Model comparison
Claude Opus 5.5 vs Grok 4.20 (Non-Reasoning)
Claude Opus 5.5 is the stronger model overall, scoring 68.5 to 48.5 on the Noometry Index. Grok 4.20 (Non-Reasoning) costs 5.1× less per token, which makes it the better buy when Claude Opus 5.5's lead doesn't matter for your workload.
Last verified . 24 shared benchmarks.
Summary
- They share 24 benchmarks with published results for both. Claude Opus 5.5 scores higher in 10 categories and Grok 4.20 (Non-Reasoning) in 0 categories; 10 gaps are clear of the uncertainty.
- The widest gap is in math, where Claude Opus 5.5 leads 92.4 to 48.0.
- The biggest single-benchmark swing is ProofBench: 100% for Claude Opus 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 $4 / $20 for Claude Opus 5.5.
Side by side
| Claude Opus 5.5 | Grok 4.20 (Non-Reasoning) | |
|---|---|---|
| Provider | Anthropic | xAI |
| Noometry Index | 68.5 | 48.5 |
| Released | 2026-09-22 | 2026-02-17 |
| Weights | Proprietary | Proprietary |
| Context window | 1M | 1M |
| Max output | 128K | 30K |
| Input $ / M tokens | $4 | $1.25 |
| Output $ / M tokens | $20 | $2.50 |
| Results tracked | 35 | 46 |
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Category by category
Coding Claude Opus 5.5 leads
Claude Opus 5.5: 71.4 (#1), Grok 4.20 (Non-Reasoning): 41.8 (#104)
| Benchmark | Claude Opus 5.5 | Grok 4.20 (Non-Reasoning) |
|---|---|---|
| LMArena WebDev | 1820 | 1374 |
| LMArena Coding | 1545 | 1458 |
| FrontierCode | 54.4% | — |
| CursorBench | 57.8% | — |
| FrontierSWE | 62.3% | — |
| SciCode | 66.9% | — |
| WeirdML | — | 52.3% |
| MirrorCode | 77.4% | — |
| ALE-Bench | — | 1,150 |
Agentic & Tool Use Claude Opus 5.5 leads
Claude Opus 5.5: 45.3 (#13), Grok 4.20 (Non-Reasoning): 34.3 (#43)
| Benchmark | Claude Opus 5.5 | Grok 4.20 (Non-Reasoning) |
|---|---|---|
| Terminal-Bench | — | 57.3% |
| APEX-Agents | 73.5% | — |
| τ²-bench Banking | — | 18% |
| GDP.pdf | 30.6% | — |
| LMArena Search | — | 1189 |
| Vending-Bench 2 | — | 4,663 |
Reasoning Claude Opus 5.5 leads
Claude Opus 5.5: 79.5 (#2), Grok 4.20 (Non-Reasoning): 52.2 (#30)
| Benchmark | Claude Opus 5.5 | Grok 4.20 (Non-Reasoning) |
|---|---|---|
| ARC-AGI-2 | 92.5% | 65.1% |
| NYT Connections (extended) | 88.5% | 85.4% |
| ARC-AGI-1 | 97.5% | 89.5% |
| LMArena Hard Prompts | 1545 | 1451 |
| DTBench | 98.9% | 90.1% |
| LMCA | 68.2% | 38.7% |
| Kagi LLM Benchmark | — | 75% |
| CritPt | 31.7% | — |
| Chess Puzzles | — | 24% |
| Thematic Generalization | — | 63.8% |
| EBR-Bench | 71.4% | — |
| Mystery Game Puzzles | 71% | — |
| Epoch Capabilities Index | — | 152.01 |
| ForecastBench | — | 61.4 |
Math Claude Opus 5.5 leads
Claude Opus 5.5: 92.4 (#2), Grok 4.20 (Non-Reasoning): 48.0 (#54)
| Benchmark | Claude Opus 5.5 | Grok 4.20 (Non-Reasoning) |
|---|---|---|
| FrontierMath (Tiers 1-3) | 91.2% | 44.9% |
