Compare / Claude Opus 5.5 vs grok-4.20-0309-reasoning
Claude Opus 5.5 vs grok-4.20-0309-reasoning
7 results from 3 sources that measured both models. Each row is in the source's own units; there is no overall winner.
| Benchmark | Metric | Claude Opus 5.5 | grok-4.20-0309-reasoning |
|---|---|---|---|
| Artificial Analysisreported | Artificial Analysis Intelligence Indexindex score | 57.6 | 25.2 |
| Artificial Analysisreported | Humanity's Last Exam% of questions | 61.4% | 32.4% |
| Artificial Analysisreported | Long-context reasoning (AA-LCR)% of questions | 84.7% | 67.7% |
| SimpleQA Verified (Epoch AI)reported | Correct answers% of questions | 72.2% | 30.2% |
| UGI Leaderboardreported | Requested-length error% off the requested word count | 2.0% | 46.0% |
| UGI Leaderboardreported | Style adherencescore from 0 to 1 | 0.43 | 0.33 |
| UGI Leaderboardreported | Writing scorescore out of 100 | 70.0 | 55.3 |
Bold green marks the better value on that metric. Where a source reports ranges that overlap, the difference may not be meaningful; see the benchmark page for ranges.