How much does ChatGPT API cost and how are tokens counted?

The OpenAI API is billed per token, with separate prices for input and output, and it is not included in a ChatGPT subscription. Input is everything you send (system instructions, conversation history, documents); output is the text the model returns. Prices are quoted per million tokens.

List prices in USD per 1 million tokens (input / output) as shown in the OpenRouter catalogue on 30 October 2026:

• GPT-6 Luna: 0.10 / 0.50
• GPT-6.1 Terra: 1 / 5
• GPT-6 Sol and GPT-6.1 Sol: 2 / 10
• GPT-6 Astra: 10 / 50

Batch variants on OpenRouter cost half. Example: a request with 2,000 input tokens and 500 output tokens on GPT-6.1 Sol costs 2,000 x 2 / 1,000,000 + 500 x 10 / 1,000,000 = 0.009 USD.

A token is a fragment of text, often part of a word, so the count depends on the language and the formatting. In a typical chat integration the earlier conversation is sent with every request, so long chats cost more per message. OpenAI's own price list may differ from the catalogue, so check it before you set a budget.