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Quick answer
To compress a PDF to 150KB, open Compress PDF, add your file, choose Extreme and click Compress PDF. The size is shown before you download. Two scanned pages, or a single page with a photo on it, usually fit under 150KB.
How to compress a PDF to 150KB in 3 steps
Add your PDF
Open Compress PDF and drop in your file. PDFs up to 200 MB work, including scans.
Choose Extreme
Extreme is the best starting point for a 150KB target. The tool shows the original and compressed sizes, so you can check the result straight away.
Check the size and download
If the new size is under 150KB, download it. If not, see the fixes below.
What fits in 150KB
Text barely adds to a PDF's size. Scanned pages and photos are what make it heavy. As a rough guide:
Swipe to compare →
| Your PDF | Level to try | Under 150KB? |
|---|---|---|
| Text-only document | Light or Moderate | Usually |
| 1–2 scanned pages | Extreme | Usually |
| A form with a photo attached | Extreme | Usually |
| 3 or more scanned pages | Extreme, then trim pages | Sometimes |
If your PDF is still over 150KB
- Try the next level up, up to Extreme.
- Remove blank or unneeded pages with Delete PDF pages, then compress again.
- If it is a scan, re-scan at 150 DPI in grayscale. It makes a much smaller file to begin with.
- Still too big? Split the PDF into two files and upload each one if the form allows it.
Scan settings that land under 150KB
The easiest way to hit 150KB is to create a smaller file from the start. If you are scanning a document for a 150KB limit:
- Resolution: 150 DPI is plenty for reading and printing. 600 DPI makes files several times bigger for no visible gain.
- Color: grayscale, or color if a photo is included.
- Pages: only the pages that are asked for.
- Phone scans: use the Notes app on iPhone (Scan Documents) or Google Drive on Android, which crop and flatten pages automatically.
How to check a PDF's size in KB
- iPhone: in the Files app, touch and hold the PDF and tap Get Info.
- Android: in Files by Google, tap the three dots next to the file and choose File info.
- Mac: select the file in Finder and press Command-I.
- Windows: right-click the file and choose Properties, or switch File Explorer to Details view.
Compress PDF also shows the original and compressed sizes on screen, so you can check before you download.
Where you'll run into a 150KB limit
- Application forms that combine a photo and a signature on one page.
- Scholarship and financial aid documents uploaded one at a time.
- Insurance and benefits portals with per-file caps.
- Scanned receipts for expense reports.
Frequently asked questions
How do I compress a PDF to 150KB for free?
Open Zappy Compress PDF, add your file, choose Extreme and click Compress PDF. The new size is shown before you download, so you can confirm it is under 150KB.
Can every PDF be compressed to 150KB?
Not always. Long scanned documents may not fit in 150KB even on Extreme. Remove pages you don't need or split the file into parts.
Will the text still be readable?
Yes. Compression shrinks images and scans, not text, so typed words stay sharp at every level.
What if my form says 150KB maximum?
Aim for 140KB or less to leave a small margin, since some systems count file sizes slightly differently.
Is 150KB the same as 0.15 MB?
Roughly, yes. Upload forms usually treat 1 MB as 1,000 KB, so 0.15 MB is about 150KB.
Does it work on iPhone and Android?
Yes. Open Compress PDF in Safari or Chrome and choose the file from Files or your Downloads.
What happens to my file?
It is compressed on our server and deleted automatically afterwards. It is never shared.