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 500 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.
The 500 KB ceiling is a US and European convention. It shows up on school enrolment portals, patient and referral forms, and the small-business web forms whose hosting bills depend on keeping uploads modest. It is roomy enough that most text documents never trouble the ladder, and tight enough that a phone scan of a five-page form needs a few rungs.
Where the 500 KB limit comes from
- US school district enrolment and IEP portals500 KB per upload
- NHS patient portals and hospital referral forms500 KB, sometimes 1 MB
- Small-company careers pages and applicant forms500 KB per file
- Community sites: PTA, HOA, club membership500 KB attachments
- Insurance claim and evidence uploads500 KB to 2 MB
Caps like this are rarely revisited once set. They are written into a portal's upload form at launch, sized for the storage and bandwidth of the day, and outlive both. The practical response is not to argue with the number but to produce a file that clears it while staying readable, which is what the ladder below does.
How the tool hits 500 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 500 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 500 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 500 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.
Text versus scans at half a megabyte
The two kinds of PDF behave so differently at this size that it is worth knowing which one you have before pressing the button. Select a sentence in the file: if words highlight, it is text and will almost certainly fit at the first attempt. If the whole page selects as a block, it is a scan and the ladder is doing real work.
Fit at attempt one
- A twenty-page contract lands around 400 KB with nothing visibly changed
- CVs, letters, forms filled on a computer
- Exports from Word, Docs and LaTeX
- Mixed documents with a few small images
Step down the ladder
- A ten-page black-and-white scan fits comfortably at attempt two or three
- A ten-page colour scan fits with visible softening
- Three or four full-page photos fit with a mild soft-focus effect
- Longer colour scans: split first
Where people use the 500 KB target
- Enrolment forms, medical waivers, transcriptstext, fits at attempt 1
- Referral letters and intake questionnaires1 to 4 pages
- CVs and cover letters for smaller employerstext, fits easily
- Newsletters and minutes for community sitesmixed, usually fits
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 500 KB cap in front of them.
01Why 500 KB?
It is the sweet spot chosen by US school portals, hospital forms and small-business web forms: large enough for any text document, small enough to keep hosting predictable.
02Will text pages stay sharp?
Yes. A text document usually fits at the tidy-up stage, before a single picture is touched, so what you get back is identical to what went in. Keep the original anyway.
03Will the text still be readable?
For text documents, yes, and usually at the first attempt. For colour scans and photo-heavy pages, later attempts soften the image visibly. The result line tells you which attempt produced the file, and the estimator above predicts it.
04Will 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 and copied.
05What if the file cannot get under 500 KB?
You still get the smallest attempt, with the result line stating the final size honestly. Split the file into parts, or rescan the source in greyscale at a lower resolution, and try again.
06My file was already small. Why did it grow?
The tool checks the size first and hands a file that already fits straight back, untouched. If the file is already under the cap, send it as it is.
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.