How to make a PDF small enough to email

When an attachment will not send, size is the first thing to check. Here is how to find out what the limit is, which PDFs can shrink and which cannot, and what compressing a PDF costs you.

Last checked 2026-10-14.

Compress a PDF

First, find out what the limit is

Your mail service sets a limit on what you can send, and your recipient's service has its own, which you cannot see. The two you are most likely to meet are published by the companies themselves.

Gmail. Google's help page gives 25 MB (megabytes) as the sending limit for a personal Gmail account, and says Gmail removes an attachment over the limit and adds it to the email as a Google Drive link instead. For work and school accounts, the administrator sets the limit.
Outlook for Windows. Microsoft's support article documents a default limit of 20 MB for internet email accounts, counted across all the attachments on a message rather than per file. For an Exchange mailbox the default is 10 MB, and the administrator can change it.

Two habits help with those numbers. First, add up everything on the message: three 9 MB attachments are 27 MB, and no single one of them looks like the problem. Second, leave room. Email carries attachments as text, and the standard that defines this, RFC 2045 (Request for Comments, the series that documents internet standards), turns every three bytes into four characters. That makes an attachment about a third bigger in transit. Help pages do not always say whether the limit counts the file or the encoded message, so aim for comfortably under the number rather than exactly at it.

Which PDFs can shrink, and which cannot

A PDF is big for a reason, and the reason decides what can be done about it. A PDF exported from a word processor or a spreadsheet is mostly text and drawing instructions, and it is usually small to begin with. A PDF that came from a scanner or a phone camera is a stack of photographs, one per page, and that is where the megabytes come from.

Compression works on the photographs. Our tool redraws each page at a lower resolution and saves it as a JPEG (Joint Photographic Experts Group) image, which is a smaller way to store a picture. A file with no pictures in it gives that process very little to work with.

Here is how that looked on our own test files. They are small and clean, so treat them as an illustration and not a promise about yours. A one-page scanned invoice of 267 KB (kilobytes) came to 62 KB at Medium and 18 KB at Strong, which is 77 and 93 percent smaller. Three text-only test files of 1 to 2 KB did not shrink at any level, and the page handed each one back unchanged.

What the three levels do

Light keeps your pages exactly as they are and rewrites the file's internal structure more compactly. Text stays selectable. It helps a file with a messy structure and does very little for a PDF made of photographs: on our scanned test page it found nothing to save and returned the original.
Medium redraws every page as a picture at 110 dpi (dots per inch) and saves it as a JPEG.
Strong does the same at 72 dpi. That is enough to read on a screen and soft on paper.

Medium and Strong have a cost you should know about before you send. Every page becomes a picture, so the text can no longer be selected, searched, or copied. Links, form fields, and bookmarks are gone, and a digital signature on the original does not carry over to the new file. Your original is untouched, so keep it.

When it cannot help, you get your file back

A compressor should never hand you something bigger than it was given, and rebuilding a mostly-text page as a picture can do exactly that. On our text-only test files, Medium would have turned files of 1 to 2 KB into files of 24 to 41 KB. So when the result would not be smaller, the page gives you your original file, unchanged and under its own name, and says so.

A message that says there is nothing to save is a real answer: the file is already about as small as it gets. At that point the way forward is a different route to the same goal, and the last section of this guide lists several.

What the free plan takes

The free plan takes PDFs up to 10 MB each, and up to 3 files at a time. A file over 10 MB is turned away with a message before any work starts, so a 30 MB scan cannot be compressed here.

If the combined size of several attachments is what puts you over, add up to three PDFs together. Each is compressed on its own, and the page reports the total before and after for the batch. Every tool is free every day up to a daily cap, and the counter under the tool shows how many runs are left today.

When to use something else

We would rather say this than have you send a file that is worse than the one you started with:

The PDF is over 10 MB. The free plan will not take it, so skip compression and send a link instead. Gmail does this for you when an attachment is over its limit, as described above, and Microsoft's error message for an oversize attachment in Outlook says to try putting the file in a shared location and sending a link.
The reader needs to search, select, or copy the text, or fill in a form. Medium and Strong are the wrong choice. Try Light, or take only the pages you need with Split PDF, because a PDF with fewer pages is smaller. Our guide to splitting covers how.
It is a signed or official document. A rebuilt file is a new document, not the one that was signed. Send the original by link.
It will be printed. Strong in particular looks soft on paper. Use Medium, and open a page at full size before you send.
It came from a scan you can redo. A scan at a lower resolution is smaller from the start. If you plan to read it with OCR (optical character recognition) later, keep it near 300 dpi, as our scanning guide explains.

Questions people ask

What size should I aim for?

Comfortably under the lowest limit that applies, remembering that every attachment on the message counts and that email makes attachments about a third bigger in transit. The published figures are 25 MB for a personal Gmail account and 20 MB for Outlook with an internet email account, and your recipient's service may be lower.

Why did I get my own file back?

Because the compressed version would not have been smaller. That is common for PDFs that are mostly text. The message on the page says whether the file was already small or whether rebuilding it would have made it bigger.

Can the person I send it to still select the text?

Only if you used Light. Medium and Strong turn each page into a picture.

Is my PDF uploaded?

No. The file is read and rebuilt inside your browser tab, and the page is only allowed to talk to its own site. You may see one small request to upfrontpdf.com that counts the visit. It carries the page name and nothing from your file, and the privacy page says exactly what is counted.

Is it free?

Every tool is free every day, up to a daily cap, and there is no account to make. The free plan takes up to 3 files at a time, 10 MB each. The pricing page has the details.

Try it

It runs in your browser, so the file is never uploaded. The page shows the size before and after, so you can see at once whether it helped.