RAG chunk calculator

Client

Given a total length, chunk size, and overlap, estimate how many sliding windows you need—useful when planning retrieval-augmented generation (RAG) pipelines. Pair with the token estimate when your limits are in tokens.

Sliding-window count

The first chunk covers the first chunk size units. Each next chunk starts chunk size − overlap units after the previous start, until the rest of the document fits in one final window. Empty length yields zero chunks.

Parameters

?

Lengths are in one unit you choose (characters or tokens)—stay consistent. This counts overlapping sliding windows: each chunk starts after the previous by chunkSize − overlap. Real pipelines may add sentence boundaries or tokenizer steps.

Stride (chunk − overlap)
448
Approx. chunk count
112

URL query: ?len=50000&chunk=512&overlap=64

Nearby workflows on Toolcore

Common use cases

  • Ballpark how many vectors or embedding API calls you need before splitting real documents.
  • Compare overlap settings when tuning stride versus redundant content between chunks.
  • Teach RAG concepts using fixed numbers before adding sentence-aware splitters.

Common mistakes to avoid

  • Forgetting tokenizer vs character chunks

    If your pipeline chunks by tokens, measure length in tokens everywhere. Mixing characters here with token chunk sizes elsewhere skews counts.

  • Assuming chunks align with sentence boundaries

    This calculator uses a pure sliding window. Production RAG often snaps to sentences or paragraphs.

FAQ

What unit should I use for length and chunk size?

Any consistent unit—characters, tokens, or abstract units—as long as document length, chunk size, and overlap use the same one.

Is document text sent to a server?

No. Only the three numbers you type are used in your browser. There is no upload field on this page.

Common search terms

Phrases people search for that match this tool. See the full long-tail keyword index.

  • rag chunk size calculator
  • embedding chunk planner

More tools

Related utilities you can open in another tab—mostly client-side.