The short answer
100 KB is the smallest target ViaPDF accepts. Custom takes a size from 0.1 to 100 MB, so type 0.1. ViaPDF counts 1 MB as 1,000,000 bytes, which makes 0.1 MB exactly 100,000 bytes. Some portals count 100 KB as 102,400 bytes. A file that fits ViaPDF’s 0.1 MB fits theirs too.
Expect an honest answer rather than a promise. 100 KB is a very tight limit. A one-page scan or a short typed document can often get there. Several scanned pages, or pages full of photos, often cannot, and ViaPDF says so instead of handing you a file the portal will turn away.
How to compress a PDF to 100 KB in ViaPDF
- Open CompressOn the Tools tab, tap Compress, or tap Open PDF first and then pick Compress. Processing stays on your phone.
- Add the PDFChoose the file with Add PDF. You can add more than one; each file is fitted on its own.
- Choose Fit under a sizeIt is the fourth option, under High, Medium and Small: Sharpest result that fits a size limit.
- Tap Custom and type 0.1Under Target size, skip the 2 MB, 4 MB and 5 MB chips. Tap Custom and type 0.1, which is 100 KB.
- Tap CompressViaPDF tries its quality steps and keeps the sharpest one under 0.1 MB. The card shows the Original and Compressed sizes.
- Read the line under the cardUnder 0.1 MB means it fits. If the line names the smallest size the file can reach, send fewer pages or try Grayscale first.
- Save or ShareThe result is Compressed.pdf. Open it once to check that the text is readable. The first export is free.
Do this job on your phoneFree to download. The first export is free. Then pay once. Google Play shows your local price. The file stays on the device until you share it.
What the line under the card means
- Under 0.1 MB (with a check mark): the file fits. Save or Share it.
- Already under 0.1 MB: the file was small enough before you started. Send the original as it is.
- “Application form.pdf can’t get under 0.1 MB. The smallest it gets is 240 KB.”: even the strongest step is too big for 100 KB. The next section has what to do.
The file name and the numbers are examples. Your file will differ.
If it can’t get under 100 KB
At that point Compress has done what it can. What is left is to change the file itself:
- Send fewer pages. If the form asks for one page, such as a certificate or the signed page of a form, extract that page with Split, then fit the shorter Split.pdf under 0.1 MB. For a 100 KB limit, one page is often the realistic size of a scan.
- Drop the colour. If the portal does not need colour, run Grayscale, then fit the Grayscale.pdf it creates. Grayscale does not promise a smaller file, so read the line under the card again.
- Upload in parts. If the portal takes more than one file, split the PDF into parts (each Split run saves one PDF), add them all to Compress and fit them together. Each file is fitted under 0.1 MB on its own.
If none of that gets under 100 KB, the limit is too tight for this document. Check whether the portal has a separate route for longer files, or ask the office that runs it. A file forced under 100 KB at any cost can become unreadable, and an unreadable scan gets rejected too.
Why not just zip it? Android has no built-in setting that shrinks a PDF. File managers such as Samsung My Files can compress a file into a ZIP archive, but a form that asks for a PDF will not take a ZIP.
Which PDFs can reach 100 KB
- Typed documents, such as a letter exported from a word processor, are often under 100 KB already. If the line says Already under 0.1 MB, send the original: it keeps its selectable text, and a compressed copy does not.
- A one-page scan has a fair chance. Zoom into the result and check that small print, stamps and signatures are still readable.
- Multi-page scans and photos are where 100 KB usually falls short. Each page is an image, and a handful of images rarely fits in 100 KB at a readable quality.
For 1 MB, 500 KB or 200 KB, see compress a PDF to 1 MB or less. For the common 2, 4 and 5 MB limits, see compress a PDF to 2 MB, 4 MB or 5 MB.
Compress a PDF to 100 KB FAQ
Can I set a limit below 100 KB, such as 50 KB?
No. Custom accepts 0.1 to 100 MB, so 0.1 MB (100 KB) is the lowest target. When the file fits, the card shows its exact Compressed size, so you can see whether it also meets a lower limit.
Will the text still be readable?
Often, for a page or two. A 100 KB limit forces ViaPDF to drop detail, more so on a long scan. Open Compressed.pdf and zoom in on the small print before you send it.
Can I select the text in the compressed file?
No. Compress writes each page as an image. If the form needs searchable text, run OCR, tap Save searchable PDF, and fit that file.
Is my file uploaded?
No. Compression runs on your phone. The file leaves the device only when you tap Save or Share.
Is it free?
Downloading is free and the first export is free. After that, a one-time purchase unlocks unlimited Share and Save. Google Play shows your local price.