How to calculate RAG chunk count and overlap

Vector search pipelines split documents into overlapping chunks before embedding. The RAG Chunk Calculator estimates chunk count from token volume, chunk size, and overlap percentage.

How it works

1. Total tokens — corpus or document token count.
2. Chunk size — tokens per chunk (e.g. 512 or 1024).
3. Overlap — shared tokens between adjacent chunks.

Why overlap matters

Overlap preserves context across chunk boundaries — a sentence split mid-thought still appears whole in at least one chunk. More overlap means more chunks and higher embedding cost.

Token budgeting

Estimate embedding cost with the Embedding Cost Calculator or count tokens with the AI Token Calculator.

The How to calculate RAG chunk count and overlap is free, runs locally, and never sends your data to a server. More developer tools at maratool.com.