Drop the PDF and press the button. The tool works in three stages, cheapest first, and stops at the first one that gets the file under 150 KB.
Images are recompressed in place first, so text, links and forms stay exactly as they were. Only when a file still will not fit are the pages rebuilt as images, and even then an invisible text layer keeps the words searchable. A file already under the cap is handed back untouched. If your file is already small enough, you do not need this tool.
Portals asking for 150 KB are usually accepting several documents at once, each capped separately. That matters more than the number, because it means the answer to a file that will not fit is often to send it as two files rather than to compress it harder.
Where the 150 KB limit comes from
- University admission and enrolment portals150 KB per document
- State recruitment boards100 to 150 KB
- Visa appointment and biometric portals150 KB per attachment
- Professional body registrations150 to 200 KB
- Bank and insurance onboarding forms150 KB per page
Where a portal lists several slots each capped at 150 KB, read that as a per-file limit rather than a total. Splitting a four-page document into two two-page files and filling two slots is usually accepted, and it keeps twice the detail.
How the tool hits 150 KB
Add the PDF
Drop it or browse. It is read into browser memory; nothing is uploaded, so a slow connection makes no difference.
Stages one and two: tidy, then the images
Unused objects, thumbnails and stale metadata go first, which costs nothing at all. Then the pictures inside the file are recompressed in place, starting at 200 ppi, while your text, links and form fields are left exactly as they were.
Stage three, only when it is needed
If the images were not where the weight was, the pages are rebuilt as pictures with an invisible text layer behind them, so the words stay searchable. It probes at 150 dpi, works out the resolution that should fit, and will not go below 60 dpi.
Download, and read the result line
It shows the final size and which stage produced it. If none fitted, you still get the smallest attempt, labelled honestly, rather than a file that silently missed the target.
Structure, then the images in place, then the pages as pictures. It stops at the first stage that fits.
Untouched at the first two stages. If the pages do get rebuilt, an invisible text layer keeps them searchable.
The IDs, forms and statements people compress for portals never leave the device.
What fits in 150 KB, and what does not
The honest answer depends on page count and on what is on the pages. Text pages are cheap because a rendered page of black text compresses extremely well as a JPEG. Colour scans and photographs are expensive because every pixel carries information the encoder has to keep. The estimator uses typical figures to show which attempt your file is likely to land on.
When it cannot reach 150 KB
Some documents will not fit legibly, and the tool says so rather than pretending. When the result line reports a miss, three moves usually solve it:
- Split first. Use Split PDF to break the file into parts and compress each. Most portals accept several attachments even when each one is capped at 150 KB.
- Rescan the source. A fresh 150 dpi greyscale scan compresses far better than a colour scan that has already been through one compressor. Every pass costs quality, and the first pass should start from the cleanest source.
- Check the real limit. Portals sometimes state one number and accept another. Read the fine print, or try a slightly larger file before compressing harder than you need to.
Two files at 150 KB beat one at 300
Compression is not linear in a way that helps you. Halving a file's budget costs far more than half its quality, because the encoder has already taken the cheap savings by the time it reaches the tight end of the ladder. Two pages sharing 150 KB get 75 KB of detail apiece. The same two pages split across two files get 150 KB each.
- Check the slot count first. If the form has separate slots for front and back, or for each certificate, the cap is per file and splitting costs you nothing.
- Split on document boundaries. One certificate per file reads better at the other end than an arbitrary page break in the middle of something.
- Name the parts clearly. Whoever opens these is working through a queue, and
degree-certificate-page-1.pdfcosts nothing and saves them guessing.
Where the portal genuinely takes one file and one only, the order of moves is: rescan in greyscale at 150 dpi, crop away the margins the scanner added, and only then compress. Each of those gives the tool a cheaper starting point, so it stops higher up the ladder.
Where people use the 150 KB target
- Degree and transcript pages1 to 2 pages, usually fits
- Passport and visa supporting documents1 page, fits in greyscale
- Experience and relieving letters1 to 3 pages, fits
- Application forms carrying a photograph1 to 2 pages, borderline in colour
Why this runs in your browser
The files people compress for portals are the ones that identify them: passports, ID cards, certificates, bank statements, tax forms. Uploading them to a compression website in order to upload them again to the portal doubles the exposure for no benefit.
The tool is right above
Everything on this page runs in your browser. Scroll up, drop the file, and keep it on your machine.
Common questions
The questions people have with a 150 KB cap in front of them.
01What fits in 150 KB?
A text document of two or three pages, or a single greyscale scan, both comfortably. A colour scan of one page starts around 250 KB, so it has to give up some sharpness to get there.
02Should I split the file instead?
If the portal has more than one upload slot, yes. Two files at 150 KB each carry twice the detail of one file squeezed to the same cap.
03Why is 150 KB such an odd number?
It usually comes from a portal wanting a round figure between the 150 KB and 200 KB conventions, and it has stayed put ever since. There is no technical reason behind it.
04Greyscale or colour?
Greyscale, unless the portal insists otherwise. A greyscale scan at 150 dpi is sharper at this size than a colour scan at any setting, because it has a third of the data to spend.
05What if it will not reach 150 KB?
You get the smallest result the tool could produce without making the page unreadable, and the result line says so. Splitting the file or rescanning in greyscale is usually the fix.
06Will the text still be selectable?
Usually, yes. The first two stages leave the text exactly as it was. If the file only fits by rebuilding the pages as pictures, an invisible text layer goes behind them so the words can still be searched.
07Are my files uploaded anywhere?
No. Rendering and compression run in your browser. The file never leaves the device.
08Is it free?
Free. Every tool, unlimited use, no signup.