OpenAIclosed weightsReasoning
GPT-5.5 Pro
Parallel test-time compute tier.
Apr 23, 2026
$30 / $180
$68
1M
Benchmark scores
| Benchmark | Score | Δ vs prior | Rank (current) | Configuration | Source |
|---|---|---|---|---|---|
Humanity's Last Exam | 43.1% | #9 of 15 | no tools · lab-reported | vellum.ai ↗ | |
ARC-AGI-2 | 84.2% | #6 of 10 | leaderboard | benchlm.ai ↗ |