Model comparison
Claude Sonnet 5.5 vs Grok 4.20 (Non-Reasoning)
Claude Sonnet 5.5 is the stronger model overall, scoring 61.9 to 48.6 on the Noometry Index. Grok 4.20 (Non-Reasoning) costs 2.6× less per token, which makes it the better buy when Claude Sonnet 5.5's lead doesn't matter for your workload.
Last verified . 23 shared benchmarks.
Summary
- They share 23 benchmarks with published results for both. Claude Sonnet 5.5 scores higher in 10 categories and Grok 4.20 (Non-Reasoning) in 0 categories; 7 gaps are clear of the uncertainty.
- The widest gap is in math, where Claude Sonnet 5.5 leads 87.9 to 48.2.
- The biggest single-benchmark swing is ProofBench: 100% for Claude Sonnet 5.5 and 14% for Grok 4.20 (Non-Reasoning).
- Grok 4.20 (Non-Reasoning) is cheaper at $1.25 / $2.50 per million input/output tokens, against $2 / $10 for Claude Sonnet 5.5.
Side by side
| Claude Sonnet 5.5 | Grok 4.20 (Non-Reasoning) | |
|---|---|---|
| Provider | Anthropic | xAI |
| Noometry Index | 61.9 | 48.6 |
| Released | 2026-09-28 | 2026-02-17 |
| Weights | Proprietary | Proprietary |
| Context window | 1M | 1M |
| Max output | 128K | 30K |
| Input $ / M tokens | $2 | $1.25 |
| Output $ / M tokens | $10 | $2.50 |
| Results tracked | 32 | 46 |
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Category by category
Coding Claude Sonnet 5.5 leads
Claude Sonnet 5.5: 67.3 (#6), Grok 4.20 (Non-Reasoning): 42.1 (#112)
| Benchmark | Claude Sonnet 5.5 | Grok 4.20 (Non-Reasoning) |
|---|---|---|
| LMArena WebDev | 1774 | 1375 |
| LMArena Coding | 1513 | 1459 |
| ALE-Bench | 1,819 | 1,150 |
| FrontierCode | 52.1% | — |
| CursorBench | 55.5% | — |
| FrontierSWE | 61.9% | — |
| SciCode | 61% | — |
| WeirdML | — | 52.3% |
Agentic & Tool Use Claude Sonnet 5.5 leads
Claude Sonnet 5.5: 45.0 (#16), Grok 4.20 (Non-Reasoning): 34.4 (#46)
| Benchmark | Claude Sonnet 5.5 | Grok 4.20 (Non-Reasoning) |
|---|---|---|
| Terminal-Bench | — | 57.3% |
| APEX-Agents | 75.5% | — |
| τ²-bench Banking | — | 18% |
| LMArena Search | — | 1189 |
| Vending-Bench 2 | — | 4,663 |
Reasoning Claude Sonnet 5.5 leads
Claude Sonnet 5.5: 54.0 (#28), Grok 4.20 (Non-Reasoning): 52.3 (#32)
| Benchmark | Claude Sonnet 5.5 | Grok 4.20 (Non-Reasoning) |
|---|---|---|
| NYT Connections (extended) | 80.5% | 85.4% |
| LMArena Hard Prompts | 1495 | 1451 |
| Epoch Capabilities Index | 165.03 | 151.98 |
| ARC-AGI-2 | — | 65.1% |
| Kagi LLM Benchmark | — | 75% |
| ARC-AGI-1 | — | 89.5% |
| CritPt | 31.4% | — |
| Chess Puzzles | — | 24% |
| Thematic Generalization | — | 63.8% |
| Mystery Game Puzzles | 65% | — |
| DTBench | — | 90.1% |
| LMCA | — | 38.7% |
| ForecastBench | — | 61.4 |
Math Claude Sonnet 5.5 leads
Claude Sonnet 5.5: 87.9 (#6), Grok 4.20 (Non-Reasoning): 48.2 (#65)
| Benchmark | Claude Sonnet 5.5 | Grok 4.20 (Non-Reasoning) |
|---|---|---|
| FrontierMath (Tiers 1-3) | 88.8% | 44.9% |
| FrontierMath Tier 4 | 80.5% | 17.1% |
