How to Make a PDF Smaller for Email

Email attachment limits

Each email service caps how much you can attach to one message. These are the limits stated on the providers' own help pages:

• Gmail: 25 MB for personal accounts. If your attachments go over the limit, Gmail swaps them for a Google Drive link. For work and school accounts, the administrator sets the limit.
• Outlook.com: 20 MB. Microsoft notes that this includes both the attachments and the email itself.
• Outlook with a work (Exchange) account: 10 MB by default, but your organisation's administrator can change it.
• Yahoo Mail: 25 MB for all attachments in one message, for both sending and receiving.

The limit that matters is the smaller of yours and your recipient's. A 22 MB PDF might leave Gmail fine and still bounce from a company mailbox that only accepts 10 MB. Attachments are also encoded as text while they travel, which makes them roughly a third larger in transit, so a file just under the limit can still be rejected along the way.

A practical rule: if you don't know what the other side accepts, aim for under 10 MB. For upload portals and application forms the limit is often much lower — 100 KB to 2 MB is common — and the same techniques work there too.

Why some PDFs are so big

The size of a PDF depends far more on what's inside it than on the number of pages.

• Typed documents (exported from Word, Google Docs or an invoicing app) store letters as text and fonts. A 20-page report can easily be a few hundred kilobytes.
• Scanned documents are different: every page is a full photo of the paper, often in colour at a high resolution. A single scanned page can weigh more than an entire typed report.
• Phone photos turned into PDFs are the heaviest of all. Modern phone cameras take very high-resolution pictures, and each one becomes a page at full size.
• Embedded images and fonts — logos, charts, high-resolution product photos — add up quickly in brochures and presentations.

So the first question is: is your PDF mostly text, or mostly pictures? That decides which method below will actually help.

Step by step: compress the PDF to a target size

Compress PDF is the best place to start for any PDF.

1. Open Compress PDF and choose your file. It's opened on your device and not uploaded anywhere.
2. Try Recommended first. It rewrites the file more compactly and removes metadata without changing anything you can see, and text stays selectable. On typed documents the saving is often modest, because most PDFs are already compressed internally.
3. If that isn't enough, switch to Target size and enter the maximum size in KB. For email, something like 9000 (just under 9 MB) leaves comfortable room under every limit above. For a portal with a strict cap, enter that number instead, for example 200 or 500.
4. Click Compress PDF, compare the before and after sizes, and download.

Target size mode tries a lossless rewrite first. If that doesn't reach your target, pages are saved as compressed images. That works very well for scans and photos, but it means text in those pages can no longer be selected or searched — keep your original if you need that. If the target can't be reached at all, you get the smallest version possible and a clear note saying so.

Ready-made presets exist for common form limits: under 100 KB, 200 KB, 500 KB and 1 MB.

For scans: switch to grayscale or black and white

If your PDF came from a scanner or a phone scanning app, Compress Scanned PDF usually beats general compression, because it's built for exactly that kind of file.

1. Choose your PDF. Each page is checked to see whether it's a scan or contains real text; text pages are left untouched by default.
2. Pick a colour mode. Black & white gives the smallest files and the crispest look for typed or printed text. Grayscale keeps signatures, stamps and pencil marks looking natural. Keep Colour only for photos, highlighter or coloured forms.
3. Pick a resolution. 150 DPI suits most documents for reading on screen and normal printing. Use 200–300 DPI for very small print, or 100 DPI when the limit is very tight.
4. Leave Whiten paper background and Remove dark scanner borders on. Grey, yellowed paper and dark edges take up space as well as looking messy.
5. Optionally set a target size in KB, then compress, check the before/after preview and download.

For a one-click version, Convert PDF to Grayscale applies sensible grayscale settings for you.

Split the file or remove pages you don't need

Sometimes a PDF is big simply because it's long. Two options don't reduce quality at all:

• Remove unneeded pages. Blank pages, duplicate scans and cover sheets add weight. Delete them with Organize PDF.
• Split into parts. Split PDF can cut a file into page ranges (for example 1-20 and 21-40) or every N pages. Send the parts in separate emails and number the subjects, such as "Contract — part 1 of 2".

Splitting copies pages without re-rendering them, so text and image quality stay exactly as they were. It's the best choice when you can't afford any loss in quality, such as for detailed drawings.

Starting from photos? Build a small PDF from the start

If you haven't made the PDF yet — you only have photos of the pages — create it at the right size instead of compressing afterwards. JPG to PDF under 500 KB combines your photos into one PDF and recompresses the images only as much as needed to stay under the limit. There are also versions for under 200 KB and under 100 KB, which are common caps on application forms.

Take the photos in good, even light and fill the frame with the page. Clean, well-lit pages compress much better than dim, grainy ones, because there is less noise for the compressor to preserve.

Which method should you use?

Tips that don't need a tool

Send a link instead. For very large files — a full architectural set or a long photo-heavy report — upload the file to a cloud storage service you already use, such as Google Drive, OneDrive, iCloud Drive or Dropbox, and send a share link. Microsoft recommends this for files over Outlook's limit, and Gmail does it for you automatically. Check the link's sharing permissions so only the right people can open it.

Don't expect ZIP to help much. It's natural to think zipping will shrink a file, but PDFs are usually compressed already. The text and drawing instructions inside are typically packed with the same kind of compression ZIP uses, and images are usually stored as JPEG, which is compressed too. Compressing data that is already compressed saves very little, so a 30 MB PDF will still be close to 30 MB inside a ZIP. ZIP is useful for bundling several files into one attachment, not for shrinking a PDF.

Re-export instead of re-scanning. If you made the PDF yourself from Word, PowerPoint or Google Docs, export it again with a smaller image setting (often called "minimum size" or "optimise for web"). This is often cleaner than compressing afterwards.

Check the result before you send it. Open the compressed file, zoom into the smallest text and make sure signatures, stamps and numbers are still easy to read. A file that fits but can't be read will only come back to you.