OpenAI open-weight models
GPT-OSS Token Counter
Explore base-text tokenization for GPT-OSS 20B and GPT-OSS 120B. Harmony chat-wrapper tokens are not included.
Accuracy note
Compatible base-text encoding. Harmony formatting and inference-provider wrappers are excluded.
Frequently asked questions
Which GPT-OSS sizes are covered?
The model picker includes GPT-OSS 20B and GPT-OSS 120B.
Does this include the Harmony wrapper?
No. This page explicitly reports base-text encoding and excludes Harmony message formatting.