Split large PDF files by size for free. Divide PDFs into smaller parts for email and uploads. Browser-based processing. Free, private, in-browser.
File size restrictions exist throughout digital communication. Email providers cap attachments. Upload portals enforce limits. Messaging apps restrict file sizes. When your PDF exceeds these thresholds, you need a reliable method to divide it into smaller, transmittable parts. This splitter creates multiple PDFs that each stay within your specified size limit.
Unlike page-based splitting that divides at specific page numbers, size-based splitting focuses on file size. You specify a maximum megabyte limit—say 5MB for email attachments. The tool processes pages sequentially, adding each to the current split file. When adding another page would exceed your limit, it starts a new file.
This approach accommodates documents with varying page sizes. A report might have text-heavy pages that compress well alongside image-heavy pages that don't. Size-based splitting naturally handles these variations, ensuring every resulting file meets your size constraint.
Email remains the predominant method for document sharing in business contexts. When a comprehensive report exceeds Gmail's 25MB limit, you face a choice: use cloud storage links or split the document. Many recipients prefer direct attachments for security reasons or offline access. Splitting enables direct email delivery.
Government portals frequently impose strict upload limits. Visa applications, permit submissions, and regulatory filings often cap files at 10MB or less. A detailed application package with supporting documentation may need division to meet these requirements.
Insurance claims documentation can become substantial. Policy documents, damage photos, repair estimates, and correspondence accumulate into files that exceed submission limits. Splitting allows complete documentation while respecting portal constraints.
Academic submissions through course management systems face similar restrictions. Research papers with extensive appendices, image galleries, or data tables may need division for successful upload.
The splitting algorithm reads your PDF using the pdf-lib library. It extracts pages one by one, measuring the size each would add to the current split. When the cumulative size approaches your limit, it finalizes that split and begins another. The process continues until all pages are distributed.
Processing occurs entirely within your browser. The PDF loads into memory as an ArrayBuffer, processes through JavaScript, and generates multiple blobs for download. No file data transmits to external servers at any point.
Set your limit below the actual restriction to account for overhead. Email encoding can add 33% to file size. MIME boundaries add additional bytes. A 7MB split might become 9.3MB after email encoding.
Number your emails when sending split files. "Part 1 of 4" in subject lines helps recipients track completeness and reassemble correctly.
Keep the original file. Split parts can reunite using our Merge PDF tool, but having the original simplifies future needs.
Documents requiring splitting often contain substantial information—comprehensive reports, detailed proposals, extensive records. This information may be confidential. Our tool processes everything locally. Your PDF never uploads to any server. We cannot view, access, or store your content. This makes the tool appropriate for sensitive business documents, financial records, and confidential materials.
Professionals emailing large reports to clients. Applicants submitting comprehensive packages to portals with size restrictions. Insurance adjusters documenting extensive claims. Researchers sharing data-heavy publications. Anyone who has encountered "file exceeds maximum size" and needed a practical solution.
Alternative approaches include compressing the PDF if the size reduction is sufficient for your needs. For viewing document details before processing, our PDF Metadata Viewer reveals file properties and page counts.
If a file is only slightly over a limit — say 12MB against a 10MB cap — compression alone is often enough and keeps the document in one piece, which recipients prefer. If the file is several times larger than the limit, compress first and then split: compression reduces the number of parts you have to send, and fewer parts mean fewer chances for a recipient to miss one. Our Compress vs Split comparison walks through this decision with examples.
Limits change, so always confirm with the service you are using, but these are common starting points: many email providers allow roughly 20–25MB per message including encoding overhead; job portals and applicant tracking systems frequently cap uploads between 2MB and 5MB; government and visa portals often allow 1–10MB per document; learning management systems vary widely by institution. Choosing a target 15–20% below the published limit avoids last-minute rejections. See our guide on PDF size limits for email and job applications for practical advice.
Pages differ in weight. A page of plain text may be a few kilobytes, while a page containing a full-resolution photograph can be several megabytes. Because the tool never cuts a page in half, parts end where the next page would push the total over your limit. Shared resources such as embedded fonts are also copied into each part so every file opens on its own, which adds a little overhead per part. That is why five parts from a 45MB file will rarely be exactly 9MB each.
Tell the recipient how many parts to expect in your first message, label each email "Part X of Y", and keep the numbered file names unchanged so the order is obvious. If the recipient needs a single document again, they can recombine the parts with Merge PDF in the correct sequence. For very large or confidential material, our guide to sharing large files safely covers alternatives to email.
Imagine a small construction firm preparing a tender. The package contains a 12-page cover letter and method statement, 40 pages of scanned certificates, a 6-page price schedule and 20 pages of site photographs. The combined PDF is 38MB, and the client's procurement portal accepts a maximum of 10MB per upload. Setting the limit to exactly 10MB is risky, because some portals count the file slightly differently from your operating system. A target of 8.5MB leaves a comfortable margin.
With that target, the text-heavy opening pages barely register, so the first part holds the letter, the method statement and most of the certificates. The photograph section is much heavier, so it spreads across three further parts. The result is five files, each opening independently, each under the portal limit, and each numbered so the evaluator can read them in order. Had the firm compressed the photographs first, the same package might have fitted into two or three parts — which is why checking the heaviest section before splitting is worth a minute of your time.
