Claude Opus 5.5 scores 72.4 on the Respan Index (#1), ahead of GPT-5.6 Terra at 53.5 (#14). Claude Opus 5.5 leads on 19 of the 21 benchmarks both report. GPT-5.6 Terra is 1.8x 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 | 90.6% | 92.9% |
| LiveBench Agentic Coding (LiveBench) | 71.7% | 54.9% |
| LiveBench Coding (LiveBench) | 89.3% | 78.2% |
| LiveBench Data Analysis (LiveBench) | 80.3% | 79.3% |
| LiveBench Instruction Following (LiveBench) | 67% | 64.6% |
| LiveBench Language (LiveBench) | 86.3% | 82.9% |
| LiveBench Mathematics (LiveBench) | 97.1% | 94.9% |
| LiveBench Reasoning (LiveBench) | 92.2% | 90.6% |
| Mystery Game Puzzles (Epoch AI) | 71% | 35% |
| OTIS Mock AIME 2024-2025 (Epoch AI) | 100% | 99.7% |
| SAGE (Vals AI) | 45.8% | 47% |
| SimpleQA Verified | 72.2% | 43.2% |
| Terminal-Bench 4.0 (Vals AI) | 65.2% | 22.7% |
| Vending-Bench 2 (Andon Labs) | 9235.25 | 7343.21 |
| LMArena Agent (LMArena) | 0.1382 | 0.004 |
| LMArena Elo | 1504 | 1466 |
| SimpleBench (SimpleBench) | 88.4% | 48.9% |
Higher is better. Each score links to where it was published.