Why is my PDF still large after compressing it?

On its default Lossless setting, HerePDF's compress tool only re-saves the file, which removes minor redundancy and cannot shrink images. If the size comes from photos or scans, choose Balanced or Smallest: they recompress the JPEG images at a lower resolution and quality, which is where the size usually is. Black-and-white fax-style scans are already compact and are left as they are.

What is a typical email attachment limit?

Limits differ by provider and change over time; 25 MB is a common figure for consumer email, and many upload forms allow much less. Check the limit that applies to you before choosing a method.

Is splitting a PDF a real fix?

It is often the most reliable one. Sending two files that each fit under the limit loses nothing, whereas every method that reduces quality trades away something about the document.

Guide

PDF Too Big to Email? What Works, in Order of Effort

The email bounces, or the portal says "file too large." Before trying random tools, it helps to work from the cheapest, safest fix to the most invasive one, because each step down the list gives up something.

Step 1: find out why it is big

Almost always, the size is images. A 40-page scan is 40 photographs; text-only pages are tiny by comparison. Why your PDF is so large goes through what occupies space and which fixes are real. If your file is text-based and still huge, embedded fonts or leftover objects from editing may be the cause — but if it is a scan, none of that applies.

Step 2: remove pages you do not need

This costs nothing in quality. Blank pages, cover sheets, duplicate pages and appendices the recipient does not need all add weight. The organize tool lets you delete pages and see the result before you save.

Step 3: compress it

The compress tool has three settings. Lossless re-saves the file and can shave off some redundancy, which occasionally helps on documents that were edited many times. On a scan or a photo-heavy file, choose Balanced (up to 150 DPI) or Smallest (up to 100 DPI) instead: they recompress the JPEG images, which is usually where the size is. That is a real loss of detail, so keep the original. If the file's size is in text, fonts or images that are not JPEGs, no setting will shrink it much, and that is expected, not a fault.

Step 4: split it

If the content has to stay at full quality, send it in parts. The split tool extracts page ranges into separate files, and two attachments that each fit the limit lose nothing. Name them so the order is obvious. How to split a PDF without uploading it covers the details.

Step 5: lower the resolution (last resort)

If Smallest is still too big, or the scan's images are in a format the compress tool leaves alone, you can get to fewer pixels per page another way: with the PDF to image tool — export the pages as JPEG at a lower DPI — and then bring them back together with the image to PDF tool. This works, and it can cut a scan dramatically, but know what it costs: the pages become pictures, so any selectable text is gone; the image quality drops with each lossy step; and small print may no longer be legible. Check the result at the size your reader will view it. PNG or JPEG? Choosing a format and DPI helps choose the settings.

How to tell which kind of file you have

Open the PDF and try to select a sentence. If the text highlights, the pages are mostly text and the file should be small; a large size then points at embedded images, fonts, or history from many edits. If nothing highlights, it is a scan, and its size is simply the number of pages multiplied by the size of each page image. A rough test is to divide the file size by the page count. Under about 100 KB per page suggests text; over about 1 MB per page suggests images. Those numbers are a rule of thumb, not a specification, but they tell you which of the steps above are worth your time.

What a good result looks like

For a text-based document, deleting unneeded pages and re-saving is often all it takes. For a scan, a 10-page file at roughly a megabyte a page becomes about 10 MB, which fits under most consumer email limits but not under a strict upload form. If the limit is tight, you will be choosing between splitting and reducing resolution, and the right answer depends on whether the reader needs to zoom in on fine print. A legal exhibit needs every pixel; a receipt for an expense claim usually does not.

A note on online compressors

Many web tools promise dramatic size reductions. They achieve them by uploading your file to a server, re-encoding the images at lower quality, and sending it back. That is the same thing step 3's Balanced and Smallest settings do, only on someone else's server, with your document leaving your device on the way. If the file is sensitive, it is a poor trade for something you can do locally. Client-side vs upload-based PDF tools sets out where each approach makes sense.

Check the result before you send it

Whatever you did, open the smaller file and zoom in on the smallest text and any signatures or stamps. Check that pages are still in order and none were lost. It takes a minute and prevents the worse outcome, which is sending a file the recipient cannot read and having to start over after a deadline.

Choosing

If you can afford to send two files, do that. If not, delete what is not needed, then compress: Lossless first, and Balanced or Smallest if it is a scan or full of photos, checking that the result is still readable at the size your reader will see it. Whichever you choose, everything here runs in your browser, so a sensitive file never has to be uploaded just to make it smaller.