How to compress a PDF in your browser (without uploading it)

4 Nov 2026 · Umme Salma

Email providers often reject attachments over 20–25 MB, and many upload forms cap files at 2–10 MB. Here is how to make a PDF smaller using Lime PDF, entirely on your own device.

Step by step

Open Compress PDF.
Drag your PDF onto the page or click to choose it. It loads locally — there is no upload bar because nothing is uploaded.
Pick a level: lighter compression keeps text and images crisp; stronger compression shrinks images further.
Click compress and download the new file. Compare the size shown before and after.

Why some PDFs shrink a lot and others barely change

A PDF's size is mostly made of embedded images and fonts. Scanned documents are essentially stacks of photos, so reducing image resolution can cut them by 70% or more. A PDF that is mostly typed text is already compact, so savings will be small — that is normal, not a fault.

Tips for the best result

For scans meant for reading on screen, around 150 DPI is usually plenty.
If you only need some pages, use Split PDF first — removing pages is the biggest saving of all.
Photos you plan to turn into a PDF can be shrunk first in Lime Images, then combined with JPG to PDF.
Always keep your original until you have checked the compressed copy.

Choosing a compression level

There is no single "right" setting, so think about where the file is going:

Email attachment: start with lighter compression. If the file is still over the limit, run it again on the stronger level.
Government or job portal with a strict cap (often 2–5 MB): use stronger compression, then zoom in on the result to check that small print and signatures are still readable.
Printing: compress as little as possible. Printers show the loss of image detail far more than screens do.
Archiving: keep the original. Compression throws away image detail, and you cannot get it back later.

Checking the result properly

Open the compressed file and scroll through every page, not just the first.
Zoom to 200% on the smallest text, any stamps, and any signatures.
If it is a form, check that the filled-in fields are still visible.
Compare file sizes. If the saving is under about 10%, the file was already efficient. Try removing pages instead.

If the file is still too big

Combine tools. Split a long report into parts with Split PDF and send them separately. Delete blank or duplicate scan pages with Rotate & reorder. If your scanner produced enormous colour images of black-and-white pages, re-scanning in greyscale at a lower resolution often beats any compression setting.

Why doing it in the browser matters

The PDFs people need to shrink are often the sensitive ones: payslips for a mortgage application, ID scans, medical letters, signed contracts. Many compression websites upload these to a server. With Lime PDF the file stays on your device the whole time, and you can confirm it by turning off your internet after the page loads. The tool keeps working. More on this in Why our PDF tools never upload your files.

Very large files

Because the work uses your device's memory, a several-hundred-megabyte scan can be slow on a phone. Use a laptop or desktop for those, close other tabs, or split the file first. The LimePDF desktop app, coming on 15 Nov, is designed for big files.