How do I compress a PDF to under 100 KB?

Compress on Strong, and reduce the document to as few pages as the recipient needs. 100 KB is realistic for a single simple page and unrealistic for a long scan at any acceptable quality. For scanned documents, re-scanning at 150 DPI in grayscale is the single biggest saving available.

Why won't my PDF compress any further?

Either it is born-digital and already small, so there is little image data to remove, or you have reached the file's floor: embedded fonts and the PDF's own structure take up space no setting can reclaim. Removing pages is the lever that still works when compression has stopped.

Does compressing a PDF reduce quality?

Yes. Pages are rebuilt as optimised images, so fine print softens and text stops being selectable or searchable. Layout is preserved. Keep your original for editing and send the compressed copy.

Will zipping the PDF get it under the limit?

Almost never. A PDF's contents are already compressed, so a ZIP of it is usually within a few percent of the same size. It also gives the recipient an extra step, and some upload forms reject archives outright.

Is my PDF uploaded when I compress it here?

No. Compression runs in your browser, which matters when the file is a contract, a passport scan, or a bank statement. You can watch the network tab stay empty while it works.

The form says 100 KB but my file still gets rejected. Why?

If you are emailing rather than uploading, attachments grow in transit because of the way they are encoded, so a file that meets the stated limit on your disk can exceed it on arrival. Getting a PDF under an email attachment limit explains the real number to aim for.

How to Compress a PDF to 100 KB, 200 KB, or 1 MB

By Rehan Shah, Updated September 9, 2026, Published August 28, 2026

Upload forms don't negotiate: under the limit or rejected. Here's what each size target realistically takes, and the honest truth about when a target isn't reachable.

How do I compress a PDF to 100 KB?

Run the file through a PDF compressor on Balanced; if it's still over, try Strong. Not enough? Reduce the page count with Split PDF: sending only the pages that matter beats any setting. For scans, re-scanning at lower DPI shrinks the source itself.

Emailing the file rather than meeting a stated KB target? Email attachment limits work differently, attachments grow in transit, so the size to aim for isn't the number in the limit.

What actually determines PDF size

Three things: how many pages, what's on them, and how they were made. Scanned documents are photographs of paper: big, and very compressible. Born-digital PDFs (exported from Word, invoices, forms) store text as text, so they are already small, with little left to squeeze. A 40-page scan and a 2-page contract are entirely different problems, which is why promises like “compress any PDF to 100 KB” aren't honest.

Why is my PDF so large? ranks the causes in order, scan resolution and colour mode dominate so heavily that everything else is a rounding error.

Which kind of PDF do you have?

Before touching a setting, find out which problem you are solving, because the two behave completely differently under compression. Open the file and try to drag-select a line of text. If the cursor highlights the words, the PDF is born-digital and the text is stored as text. If it draws a rectangle across everything, you have a scan: a photograph of a page, with no text in it at all.

A scan is mostly image data, which is exactly what a compressor is good at, so large reductions are normal. A born-digital PDF is already close to as small as its contents allow, and squeezing it may save very little: occasionally nothing. That is not the tool failing; there is simply not much there to remove.

Why is my PDF so large? goes further into diagnosing the cause, including the case where compressing a text-only PDF makes it bigger rather than smaller.

Target by target

Target	Realistic for	How
Under 1 MB	Most documents up to ~20 scanned pages	Balanced usually does it; Strong for image-heavy files
Under 500 KB	Short scans (1-5 pages), most digital PDFs	Strong; check fine print stays readable
Under 200 KB	1-2 scanned pages, small digital PDFs	Strong + trim to only the needed pages
Under 100 KB	Single pages, simple digital documents	Strong + single page; scans may need lower-DPI re-scan

The ladder, in order

Compress on Balanced: the honest before/after readout shows exactly what you gained.
Step up to Strong, biggest squeeze; fine print softens, layout stays intact.
Cut pages, extract just the pages the recipient needs; pages you don't send weigh nothing.
Fix the source, for scans: re-scan at 150 DPI grayscale instead of 600 DPI color; the file starts several times smaller.

Why your PDF won't go below a certain size

Every PDF has a floor, and once you reach it more compression stops helping. Some of the file is structure the format requires: the page tree, the cross-reference table, colour profiles, and any embedded fonts, which can run to tens of kilobytes on their own regardless of how little text uses them.

The rest of the floor is set by how much page you are asking to fit. A hard target is really a budget divided by page count. Around 100 KB, a single simple page is comfortable, two are tight, and twenty are not going to happen at any quality you would be willing to send: the compressor would have to reduce each page to a smear.

This is why removing pages beats every setting. Cutting a 20-page scan to the 3 pages the recipient actually needs multiplies your per-page budget by about seven, and it does it without degrading anything that remains.

What you trade away

Browser-side PDF compression rebuilds pages as optimized images: dramatic savings on scans, but text in the compressed copy is no longer selectable or searchable, and form fields are flattened. Keep your original for editing; send the compressed copy. If you will need the wording later, run PDF to Text on the original first, while the text layer is still there. And because our compressor runs entirely in your browser, a confidential contract never leaves your device on the way to getting smaller.

Common questions

How do I compress a PDF to under 100 KB?: Compress on Strong, and reduce the document to as few pages as the recipient needs. 100 KB is realistic for a single simple page and unrealistic for a long scan at any acceptable quality. For scanned documents, re-scanning at 150 DPI in grayscale is the single biggest saving available.
Why won't my PDF compress any further?: Either it is born-digital and already small, so there is little image data to remove, or you have reached the file's floor: embedded fonts and the PDF's own structure take up space no setting can reclaim. Removing pages is the lever that still works when compression has stopped.
Does compressing a PDF reduce quality?: Yes. Pages are rebuilt as optimised images, so fine print softens and text stops being selectable or searchable. Layout is preserved. Keep your original for editing and send the compressed copy.
Will zipping the PDF get it under the limit?: Almost never. A PDF's contents are already compressed, so a ZIP of it is usually within a few percent of the same size. It also gives the recipient an extra step, and some upload forms reject archives outright.
Is my PDF uploaded when I compress it here?: No. Compression runs in your browser, which matters when the file is a contract, a passport scan, or a bank statement. You can watch the network tab stay empty while it works.
The form says 100 KB but my file still gets rejected. Why?: If you are emailing rather than uploading, attachments grow in transit because of the way they are encoded, so a file that meets the stated limit on your disk can exceed it on arrival. Getting a PDF under an email attachment limit explains the real number to aim for.

Try it yourself

These live under PDF tools, alongside the rest of the pdf size guides on the guides page.