| OTIS Mock AIME 2024-2025 | 100% | 92.2% |
| ProofBench | 100% | 14% |
| LMArena Math | 1510 | 1455 |
| FrontierMath Erdős | 2.9% | — |
Knowledge Claude Sonnet 5.5 leads
Claude Sonnet 5.5: 66.0 (#12), Grok 4.20 (Non-Reasoning): 52.8 (#60)
| Benchmark | Claude Sonnet 5.5 | Grok 4.20 (Non-Reasoning) |
|---|---|---|
| GPQA Diamond | 95.6% | 89.3% |
| SimpleQA Verified | 46.5% | 30.2% |
| LMArena Expert | 1540 | 1439 |
Multimodal Claude Sonnet 5.5 leads
Claude Sonnet 5.5: 51.5 (#6), Grok 4.20 (Non-Reasoning): 33.3 (#98)
| Benchmark | Claude Sonnet 5.5 | Grok 4.20 (Non-Reasoning) |
|---|---|---|
| LMArena Vision | 1289 | 1263 |
| Blueprint-Bench 2 | — | 0% |
| Furniture Assembly | 75% | — |
| LMArena Document | — | 1416 |
Multilingual Too close to call
Claude Sonnet 5.5: 55.3 (#30), Grok 4.20 (Non-Reasoning): 54.5 (#40)
| Benchmark | Claude Sonnet 5.5 | Grok 4.20 (Non-Reasoning) |
|---|---|---|
| LMArena Non-English | 1452 | 1441 |
| LMArena Chinese | 1522 | 1481 |
| LMArena Russian | 1451 | 1458 |
| LMArena French | — | 1476 |
| LMArena German | — | 1465 |
| LMArena Japanese | — | 1449 |
| LMArena Korean | — | 1417 |
| LMArena Spanish | — | 1443 |
Instruction Following Claude Sonnet 5.5 leads
Claude Sonnet 5.5: 78.3 (#11), Grok 4.20 (Non-Reasoning): 74.8 (#83)
| Benchmark | Claude Sonnet 5.5 | Grok 4.20 (Non-Reasoning) |
|---|---|---|
| LMArena Instruction Following | 1495 | 1420 |
Long Context Too close to call
Claude Sonnet 5.5: 45.9 (#28), Grok 4.20 (Non-Reasoning): 45.5 (#34)
| Benchmark | Claude Sonnet 5.5 | Grok 4.20 (Non-Reasoning) |
|---|---|---|
| LMArena Longer Query | 1498 | 1437 |
| CL-bench | — | 22.2% |
| CL-bench Life | — | 11.9% |
Writing & Preference Too close to call
Claude Sonnet 5.5: 66.0 (#40), Grok 4.20 (Non-Reasoning): 65.7 (#44)
| Benchmark | Claude Sonnet 5.5 | Grok 4.20 (Non-Reasoning) |
|---|---|---|
| LMArena Text | 1471 | 1451 |
| LMArena Creative Writing | 1465 | 1438 |
| LMArena Multi-Turn | 1474 | 1456 |
| EQ-Bench Creative Writing | — | 1574 |
Frequently asked questions
Is Claude Sonnet 5.5 better than Grok 4.20 (Non-Reasoning)?
Claude Sonnet 5.5 is the stronger model overall, scoring 61.9 to 48.6 on the Noometry Index. Grok 4.20 (Non-Reasoning) costs 2.6× 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 Grok 4.20 (Non-Reasoning)?
Grok 4.20 (Non-Reasoning) is cheaper. It lists at $1.25 per million input tokens and $2.50 per million output tokens; Claude Sonnet 5.5 lists at $2 and $10.
Is Claude Sonnet 5.5 or Grok 4.20 (Non-Reasoning) better for coding?
Claude Sonnet 5.5 scores higher on coding benchmarks: 67.3 versus 42.1 in the Noometry coding category.
Which has the bigger context window?
Both accept 1M tokens.
How many benchmarks do Claude Sonnet 5.5 and Grok 4.20 (Non-Reasoning) share?
23 benchmarks have published results for both models. Claude Sonnet 5.5 has 32 scored results on Noometry and Grok 4.20 (Non-Reasoning) has 46.