Free · runs in your browser · the PDF is never uploaded
Compress a PDF to 150 KB
Short answer
Use the compressor below, already set to 146 KB so it passes a 150 KB limit either way the portal counts. It tries a lossless rebuild first, then lowers resolution until the file fits. One page stays sharp; about four to five plain pages usually fit at the lowest setting.
What fits in 150 KB
- Comfortably: One page at good quality, or two plain text pages.
- At the limit: About four to five plain pages at the lowest setting.
150 KB shows up on some government and university upload fields that sit between the common 100 KB and 200 KB caps.
For a single certificate scan, 150 KB usually leaves more resolution headroom than 100 KB, so small stamps and seals stay clearer.
“Good quality” here means around 100 DPI, which looks sharp on a screen. These are rough guides, not promises: a page of plain text compresses far better than a colour photo, so check the preview.
How to compress a PDF to 150 KB
- 1
Drop your PDF into the compressor above, or tap it to choose a file. It’s already in Target size mode at 146 KB.
- 2
Press Compress. A lossless rebuild runs first. If the file is still too big, the pages are re-rendered at lower resolutions, from 150 DPI down to 50 DPI, until it fits.
- 3
Check the preview of the first pages. Zoom in on the small print, such as dates, ID numbers and stamps, because that’s what blurs first.
- 4
Download the file and check its size on your device before uploading. On Windows, right-click and choose Properties; on a Mac, use Get Info. Compare the size in bytes with the limit.
- 5
Upload it. If the portal still says the file is too big, run the compressor again on the original with a slightly lower target.
Why the tool is set to 146 KB, not 150 KB
Kilobytes are counted two ways. Some websites treat 1 KB as 1,000 bytes; others, and this compressor, treat it as 1,024. A file the compressor calls “150 KB” is 153,600 bytes, about 2.4% more than 150,000, and a strict portal will reject it.
146 KB in the tool is 149,504 bytes, which is under 150 KB by either definition. You lose almost nothing in quality and avoid the most common “file too large” rejection.
If it won’t get down to 150 KB
The compressor stops at 50 DPI, because below that the text stops being readable. If even that pass is too big, you get the smallest readable file and a message saying so, instead of a file that technically fits but that nobody can read. These help:
- Crop to the document edges with Crop pages before compressing.
- Remove blank pages with Delete pages.
- Start from the original, not a file that was already compressed.
- Split the document if the portal has more than one upload field. Split PDF breaks it into parts you can compress separately.
Limits worth knowing
- Re-rendered pages become images with an invisible text layer. Search and copy keep working, but accented and non-Latin characters can be dropped from that layer.
- Large or image-heavy PDFs take a while, because each pass re-renders every page on your device.
- Password-protected PDFs have to be unlocked first.
- A portal can reject a file for reasons other than size, such as the file type or characters in the file name.
Frequently asked questions
How do I compress a PDF to 150 KB?
Use this page — the compressor is pre-set to 146 KB. Drop the file, press Compress, check the preview, then download.Why 146 KB instead of 150 KB?
Some portals count 1 KB as 1,000 bytes. 146 KB in the tool stays under 150,000 bytes either way.Does this upload my PDF?
No. Compression runs in your browser.
Guides for upload limits
- PDFs for government formsFrom phone photo to a PDF that passes the portal’s size limit, plus what you can and can’t hide.
- Exam application documentsMake a reusable “upload kit” of your certificates at the sizes exam forms ask for.
- Job and onboarding documentsPayslips, certificates, relieving letters and ID for HR portals, sized and checked.
- Visa application documentsUnlock bank statements, merge by category and get each file under the upload limit.
- PDF upload size limitsTypical caps for email and portals — and how to shrink toward them privately.
Written by Sumit · Last reviewed 12 Oct 2026