Claude Sonnet 5.5 scores 68.5 on the Respan Index (#6), ahead of GPT-5.6 Terra at 53.5 (#14). Claude Sonnet 5.5 leads on 20 of the 21 benchmarks both report. Claude Sonnet 5.5 is 1.1x cheaper per token at list price. GPT-5.6 Terra has the larger context window (1.1M tokens).
* Estimated: no published scores in that category. How the Respan Index works
| GPQA Diamond | 95.6% | 92.9% |
| LiveBench Agentic Coding (LiveBench) | 56.3% | 54.9% |
| LiveBench Coding (LiveBench) | 91.4% | 78.2% |
| LiveBench Data Analysis (LiveBench) | 78.6% | 79.3% |
| LiveBench Instruction Following (LiveBench) | 70.5% | 64.6% |
| LiveBench Language (LiveBench) | 83.4% | 82.9% |
| LiveBench Mathematics (LiveBench) | 96.7% | 94.9% |
| LiveBench Reasoning (LiveBench) | 91.6% | 90.6% |
| Mystery Game Puzzles (Epoch AI) | 65% | 35% |
| OTIS Mock AIME 2024-2025 (Epoch AI) | 100% | 99.7% |
| SAGE (Vals AI) | 51.8% | 47% |
| SimpleQA Verified | 46.5% | 43.2% |
| Terminal-Bench 4.0 (Vals AI) | 64.1% | 22.7% |
| LMArena Agent (LMArena) | 0.1252 | 0.004 |
| LMArena Elo | 1471 | 1466 |
| LMArena Vision (LMArena) | 1268 | 1268 |
| SimpleBench (SimpleBench) | 75.9% | 48.9% |
Higher is better. Each score links to where it was published.