Mail servers and upload forms reject a file that is one byte over their limit, and guessing how many pages fit is how you end up splitting the same document three times. This measures instead of guessing: every page is saved on its own to learn what it actually costs in the output, then pages are packed into parts up to your limit, always in order and never reshuffled. A page that is larger than the limit on its own still gets its own part, because handing back one oversized part is more useful than refusing to split at all. Parts download together as a ZIP.
Features
Each page is measured by saving it, so parts land close to the limit
Type any limit — 5 MB, 800 KB, or a plain byte count
Presets for the common attachment and portal limits
Pages are packed in order, so nothing is reshuffled
Says plainly when even a single page cannot fit the limit
A preview of every part before anything is built
Download parts individually or all together as a ZIP
How to use the Split PDF by Size
Drop the PDF onto the page and let each page be measured
Type the maximum size a part may be, or pick a preset
Check the list of parts and the pages each contains
Split, then take the parts individually or as a ZIP
Parts follow page order, so the document can be reassembled by merging them.
Common errors & troubleshooting
A part came out slightly over the limit. — Shared resources such as embedded fonts are written into every part that needs them, so a part costs a little more than its pages did alone. Set the limit a few per cent below the hard one.
Every page is over the limit on its own. — The pages are too heavy to split around. Compress the document first, then split the smaller result.
Measuring a long document is slow. — Every page is saved individually to get a real size rather than an estimate. A hundred-page document takes a few seconds; that is the price of parts that actually fit.
I wanted a fixed number of pages per part. — That is a page-range split. Split PDF takes ranges directly and does not measure anything.
Frequently asked questions
Why do the parts add up to more than the original?
Each part is a complete document, so anything shared — fonts, colour profiles, an embedded logo — has to be written into every part that uses it. A ten-part split usually costs a few per cent more in total.
Can I reassemble the parts later?
Yes. The parts are in page order with nothing dropped, so merging them in numerical order gives back the original page sequence.
What size limit should I use for email?
Most mail systems cap an entire message at 20–25 MB, and encoding an attachment adds roughly a third. A 10 MB limit per part is comfortable; 15 MB is usually still fine.
Does splitting reduce the total size?
No. Splitting divides the document; it does not compress it. Compress the PDF first if the total matters as well as each part.
Are the parts named in a way that sorts correctly?
Yes — the number is zero-padded to the width of the total, so part 03 of 12 sorts before part 10 in any file listing.
Related tools
Split PDF — Extract pages or ranges (e.g. 1-3,5,7-9) into a new PDF.
Compress PDF to Size — Bring a PDF under an exact byte target such as 100 KB, 200 KB or 2 MB.
Compress PDF — Shrink a PDF by re-rendering each page to a JPEG at a chosen quality and resolution.
Merge PDFs — Combine multiple PDFs into one, with reordering.
PDF to ZIP — Export every page as its own file inside one archive.
Split PDF by Text — Start a new file wherever a page contains a phrase — one invoice per file.
Organize PDF — Reorder, rotate and delete pages from thumbnails, then export.
More PDF tools
Image to PDF — Combine images into a single PDF (auto / portrait / landscape).
PDF to Images — Render PDF pages to PNG or JPG images you can download.
Merge PDFs — Combine multiple PDFs into one, with reordering.
Split PDF — Extract pages or ranges (e.g. 1-3,5,7-9) into a new PDF.
Rotate PDF — Rotate all pages or a selection by 90/180/270°.
Organize PDF — Reorder, rotate and delete pages from thumbnails, then export.
Add Page Numbers — Stamp page numbers onto a PDF (position, format, start).
Watermark PDF — Add a diagonal text watermark to every page.
Crop PDF — Trim margins from every page via the crop box.
PDF to Text — Extract selectable text from a PDF as plain text or Markdown.
Compare PDFs — Diff the extracted text of two PDFs line-by-line.
Encrypt PDF — Password-protect a PDF with AES-256 or RC4 encryption.
Decrypt PDF — Remove password protection from an encrypted PDF.
Compress PDF — Shrink a PDF by re-rendering each page to a JPEG at a chosen quality and resolution.
PDF Metadata Editor — View, edit or strip a PDF’s title, author, subject, keywords and producer.
Resize PDF — Rescale every PDF page to A4, Letter or another standard size, content centred.
Flatten PDF — Lock filled form fields into the page so a PDF looks the same everywhere.
PDF N-up — Print 2, 4, 9 or 16 pages per sheet, with a booklet option for folding.
Interleave PDF Pages — Merge odd and even scan passes back into one document, reversing if needed.
PDF to Single Long Page — Stack every page onto one continuous sheet you scroll instead of paging.
PDF Form Data Extractor — Pull the answers out of a filled PDF form as JSON or CSV, field by field.
Blank Page Remover — Find and delete blank pages from a scan, with a tolerance you control.
Text to PDF — Turn typed or pasted text into a paginated, downloadable PDF.
Markdown to PDF — Render Markdown — headings, lists, tables and code — as a PDF.