How to make a PDF smaller for email or upload forms

Upload forms often limit files to 2 MB or 5 MB, and email attachments are commonly limited to 20–25 MB. Most oversized PDFs are large because of the images or scans inside them, not the text. Here's what actually works.

1. Shrink images before making the PDF

If you're creating a PDF from photos or scans, compress the images first. A phone photo is often 3–6 MB; resized to 1,600–2,000 pixels wide at around 75% JPG quality, it usually drops below 500 KB with little visible difference. Use the image compressor, then JPG to PDF.

2. Scan at the right resolution

For documents, 150–200 DPI is usually readable and far smaller than 300–600 DPI. Scan text-only pages in greyscale or black and white rather than colour.

3. Remove pages you don't need

Blank pages, duplicate pages and covers add size. Use delete pages or split PDF to keep only what's required.

4. Split into parts

If a portal accepts several uploads, split a large file into parts, for example pages 1–10 and 11–20.

5. Use a dedicated PDF compressor

Compressing an existing PDF re-processes the images inside it and needs specialised software. DocNova's own PDF compressor is planned; until then, the steps above usually achieve the biggest savings without sending your document to any server.

Why some PDFs are so big

A page of typed text takes only a few kilobytes. A full-colour photo of the same page taken with a modern phone can be several megabytes, because it stores millions of pixels, including the shadows and paper texture. Most oversized PDFs are really collections of large photos.

What not to do

• Don't convert a text document to images to "flatten" it. That makes it much bigger and the text can no longer be searched or copied.
• Don't over-compress forms or IDs. If an official office can't read the numbers, the upload may be rejected. Check the result before sending.
• Be careful with online compressors you don't know, especially for identity documents, bank statements or contracts, because they upload your file to someone else's server.

A quick routine for document photos

1. Photograph pages in good light.
2. Compress them to about 1,600 pixels wide at 70–80% quality.
3. Combine them with JPG to PDF on A4 with a small margin.
4. Check the file size and readability, then send.