 1452 | 1440 |
| LMArena Chinese | 1522 | 1496 |
| LMArena Russian | 1451 | 1448 |
| LMArena French | — | 1456 |
| LMArena German | — | 1446 |
| LMArena Japanese | — | 1428 |
| LMArena Korean | — | 1404 |
| LMArena Spanish | — | 1450 |
Instruction Following Claude Sonnet 5.5 leads
Claude Sonnet 5.5: 78.3 (#11), Grok 4.5: 76.0 (#48)
| Benchmark | Claude Sonnet 5.5 | Grok 4.5 |
|---|---|---|
| LMArena Instruction Following | 1495 | 1446 |
Long Context Claude Sonnet 5.5 leads
Claude Sonnet 5.5: 45.9 (#28), Grok 4.5: 44.8 (#56)
| Benchmark | Claude Sonnet 5.5 | Grok 4.5 |
|---|---|---|
| LMArena Longer Query | 1498 | 1463 |
Writing & Preference Too close to call
Claude Sonnet 5.5: 66.0 (#40), Grok 4.5: 65.8 (#42)
| Benchmark | Claude Sonnet 5.5 | Grok 4.5 |
|---|---|---|
| LMArena Text | 1471 | 1448 |
| LMArena Creative Writing | 1465 | 1442 |
| LMArena Multi-Turn | 1474 | 1456 |
| EQ-Bench Creative Writing | — | 1579 |
Frequently asked questions
Is Claude Sonnet 5.5 better than Grok 4.5?
Claude Sonnet 5.5 is the stronger model overall, scoring 61.9 to 55.0 on the Noometry Index.
Which is cheaper, Claude Sonnet 5.5 or Grok 4.5?
Grok 4.5 is cheaper. It lists at $2 per million input tokens and $6 per million output tokens; Claude Sonnet 5.5 lists at $2 and $10.
Is Claude Sonnet 5.5 or Grok 4.5 better for coding?
Claude Sonnet 5.5 scores higher on coding benchmarks: 67.3 versus 52.2 in the Noometry coding category.
Which has the bigger context window?
Claude Sonnet 5.5 does, with 1M tokens against 500K.
How many benchmarks do Claude Sonnet 5.5 and Grok 4.5 share?
28 benchmarks have published results for both models. Claude Sonnet 5.5 has 32 scored results on Noometry and Grok 4.5 has 52.