A limit of 100 KB (or 200 KB, or 500 KB) is common on forms that expect a single document: an ID card, a certificate, a signature page. It is also one of the hardest limits to meet, because it leaves very little room for each page.
Is 100 KB realistic for your PDF?
Divide the limit by the number of pages. That is your budget per page:
| Limit | 1 page | 3 pages | 10 pages |
|---|---|---|---|
| 100 KB | 100 KB | about 33 KB | 10 KB |
| 200 KB | 200 KB | about 67 KB | 20 KB |
| 500 KB | 500 KB | about 167 KB | 50 KB |
A page that is mostly a photo or a scan needs room to stay readable. The smaller the budget per page, the more the images have to be reduced, and the softer the text in them becomes. One or two scanned pages under 100 KB is often possible; ten scanned pages under 100 KB usually isn’t, at least not while staying readable.
A PDF that is already mostly text (exported from a word processor, for example) is often small to begin with. If it is still above the limit, the cause is usually embedded fonts or images, and compression can only remove so much.
Steps with PDFTuck
- Open PDFTuck and tap Select PDF. Android’s file picker opens; choose the document.
- Under the target size, choose Custom and type
100with KB selected. (For 200 KB or 500 KB you can simply tap the preset.) - Tap Compress PDF. PDFTuck tries up to seven quality settings, measures the real size of each result and keeps the best-looking one that is at or under 100 KB.
- If it fits, you’ll see Ready to upload ✓ with the old and new size. Open Preview and zoom in on the text you care about: names, numbers, stamps.
- Tap Save PDF. Android’s “Save as” dialog suggests a name such as
certificate_100KB.pdf.
PDFTuck counts 1 KB as 1,000 bytes. If the portal counts 1 KB as 1,024 bytes, its limit is slightly larger, so typing the portal’s number is safe either way.
When it won’t go under 100 KB
If PDFTuck can’t reach the limit while keeping the pages readable, it says Best readable result and shows the size it did reach. You then have three honest options:
- Use this file if the portal limit turns out to be larger than you thought, or if you’re close and want to try.
- Try stronger compression. The app warns that this may noticeably reduce readability. Check the preview carefully.
- Change the document. This usually works best:
- Remove pages the form doesn’t ask for (instructions, blank backs of pages).
- If the portal accepts several files, split the document and upload the parts separately.
- Scan again at a lower resolution or in black and white, if your scanner app offers it. Clean, high-contrast scans compress far better than photos taken at an angle in poor light.
What changes in a 100 KB copy
To reach a very small target, pages may be turned into images. Then the text is no longer searchable or copyable, and links, form fields and digital signatures are not kept. Your original PDF is never changed, so you can always go back to it. If a form needs a valid digital signature, compress before signing, or ask whether the portal accepts a larger file.
Password-protected files
If the PDF needs a password to open, PDFTuck can’t compress it. Remove the password first with a tool you trust, then compress the copy.