A 20 MB PDF is fine until you try to send it. Email services typically bounce attachments around 10–25 MB, and slow uploads or strict portals make oversized documents a headache. Compressing the file is the fix, but nobody wants a PDF that turns text and images into mush.
ThothBox's Compress PDF tool shrinks your file in the browser, with controls that trade a little size for a lot of clarity. Your document stays on your device, so compressing even a sensitive file is painless.
Shrinking a PDF usually means re-encoding the images inside it, which is where most of the file weight lives. More aggressive compression produces a smaller file, but at some point fine detail softens. The trick is finding the level where the file fits your destination and still reads clearly on screen.
For text-heavy documents, compression can be aggressive with little visible effect, because sharp text survives very well. For image-heavy pages, like scanned brochures or photo manuals, you will want a gentler setting so pictures keep their detail.
Email is the most common trigger: many providers hard-limit attachments at 25 MB, and some company mail servers stop at far less. File-upload forms for government, banking, or job applications often cap PDFs at a few megabytes too. Knowing the limit in advance tells you how far you need to compress.
Once you know the target, compress once, check the resulting size, and adjust if the file is still too big or the quality dropped more than you'd like.
Yes — choose a lighter compression level and the file shrinks with only minor, often invisible, changes.
Yes, the Compress PDF tool is free and needs no account.
No. Compression happens entirely in your browser, so your PDF never leaves your device.
It depends on the file. Image-heavy PDFs shrink dramatically; already-compressed text documents gain less.
Yes — text survives compression well, and a moderate setting keeps everything clearly legible.