GPT-5.6 Sol scores 60.6 on the Respan Index (#10), ahead of Step 5 Preview at 54.9 (#12). GPT-5.6 Sol leads on 4 of the 4 benchmarks both report. Step 5 Preview is 5.6x cheaper per token at list price. GPT-5.6 Sol has the larger context window (1.1M tokens).
| Benchmark | GPT-5.6 Sol | Step 5 Preview |
|---|---|---|
| Terminal-Bench 4.0 (Vals AI) | 37.9% | 31.8% |
| LMArena Agent (LMArena) | 0.0645 | 0.0048 |
| LMArena Elo | 1484 | 1454 |
| LMArena Vision (LMArena) | 1285 | 1260 |
Higher is better. Each score links to where it was published.
* Estimated: no published scores in that category. How the Respan Index works