Vector Stores search pricing in the API

API
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Hi all,

Just wondering if anyone could help clear up the Vector Stores pricing for me - in the docs, it is stated that:

You first GB is free and beyond that, usage is billed at $0.10/GB/day of vector storage. There are no other costs associated with vector store operations.

However, in the API usage section I’m being billed for several “file search tool calls”, despite manually using vector store search rather than Responses File Search or Assistants File Search.

I haven’t been able to find any pricing docs for Vector Stores other than $0.10/GB/day for storage, but I noticed that API keys used for vector search must have write permissions for Assistants, suggesting that vector search may internally use the Assistants File Search tool. But even if this is the case, the Pricing docs suggest that “File Search Tool Calls” are only billable when used through Responses (“Does not apply on Assistants API”), so I still don’t feel that I ought to be charged per search, at least according to the docs.

Thanks in advance if anyone is able to figure this out

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  • Tool use: Free in Assistants; Nov 2023
  • Tool use: Now billed per call in Responses endpoint, introduced March 11 2025
  • Direct API search API: introduced March 11 2025 …

It is pretty easy to infer that the per-call use of the search API will also be billed the Responses rate. Semantic search requires sending that input to an embeddings AI model, just as was done for all the document chunks. There’s not even any input tokens to a language model tool to offset OpenAI’s small cost when you receive search directly.

The price model is optimized for if you have max 500MB to search across, and you have a low volume of searches. Otherwise, your own vector database becomes more attractive.