Visa portals are unforgiving. The limits are low, the error messages are vague, and the documents involved — passports, bank statements, sponsor letters — are exactly the sort of thing you want to be legible when a human being finally opens them.
Typical limits
They vary by country and by portal, but the common bands are:
Read the instructions carefully, because some portals cap each file *and* the total. Getting eight documents under 500KB each is no help if the combined submission has to fit in 2MB.
How to do it
The compressor runs in your browser. Your passport scan and your bank statements are never sent anywhere — which for this category of document should be the first thing you check about any tool you use.
Aim below the limit, not at it
If the cap is 500KB, target 450KB. Portals differ on whether "500KB" means 500,000 bytes or 512,000, and some count a few bytes of metadata you cannot see. A file at 499KB that gets rejected on a technicality at 2am the night before a deadline is a bad experience. Leave yourself room.
What the officer has to be able to read
This is where people go wrong. Compression that hits the size limit but renders your document unreadable does not save you time — it gets your application queried or returned.
Check these specifically after compressing:
Open the compressed file, zoom to 100%, and look at those specific areas. If any of them have gone soft, you compressed too far.
When compression is the wrong answer
Scan at a lower DPI instead. If you are scanning the documents yourself, do not scan at 600 DPI and then compress hard. Scan at 200 to 300 DPI in the first place. The result is a smaller file that is *more* readable than a heavily compressed high-DPI scan, because you never introduced the compression artefacts.
Scan in greyscale, not colour. Unless the portal specifically asks for colour, a greyscale scan of a text document is roughly a third of the size for no loss of legibility. Most scanner apps have this setting one tap away.
Split multi-page bundles. If the portal takes documents individually and your bank statement bundle is over the cap, [split it](/split-pdf) and upload the pages separately where allowed.
Photographing documents with a phone
Many people photograph rather than scan. If you do:
Use your phone's built-in document scanner (Notes on iOS, Google Drive on Android) rather than the plain camera. It flattens perspective, crops to the page edge and applies contrast correction, all of which produce a smaller and more readable file than a raw photo.
Then convert the images with JPG to PDF and compress if needed. A raw 12-megapixel camera photo of a document is typically 4MB and full of information about your desk; a scanner-app capture of the same page is a few hundred kilobytes of just the document.