Splitting a PDF by file size is one of the most practical but technically tricky operations. Unlike splitting by page count (simple math) or bookmarks (tree traversal), size-based splitting requires estimating and controlling the output size of each chunk — and PDFs don't have a simple "size per page" property.
Here's how to build a browser-based PDF splitter that respects file size constraints.
The challenge
PDFs are notoriously unpredictable in terms of size. Two PDFs with the same number of pages can differ by 10x in file size depending on:
Image resolution and compression