Start from the smallest limit anywhere in the delivery chain, not the largest. If you are emailing a colleague who will forward the files to a portal with a 5MB cap, the portal is the real constraint. Then subtract a safety margin:
A note on units: some systems treat 1MB as 1,000,000 bytes and others as 1,048,576 bytes. The difference is under 5%, which is another reason a margin protects you.
Each output file is a complete, standalone PDF. Page content — text, vector graphics, images and form appearance — is copied exactly as it exists in the source, without re-rendering, so the split itself does not reduce visual quality. Page size and orientation are preserved per page, which matters for mixed documents such as an A4 report with A3 fold-out drawings. Fonts and images that a page depends on are carried into whichever part contains that page, so a reader can open part three without ever seeing part one.
Some document-level features are not carried over in the same way. A table of contents that links across the whole original, document-wide bookmarks, and links that jump from one page to another in a different part cannot work once those pages live in separate files. Digital signatures applied to the original are also invalidated by any change to the file, including a split, because the signature covers the exact bytes of the signed document. If a signature matters, ask the sender for signed parts or share the signed original through a method that accepts its full size.
Both tools divide a document, but they answer different questions. Splitting by size answers "how do I get this under the limit?" and lets the page boundaries fall wherever the weight dictates. Splitting by range answers "how do I separate chapter two from chapter three?" and gives you control of the boundaries, whatever the resulting sizes. When the content has a natural structure that recipients rely on — separate invoices, separate student submissions, separate contract schedules — use Split PDF by Range so each file is meaningful on its own. When the content is one continuous document and the only problem is delivery, split by size.
You can also combine them. Split a large document into its logical sections by range first, then run only the oversized sections through the size splitter. This keeps the structure clear for the reader while guaranteeing every file meets the limit.
Because processing happens on your device, speed depends on your device's memory and processor. A modern laptop handles a 100MB PDF comfortably. A phone with limited memory may slow down or reload the page with very large files, particularly if many other tabs are open. If that happens, close other tabs, keep the screen awake during processing, and consider compressing the file first so there is less data to hold in memory. Nothing is lost if the tab reloads — your original file is untouched on your device, and you can simply start again.
If the original PDF was created with tags for screen readers, those tags describe the reading order of the whole document. After splitting, readers using assistive technology will still be able to read the text on each page, but the overall structure may be less clear than in a single file. To help, name the parts descriptively — for example Annual-Report-2026-part2-of-4-financials.pdf rather than just a number — and mention in your message which pages each part contains. This small habit helps every recipient, not only those using screen readers.
Does splitting reduce quality? No. Pages are copied, not re-compressed. If you need smaller files with lower quality, that is a compression step, not a split.
Can the recipient put the parts back together? Yes. Any PDF merging tool, including our Merge PDF page, can rejoin them in order.
Is there a page or file limit? The practical limit is your device's available memory rather than a fixed number. Very large files work best on a desktop browser.
Why did I get more parts than I expected? Usually because a few heavy image pages sit next to each other, or because shared fonts and images are repeated in each part so every file can open alone.
A final-year project report with screenshots, charts, and scanned approval sheets can reach 40–80 MB. Supervisors frequently ask for it by email, and most mail services reject attachments above 20–25 MB. Rather than uploading to a cloud drive and sharing a link that a university mail filter may block, split the report into parts of about 18 MB. Leaving a margin below the stated limit matters, because email encoding adds roughly a third to the size of an attachment during transmission. A 24 MB file that looks acceptable on your computer can arrive as more than 30 MB and bounce.
Name the resulting files clearly, such as Report-part1-of-3.pdf, and mention in the email body how many parts to expect. The recipient can read each part independently or rejoin them with Merge PDF. If the supervisor needs one file, ask whether a compressed version is acceptable and try PDF Compress before splitting.
Messaging apps and government or court e-filing systems often apply their own caps, and some portals reject any single file above 2 MB or 5 MB. Choose a target slightly below the published number, for example 1.8 MB for a 2 MB rule. When a portal also limits the number of attachments, compare the number of parts the tool produces with the slots available. If there are too many parts, compress first to reduce the total, then split; if a single scanned page alone exceeds the limit, compressing that page is the only route, since splitting cannot divide one page.
The splitter works in your browser with the pdf-lib library. It adds pages one at a time to a new document and measures the saved size after each addition. When the next page would push the part above your target, the current part is closed and a new one begins. Because each part must be a complete, standalone PDF, shared resources such as fonts are written into every part that uses them. That is why the sum of all parts is usually a little larger than the original file, and why measured sizes, not page counts, decide where each split happens. Pages are never re-encoded, so the content of each page is identical to the source.
Email services and upload portals enforce size limits. Gmail allows 25MB attachments, many job sites cap at 5MB. Splitting ensures each part stays within these limits.
No. Pages remain exactly as they appear in the original. The tool simply distributes pages across multiple files without any modification to content or formatting.
The tool adds pages to a split file until approaching the target size, then starts a new file. Some pages may be larger than others, so exact sizes vary, but each file stays at or below your specified limit.
This tool splits automatically based on size. Each page stays with its neighbors up to the size threshold. For manual page selection, a page-based splitter would be needed.
No. Files are processed locally in your browser whenever possible and are not stored on our servers. The splitting runs entirely via JavaScript.
Pages cannot be subdivided. If one page exceeds your target size (rare with text, possible with large images), that page forms its own split file that may exceed the limit.
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