Split PDF by File Size
Split a PDF by file size when it’s too big to send in one go: type the limit — 25 MB for Gmail, 2 MB for a job portal — and get as few parts as possible, each one under it.
Split PDF by Size
Fit meter
Settings appear once you add a PDF.
Your settings are saved on this device.
25 MB is Gmail’s limit for all attachments together; Outlook’s is 20 MB.
Ctrl + Enter runs it ·
Bytes of your files sent anywhere: 0 B · nothing leaves this tab
Every request this page makes is listed as it happens. You’ll see our own code loading, and for some formats a codec engine, but never your file going out.
- Waiting for network activity…
Check it yourself: open your browser’s developer tools on the Network tab, or turn off Wi-Fi once the page has loaded. The tools keep working.
- 100% private Your PDFs never leave this device. Everything runs in your browser.
- No limits No file-size cap, no watermark, no sign-up and no daily quota. Free.
- Batch ready Add as many PDFs as you like; each one is handled and saved in one go.
How to split a PDF by file size
-
Add your PDF: Drop the big PDF.
-
Check the settings: Type the limit — 25 MB for Gmail, 20 MB for Outlook, or whatever the portal states.
-
Save the result: Save the parts. Each holds as many whole pages as fit under the limit, so you send the fewest files.
Why it doesn’t upload
A PDF too big to email is usually a big scan — a whole application, a year of statements. Splitting it here means the full file never has to be uploaded, which is the very thing its size makes slow.
Check it in your browser’s Network tabWorth knowing
- A single page bigger than the limit can’t be split further; it goes in its own part and is flagged. Compress the PDF first to fix that.
- Parts are split at page boundaries — a page is never cut in two.
- Shared fonts and images are included in every part that needs them, so the parts add up to a little more than the original.
Under the hood
What happens to your file
To keep each part under a size limit, the tool saves candidate parts and measures them, using a galloping then binary search over page counts — so a 300-page file needs a few dozen trial saves, not three hundred. Pages are never recompressed to fit; a single page larger than the limit is reported, not squeezed.
Reference: pdf-lib documentation
Why split a PDF by file size?
Email attachments, upload portals and messaging apps all cap file size. When a PDF is over the limit and compressing it would cost too much quality, splitting it into parts that each fit is the clean answer. This tool measures real saved parts — it doesn’t estimate — and finds the fewest parts that each stay under your limit.
It runs in your browser, so a large and often sensitive document isn’t uploaded just to be cut down to size.
When to split a large PDF into smaller parts
-
Emailing a PDF over 25 MB
Gmail allows 25 MB of attachments per email; split a large file into parts that fit, one email each.
-
Splitting a PDF into 2 MB chunks for an upload portal
Job, visa and government portals often cap each file at 2 MB or 5 MB. Set the limit to 2 MB and every part is saved under it, ready to upload one by one.
-
Court and tender submissions
E-filing systems commonly set a per-file maximum and accept several files.
-
Messaging apps
Send a large manual or scanned book in pieces small enough for chat attachments.
-
Slow connections
Smaller parts are easier to upload and resend if one fails.
Tips for splitting a PDF to fit an upload limit
- Set the limit slightly under the published one — 24 MB for a 25 MB cap — to leave room for the email itself.
- A single page bigger than the limit can’t be split further; compress the PDF first to fix that.
- Parts add up to a little more than the original, because shared fonts and images go into every part that needs them.
- Pages are never cut in two: splits always fall between pages.
- Want the parts at chapter boundaries instead? Try Split by Bookmarks.
Questions
How do I split a PDF into parts under 10 MB?
Type 10 MB as the limit and press Split by size. You get the fewest possible parts, each under 10 MB.
How do I email a PDF that’s too large?
Type 25 MB (Gmail) or 20 MB (Outlook) as the limit and split it into parts that each fit, then send them in separate emails. Or make it smaller with a compressor first.
Why is one part still too big?
Because one page on its own is bigger than the limit — usually a high-resolution scan. Compress the PDF first, then split.
Does splitting by size lose quality?
No. Pages are copied exactly; the tool only decides where one part ends and the next begins.