How to Compress a PDF for Email (Gmail, Outlook, WhatsApp)

To compress a PDF for email, open compress PDF, choose your file, and download the smaller copy. The "Recommended" level usually cuts scanned documents by 70–95%. If you need to get under a specific limit, switch Compress by to Target size and type the maximum, for example 10,000 KB for 10 MB, or use a ready-made target like compress PDF to 2 MB. Everything runs in your browser, so the document is not uploaded anywhere along the way.

The rest of this guide covers the actual email limits, how small to go, and when splitting the file or sending a link is the better answer.

Email attachment limits

Two practical points:

• The receiver's limit matters too. If you send from Gmail to a company inbox with a 10 MB cap, the email bounces even though Gmail accepted it.
• Attachments grow when sent. Email encodes files in a way that adds roughly a third to their size. A 24 MB PDF may count as more than 25 MB. Aim for under 15–20 MB in total, or under 10 MB when you do not know the receiver's system.

Step by step: how to compress a PDF for email

1. Open compress PDF and choose the PDF. It is compressed straight away at the Recommended level.
2. Check the result size shown next to the download.
3. Need it smaller? Choose Strong (smallest file), or switch to Target size and enter your limit in KB.
4. Text document? Tick Black & white. It makes text clearer and the file much smaller.
5. Download the compressed copy and open it to check it is readable.
6. Attach the compressed file, not the original. Renaming it, for example report-email.pdf, avoids mix-ups.

On a phone, the steps are identical in Chrome or Safari. The file saves to Downloads on Android or Files on iPhone, and you attach it from there in the Gmail or Outlook app.

How small should you go?

For email, readability matters more than hitting a tiny number.

• Up to 10 pages of scans: a few MB is usually plenty. Compress PDF to 2 MB or compress PDF to 1 MB keeps text sharp.
• Long scanned reports (30+ pages): target 5–10 MB with the Target size option.
• Forms and portals: these are different. They often need 100–500 KB; see compressing a PDF under 200 KB.

What compression does to your PDF

Our compressor works by re-rendering each page as an image at a lower resolution and JPEG quality. This is very effective for scanned documents and photo-heavy PDFs, which is what most oversized email attachments are.

Know the side effects before you send:

• Text is no longer selectable or searchable. The page becomes a picture of the text.
• Links and form fields stop working.
• Digital signatures are removed. If a PDF is digitally signed (for example a signed contract, an e-stamped document, or a certificate with a DSC), compressing it this way invalidates the signature. Send the original through a link instead.
• Text-only PDFs may not shrink. A PDF exported from Word with no images is often already small. If the compressed file is bigger, the tool tells you the original is smaller, and you should send the original.

Split vs compress

Compression is the first thing to try. Splitting makes sense when:

• The file is still too big after compression, or
• Compression would make small print unreadable, or
• The receiver only needs certain parts.

To split, open split PDF and choose:

• Custom ranges, such as 1-20, 21-40, to make one file per range.
• Every N pages, such as 25, to cut a long document into equal chunks.

Send each part in its own email, and say "Part 1 of 3" in the subject so the receiver knows to expect more. If they only need a few pages, extract PDF pages saves just those into a new file, which is often the cleanest fix.

When to send a link instead

For very large or sensitive files, a cloud link is often better than an attachment:

• Gmail offers Google Drive automatically for files over 25 MB.
• Outlook can attach a file as a OneDrive link.
• Signed or original documents keep their quality and digital signatures when shared as a link.

Check the sharing permissions on the link, so only the people you intend can open it.

Compressing a PDF for WhatsApp

WhatsApp is rarely the bottleneck for PDFs, since documents can be up to 2 GB. Compression still helps when:

• The recipient is on mobile data and a 40 MB scan would take a long time to open.
• They need to forward it to an email or a portal with a smaller limit.

Always send PDFs using WhatsApp's Document option, not as a photo, so nothing is changed in transit.

Compressing several files for one email

If you are attaching several PDFs, such as certificates for a job application, it is often better to merge PDF them into one file first and then compress that once. You get one tidy attachment and one predictable size. Our guide to merging, splitting and reordering PDF pages explains the merging step.

Common mistakes

• Attaching the original by accident. Attach from Downloads and check the size in the email before sending.
• Compressing a signed document. It breaks the digital signature. Share it as a link.
• Going far below the limit. A 300 KB blurry scan is worse than a clear 5 MB one when the limit is 25 MB.
• Forgetting the receiver's limit. When in doubt, keep attachments under 10 MB.
• Compressing twice. Each pass loses more detail. If the first result is too big, go back to the original and compress once with a stronger setting.

Questions