Split PDF by Size

Overview

Break a big PDF into email-friendly pieces

Split PDF by Size breaks a large PDF into smaller files that each stay under a file size you choose — for example under 25MB so they'll send by email. Set a target in MB, preview the chunks, and download them individually or as a ZIP. Nothing is uploaded.

Load a PDF and the tool shows its size, page count, and an estimate of how many chunks you'll get. Drag the Target Chunk Size slider to your limit — anywhere from 1MB to 100MB (set it just under 25MB for email) — and a table recalculates the chunks as you move it, listing each one's page range and estimated size. After you split, the table shows the measured size of every part.

A Smart Splitting option (on by default) keeps things tidy: it evens out the parts so you don't end up with a lone single page as the last chunk, and every part still stays under your target. Turn it off to fill each part as full as it will go. When you're happy with the preview, click Split PDF Document and download each chunk, or grab them all in one ZIP.

Everything runs locally, so even a large, confidential file is never uploaded to a server. The pages are copied as-is into the chunks, so there's no quality loss, no watermark, and no signup. The input limit is 100MB.

Two honest notes. The preview sizes are estimates; the split itself measures every part and keeps it under your target, unless a single page is bigger than the target on its own, which the tool marks. And this splits by size; if you'd rather choose exact pages or get one file per page, use Split PDF. To make the whole document smaller first, try Compress PDF.

Use Cases

When splitting by size helps

Email a big PDF. Break it into sub-25MB parts that actually send.
Beat upload limits. Get each piece under a portal's cap.
Faster transfers. Move smaller chunks over slow connections.
Archiving. Store a huge document as manageable segments.
Private files. Split without uploading the document.

Guide

How to split a PDF by size

Step 1: Upload your PDF

Drag it into the drop zone or click to browse (up to 100MB). The panel shows size, pages, and estimated chunks.

Step 2: Set the target size

Drag the Target Chunk Size slider to your limit in MB — for email, set it a little under 25MB. The chunk table updates live.

Step 3: Choose Smart Splitting

Leave it on to even out the parts and avoid an orphan trailing page, or turn it off to fill each part as full as it will go.

Step 4: Split and download

Click Split PDF Document, then download each chunk or Get ZIP for all of them.

Realistic example. A 60MB report won't email. Set the slider to about 20MB, keep Smart Splitting on, and split — you get three or four chunks, each under the limit, that send without bouncing.

Advanced tip. Some services count an attachment as larger than the file itself (email encoding adds about a third), so for a 25MB email cap set the target nearer 18MB.

Common mistake to avoid. If you need specific pages together rather than size-based cuts, use Split PDF instead — this tool optimizes for file size, not page selection.

Recommendation. Want one smaller file instead of several? Compress PDF may get the whole document under the limit.

Support

Frequently Asked Questions

How do I split a PDF by file size?

Upload the PDF, drag the Target Chunk Size slider to your limit in MB, and the tool previews the chunks in a table. Click Split PDF Document, then download each part or grab them all as a ZIP. Each chunk is built to stay under the size you set, and it all runs in your browser.

How do I split a PDF so I can email it?

Set the Target Chunk Size a little under your provider's limit — around 20MB works for the common 25MB cap on Gmail and Outlook. Split the file, and each chunk will be small enough to attach. Send them across a few emails, or share the ZIP via a link.

Are the chunk sizes exact?

The table before you split is an estimate, worked out from what each page actually holds, so a photo page counts for more than a text page. When you split, every part is measured, and a part that comes out over your target hands its last page to the next part. The one exception is a single page that is bigger than the target by itself: it becomes its own part and the tool marks it.

What is Smart Splitting?

Smart Splitting (on by default) evens out the parts so you don't end up with an awkward single page as the last one. You get the same number of parts, each still under your target. Turn it off to fill each part as close to the target as it will go, in page order.

Will splitting reduce the quality of my PDF?

No. The pages are copied into the chunks exactly as they are — no re-compression or rasterizing — so text stays selectable and images keep their resolution. Splitting only divides the document; it doesn't change how the pages look.

How do I download all the chunks at once?

After splitting, click Get ZIP to download every chunk in a single archive, or use the individual download links to grab specific parts. The ZIP keeps the chunks in order, so reassembling or sending them is straightforward.

Is there a maximum file size I can upload?

The tool accepts PDFs up to 100MB. Because everything is processed in your browser, very large files also depend on your device's memory — a big document splits faster on a laptop than on an older phone.

Are my files uploaded — is it safe?

No. The splitting happens entirely in your browser, so the PDF never leaves your device or reaches a server. That's important for large, sensitive documents. Closing the tab clears the file from memory.

Can I split a PDF by size on my phone?

Yes. The tool works in any modern browser on iPhone or Android — no app needed. Upload, set the target size, and download the chunks. Large files use more memory, so they're smoother on a laptop than on an older phone.

Is it free, with no watermark or signup?

Yes. Splitting is free, the chunks have no watermark, and there's no account to create. Set your size limit and download the parts — no paywall before the download.

Should I split by size or by page?

Split by size when your goal is a file-size limit, like email or an upload cap — this tool does that. Split by page when you want specific pages or one file per page, which is the Split PDF tool. Pick based on whether MB or page selection matters.

Can I split an encrypted (password-protected) PDF?

Not while it's locked. The tool needs to read the document's structure to size and split it, which encryption blocks. Remove the password first with Unlock PDF, then split the unprotected copy.

Can I send the result to another tool without downloading it?

Yes. Once the tool has finished, a Send to button sits beside Download. Pick another tool and it opens with the result already loaded: no second download, no re-upload. Suggested next steps for this PDF: Merge PDF, Compress PDF and PDF to JPG. The handover stays on your device, held in this browser for a few seconds while the next tool opens, then deleted.

Still have questions?

If you can't find the answer you're looking for, feel free to contact our support team.

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Estimated parts