# Why Won't My PDF Compress to 100KB?

A 100KB limit is really one number split across every page in your file. This page runs real documents through PDkef's own compressor and shows what actually happens at 1, 5 and 10 pages, so you can tell whether your file is close or genuinely won't fit.

URL: https://pdkef.com/pdf-wont-compress-to-100kb/

## A page count, not a file size, decides whether 100KB is realistic

One page gets the whole 100KB budget. Ten pages split that budget ten ways. That single fact predicts most of what happens when you try to hit a small target: a one-page form compresses comfortably, and a ten-page scan of the same form does not, even though nothing else about the document changed.

Here is why. To reach a small target, PDkef turns each page into an image, then searches for the smallest JPEG quality that still fits. If quality alone cannot get there, it steps down through five resolutions in turn, from about 108 DPI down to about 36 DPI, trying each one before giving up further detail. A typed, vector PDF skips all of this: if the file is already under the target, it is kept exactly as it is.

## What 100KB actually looks like at different page counts

Every row was produced by running the file through PDkef's own Target Size mode at 100KB.

| Document | Original size | Result at a 100KB target | Still readable? |
| --- | --- | --- | --- |
| One typed page (native PDF text) | 3.5 KB | Kept unchanged, already under target | Yes, perfectly, it was never rasterized |
| One scanned page (phone photo) | 459 KB | 100 KB, 78% smaller | Yes, crisp and fully legible |
| Five scanned pages | 2.23 MB | 100 KB total, 96% smaller | Yes, fully readable with mild softening |
| Ten scanned pages | 4.46 MB | 97 KB total, 98% smaller | Headline sharp, body paragraphs blurred |

The typed page never needed compressing at all: native PDF text is already tiny, and PDkef only rasterizes a page when a target actually requires it. The other three rows are the same scanned form at 1, 5 and 10 pages, each compressed with nothing else changed.

## A ten-page scan can hit 100KB and still be hard to read

The ten-page result above technically met the 100KB target. It also spends roughly 10KB per page, which is not enough to keep body text sharp once it has been through a search for the smallest file that fits. The form's title and field labels stayed legible; full paragraphs did not. That is the honest ceiling, not a bug in the tool: a portal asking for 100KB across ten pages is asking for something that may not stay comfortably readable, no matter which compressor you use, because the arithmetic is the same everywhere.

- **Split the document first.** If the portal accepts multiple uploads, use [Split PDF](/split/) to submit fewer pages per file, so each one gets a larger share of the size budget.
- **Check whether a higher limit is actually required.** Many forms show "up to 500KB" or "up to 1MB" once you look past the placeholder text; 100KB is frequently a default, not a hard technical ceiling.
- **Scan in grayscale at a lower resolution to start.** A black-and-white document scanned at 150 DPI grayscale is a fraction of the size of the same page scanned in colour at 300 DPI, before any compression at all.
- **Accept the trade for genuinely long documents.** A ten-plus page scan aimed at 100KB will lose some sharpness. Try 200KB or 500KB if the portal allows it; the difference in legibility is large for a small increase in size.

## Real portals, and the size caps they actually publish

Pulled from each portal's own published guidelines, not a third party's estimate.

| Portal | What it caps | Documented limit |
| --- | --- | --- |
| IBPS (bank recruitment exams) | ID proof, certificates, combined marksheet PDF | PDF only, 500 KB maximum |
| NTA UGC-NET (and similar NTA exams) | Candidate photograph upload | 10 KB to 200 KB, JPEG only |
| NTA UGC-NET (and similar NTA exams) | Candidate signature upload | 4 KB to 30 KB, JPEG only |

IBPS's own recruitment guidelines state that identity proof, certificates and the **consolidated marksheet** (candidates are told to combine every semester into a single PDF) must be uploaded as one PDF file, capped at 500KB ([ibps.in candidate portal](https://ibpsreg.ibps.in)). These caps were set for slow connections and small server quotas, and most have outlived the reason they exist, but the portals still enforce them.

The National Testing Agency's UGC-NET information bulletin specifies a 10KB to 200KB photograph and a 4KB to 30KB signature, both JPEG, quoted directly from its [published information bulletin](https://ugcnet.nta.ac.in/images/information-bulletin-for-ugc-net-june-2025-16042025.pdf).

## Try it on your own file before deciding what to do next

[Open the free PDF compressor](/compress/), choose Target Size, and enter the limit your portal actually asks for. The file never leaves your device, so there is no upload wait to find out whether it fits: you will know in seconds, and you can raise the target or split the file if it does not.

[Open the free PDF compressor](https://pdkef.com/compress/)

## FAQ

### Why can't I compress a 10-page PDF to 100KB?

A 100KB target is split across every page. Ten pages leaves roughly 10KB per page once container overhead is subtracted, which is enough for a compressor to hit the number but not enough to keep full paragraphs of body text sharp. Titles and short labels usually stay legible; dense text does not.

### How many pages can actually fit in 100KB and stay readable?

In PDkef's own measured test, one scanned page compressed to 100KB stayed crisp, and five pages sharing that same 100KB stayed fully readable with only mild softening. Ten pages was the point where body paragraphs became hard to read. Your own document's readability depends on font size and how much text is on each page, so treat five as a rough comfortable ceiling rather than a guarantee.

### Does compressing a PDF to 100KB remove the selectable text?

Yes, when the target actually requires shrinking the file. PDkef reaches a small target by turning each page into a compressed image, which means the text is no longer selectable or searchable in that page. If your file is already under the target, it is left completely unchanged, so a small typed document usually keeps its real text.

### Why do exam and government portals cap uploads at 100KB or 200KB?

Most of these limits were set years ago for slow connections and small server storage quotas. IBPS still caps combined-document PDFs at 500KB, and the National Testing Agency caps a UGC-NET photograph at 10KB to 200KB and a signature at 4KB to 30KB. The limits have mostly outlived the reason they were set, but the portals continue to enforce them.

### What should I do if my scanned document genuinely won't fit the limit?

Split it into smaller files if the portal accepts more than one upload, so each file gets a larger share of the size budget. Check whether the portal actually requires exactly 100KB or merely defaults to showing that figure. If you are scanning from scratch, use grayscale and a lower resolution before compressing rather than starting from a large colour scan.

### Is a typed PDF ever too big to hit 100KB?

Rarely. A native, typed PDF stores text as text, not as an image, so a single page is usually a few kilobytes even before compression. PDkef only rasterizes a page when the target actually requires shrinking it, so a typed document that is already small is returned unchanged rather than needlessly degraded.