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How to split a PDF into separate files without uploading it

2026-10-04 · 5 min read

To split a PDF into several files with AstralPDF, run the Split PDF tool once per file you want. Load the document, type the page range for the first piece (for example 1-4) and download it, then change the range box to the next piece (5-9) and download again. Each run produces one PDF containing only the pages you typed. It all happens in your browser tab, and your original file is not changed.

TL;DR: one run, one output file. Three chapters means three runs. Every download is named split- followed by the original file name, so rename each one as it arrives. The range box clamps pages that are too high, sorts what you type, and reads an open-ended range like 5- as 1-5, so always type the last page.

Why does the tool make only one file at a time?

Because the page range box is the only control. It takes the pages you list, copies them into a new document and downloads that single document. There is no option to cut every page, or every ten pages, into separate files in one go. For a handful of pieces that is fine. For a document you want in fifty pieces, it is tedious, and a desktop tool that splits by interval will serve you better.

How do I cut one document into several files?

• Decide the pieces first and write them down as page ranges. A 12 page file in three parts is 1-4, 5-9 and 10-12. Ranges that do not overlap give you pieces that add back up to the whole.
• Open Split PDF and load the file. The tool reads the page count and fills the range box with the whole document, for example 1-12.
• Replace the box with the first range, then split and download. The file arrives named split- plus the original name.
• Rename it straight away, for example to part-1.pdf. The next download has the same name, and your browser will either add a number to it or ask you what to do.
• Type the second range in the same box and download again. Repeat until every piece is out, renaming each one.

Open the Split PDF tool: load the file, type one range per run and download each piece.

What does the range box accept?

Single pages and ranges separated by commas, such as 1-3, 7, 10-12. Spaces around the commas do not matter. The tool shows the total number of pages next to the box, so you can check your last number against it. A few behaviours are worth knowing before you rely on them, because the tool does not warn you about any of them.

The open-ended case is the one that bites. Typing 5- looks like 'from page 5 on', but the missing end is read as zero and pulled up to page 1, so you silently get the front of the document. Type the real last page instead, which the tool shows you.

What should I check in each piece?

• The page count. Open each file and compare it with the range you typed. A 5-9 piece should have 5 pages.
• The first and last page. They are the ones an off-by-one error shows up on.
• That the pieces together cover everything. Add the page counts up and compare with the original.
• File sizes. Fonts and images travel with each piece, so a piece can be larger than its share of the original. That is expected, and the split guide explains why.

What if the PDF has a password?

A file that asks for a password when you open it cannot be loaded by the tool, and you will see the invalid PDF message. Unlock it first with the password you already know, then split the unlocked copy. If a piece should be protected again before it goes to its recipient, add the password to that piece afterwards.

See also: how to split a PDF, and what it loses: what does not survive a split, such as page labels and bookmarks.

See also: how to delete pages from a PDF: to take pages out rather than split into parts, list the ones that stay.

• pdf-lib documentation: PDFDocument, including copyPages, the call that copies pages between documents

Frequently asked questions