Why 5 MB is such a common limit
Five megabytes is a frequent ceiling on official and semi-official forms: tax and benefits paperwork, permit and license applications, insurance claims, immigration supporting documents and court or council submissions. It's also a size where many people start to worry about email. Some mail systems and recipients' inboxes still struggle with large attachments, and a 5 MB PDF travels far more reliably than a 20 MB one.
At this size, quality is rarely the problem. A multi-page scanned document can usually fit while every page stays clear enough to print or to zoom into the small print, which matters when an official is checking dates, signatures or reference numbers.
Bundles of documents in one file
Government forms often want everything in a single upload: an application, ID pages, proof of address, bank statements and a signed declaration. Each one scanned at high resolution can be several megabytes on its own. The practical order is to merge first and compress second: combine the files with “Merge PDF”, then compress the merged PDF to 5 MB so the engine can balance the budget across all pages.
If an office asks for separate attachments, each under 5 MB, select all of them here instead. Each PDF gets its own 5 MB target and they download together in a ZIP.
What the engine changes, and what it doesn't
ConvertirDocs works on photos: JPEG images and 8-bit color or grayscale photos inside the PDF. It lowers their quality step by step and stops once the file fits. Text and vector graphics are never recompressed, so typed text stays sharp, selectable and searchable. Hidden extras such as embedded page thumbnails and XMP metadata are removed.
Images with transparency, 1-bit black-and-white images, indexed-color, CMYK, JPX and JBIG2 images are left as they are, because recompressing them could damage them. If those make up most of your file, 5 MB may not be reachable. You'll then get the smallest version possible and an explanation, and you can consider splitting the document with “Split PDF”.
Sensitive paperwork stays with you
Tax returns, bank statements and passport scans are not files you want to hand to a stranger's server. Here, compression runs in your own browser: the PDF isn't uploaded and nothing is stored. It's free, with no account, no email and no watermark, and you can use it as many times as you need.