| FrontierMath Tier 4 | 95% | 17.1% |
| OTIS Mock AIME 2024-2025 | 100% | 92.2% |
| ProofBench | 100% | 14% |
| LMArena Math | — | 1455 |
Knowledge Claude Opus 5.5 leads
Claude Opus 5.5: 66.6 (#9), Grok 4.20 (Non-Reasoning): 52.8 (#54)
| Benchmark | Claude Opus 5.5 | Grok 4.20 (Non-Reasoning) |
|---|---|---|
| GPQA Diamond | 90.6% | 89.3% |
| SimpleQA Verified | 72.2% | 30.2% |
| LMArena Expert | 1564 | 1440 |
Multimodal Claude Opus 5.5 leads
Claude Opus 5.5: 56.5 (#2), Grok 4.20 (Non-Reasoning): 33.2 (#88)
| Benchmark | Claude Opus 5.5 | Grok 4.20 (Non-Reasoning) |
|---|---|---|
| LMArena Vision | — | 1263 |
| Blueprint-Bench 2 | — | 0% |
| Furniture Assembly | 83.3% | — |
| LMArena Document | — | 1416 |
Multilingual Claude Opus 5.5 leads
Claude Opus 5.5: 59.8 (#1), Grok 4.20 (Non-Reasoning): 54.7 (#38)
| Benchmark | Claude Opus 5.5 | Grok 4.20 (Non-Reasoning) |
|---|---|---|
| LMArena Non-English | 1513 | 1440 |
| LMArena Chinese | 1572 | 1481 |
| LMArena Russian | 1532 | 1457 |
| LMArena French | — | 1477 |
| LMArena German | — | 1463 |
| LMArena Japanese | — | 1450 |
| LMArena Korean | — | 1417 |
| LMArena Spanish | — | 1442 |
Instruction Following Claude Opus 5.5 leads
Claude Opus 5.5: 80.1 (#2), Grok 4.20 (Non-Reasoning): 75.0 (#79)
| Benchmark | Claude Opus 5.5 | Grok 4.20 (Non-Reasoning) |
|---|---|---|
| LMArena Instruction Following | 1535 | 1420 |
Long Context Claude Opus 5.5 leads
Claude Opus 5.5: 47.3 (#18), Grok 4.20 (Non-Reasoning): 45.4 (#33)
| Benchmark | Claude Opus 5.5 | Grok 4.20 (Non-Reasoning) |
|---|---|---|
| LMArena Longer Query | 1540 | 1436 |
| CL-bench | — | 22.2% |
| CL-bench Life | — | 11.9% |
Writing & Preference Claude Opus 5.5 leads
Claude Opus 5.5: 78.7 (#3), Grok 4.20 (Non-Reasoning): 65.9 (#42)
| Benchmark | Claude Opus 5.5 | Grok 4.20 (Non-Reasoning) |
|---|---|---|
| LMArena Text | 1518 | 1451 |
| LMArena Creative Writing | 1538 | 1439 |
| EQ-Bench Creative Writing | 2050 | 1574 |
| LMArena Multi-Turn | 1520 | 1456 |
Frequently asked questions
Is Claude Opus 5.5 better than Grok 4.20 (Non-Reasoning)?
Claude Opus 5.5 is the stronger model overall, scoring 68.5 to 48.5 on the Noometry Index. Grok 4.20 (Non-Reasoning) costs 5.1× less per token, which makes it the better buy when Claude Opus 5.5's lead doesn't matter for your workload.
Which is cheaper, Claude Opus 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 Opus 5.5 lists at $4 and $20.
Is Claude Opus 5.5 or Grok 4.20 (Non-Reasoning) better for coding?
Claude Opus 5.5 scores higher on coding benchmarks: 71.4 versus 41.8 in the Noometry coding category.
Which has the bigger context window?
Both accept 1M tokens.
How many benchmarks do Claude Opus 5.5 and Grok 4.20 (Non-Reasoning) share?
24 benchmarks have published results for both models. Claude Opus 5.5 has 35 scored results on Noometry and Grok 4.20 (Non-Reasoning) has 46.