PDF too large to email? How to make it smaller

Updated 2026-11-04

Gmail stops attachments at 25 MB, Outlook often at 20 MB, and many upload forms at 5 or 10 MB. A PDF made from phone photos or a scanner can easily be larger than all of them. The good news: most of that size is usually easy to remove.

Why the file is big

Text and vector graphics take very little space — a 100-page text-only PDF is often under 1 MB. Size comes from images: full-resolution photos, scans saved at 600 dpi, or pages that were "printed to PDF" as pictures. A single 12-megapixel photo can weigh 3–5 MB on its own.

Compress the images, not the text

A good PDF compressor lowers the resolution of the images inside to what you actually need on screen and re-compresses them, while leaving text and vector drawings untouched. Localvert's Compress PDF tool offers three levels: Strong for the smallest file, Recommended for documents that will be read on screen, and Light when you plan to print.

For documents, around 150 dpi is perfectly readable on screen; 300 dpi is print quality. Scanned contracts rarely need more than 150–200 dpi.

When compression isn't enough

Split the PDF and send it in parts, or remove pages the recipient doesn't need with Split PDF. If you are creating the PDF from photos, reduce the photo size before building it — for example by setting a maximum width of 1600 px when converting HEIC or JPG to PDF.

For very large files, share a link from a cloud drive instead of attaching the file. Just remember that the cloud service then holds a copy.

Scanning documents the smart way

If you control the scanner, choose 150–200 dpi, grayscale for text documents and "PDF" as the output. Colour at 600 dpi produces files ten or more times larger with no benefit for reading. Phone scanning apps usually have a quality or size setting too; "medium" is almost always enough for paperwork.

Photos of documents should be cropped to the page before you build the PDF. Every centimetre of table or floor around the sheet adds bytes and makes the page harder to read.

Other things that make PDFs heavy

Embedded fonts add some size, especially for Asian languages, but rarely more than a few megabytes. Forms with many fields, attached files inside the PDF and layers from design software can also add weight. If a PDF is large but has no photos, re-exporting it from the original program with a "smallest file size" or "standard" preset often helps more than compressing it afterwards.

Check before you send

Open the compressed PDF and zoom into a page with small print or a signature. If it is still sharp at 100–150%, it's fine to send.