Tokens & Pricing
Input tokens (prompt tokens)
The tokens you send into the model — your prompt, the instructions, any documents or history you include. You pay for these whether or not the answer is any good.
Example
You paste a 4,000-word support-ticket thread and ask the model to summarize it. Those 4,000 words are roughly 5,300 input tokens — billed before the model writes a single word of the summary.
Related terms
Token
The unit AI models read and write, and the unit you're billed in. A token is a chunk of text — often a word, a piece of a word, or a punctuation mark. Models don't see letters or words; they see tokens.
Output tokens (completion tokens)
The tokens the model generates back to you. Output tokens almost always cost more per token than input tokens — often 3–5× more — because generating text is the expensive part.
Cached tokens
Input tokens the provider recognizes from a previous request and serves at a steep discount instead of full price. Distinct from a full cache hit — here the model still runs, it just doesn't re-charge full rate for the repeated part of your prompt.
Prompt compression
Shrinking a prompt to fewer tokens without losing what the model needs — trimming boilerplate, deduplicating context, summarizing history — so you pay for less input.