Model

gpt-oss-120b

Family
GPT open-weight
Context window
Open weights
Yes
Release date
2025-08-05

Benchmark notes

OpenAI's first open-weight model release since GPT-2. 117 billion parameters using a mixture-of-experts architecture with approximately 5.1 billion active parameters per forward pass. Described as the most powerful open model runnable on a single H100 GPU (Graphics Processing Unit). Supports fine-tuning. Represents OpenAI's first significant open-weight release in the modern era.