Compress PDF to 100KB

Compress a PDF to 100KB (free, no upload)

Quick answer: add your PDF below. The target is already set to 100KB (0.1 in the Custom size box), so tap Compress to target. The tool turns each page into a JPEG and steps down through up to seven quality passes, from about 144 DPI to about 65 DPI, stopping at the first one under 100KB. One or two pages usually fit: in our test a one-page A4 photo PDF went from 447KB to 65KB, but a three-page photo PDF stopped at 126KB. If yours won't fit, delete pages or split the file first. Nothing is uploaded.

Steps last checked 19 October 2026 by the PDFWhisk team

At a glance

Use this page to compress files quickly with a guided workflow.
Accepted input: .pdf.
Output: downloadable files generated in-browser for supported workflows.

200KB preset 500KB preset

Local processing No server file storage Mobile-friendly

Upload Choose your file
Process Runs locally
Download Save result

Drop your files here

or tap to browse · accepts .pdf

Runs in your browser. No file uploads for supported tools.

Best on desktop for 100MB+ files · mobile recommended under ~100MB.

Runs locally No file uploads No server storage

How local processing works

Your PDF is processed in your browser using local JavaScript libraries.
PDFWhisk does not upload your file to a processing server for supported tools.
Only normal page assets load from the site (HTML/CSS/JS), not your document contents.

Read the privacy proof

Support: contact form (reply in ~24h)

Security & privacy details

How this tool helps

Reduce the file size of your PDF documents right in your browser. Pick a target size (2MB, 5MB, 10MB, 25MB or a custom size from 0.1MB) and PDFWhisk tries up to seven quality passes, from very high to very heavy compression, stopping at the first one under your target. Compression turns each page into an image to shrink the file: text stays readable but won't be selectable or searchable, and links and form fields are not kept. Scanned documents and photo-heavy PDFs shrink the most; a typed, text-only PDF may not shrink at all, and if the result would be bigger the tool keeps your original. Your PDF never leaves your device - all compression happens locally using your browser's processing power. Use it when you need to split large PDFs for portal limits, compress PDFs on iPhone, reduce email attachment size.

Best for

Email attachments Job portals Scanned documents iPhone/Android uploads

How it works

1

Add your PDF

Tap the upload box on this page and choose the PDF. It opens in your browser; nothing is uploaded.
2

Check the target

The Custom size box already says 0.1, which is 100KB. Leave it, or type a slightly higher number if your form allows more (0.2 = 200KB).
3

Compress to target

Tap Compress to target. The tool tries up to seven quality passes and keeps the first one under 100KB.
4

Read the result box

It shows the size before and after and says whether 100KB was reached. If it wasn't, it tells you, and you get the smallest version it could make.
5

Check and download

Zoom in on the preview to check small text, dates and signatures, then download the copy ending -100kb.pdf.

More files today? Free covers 3 tasks a day and files up to 50MB. For unlimited tasks and bigger files, Pro passes start at £1 for 24 hours. One-off payment, no subscription, and your files still stay on your device.

Getting a PDF under 100KB

100KB is one of the smallest upload limits you'll meet. Whether a file fits depends mostly on how many pages it has, so it helps to know what to expect before you start.

What fits under 100KB? Our tests

We ran the tool on three files on 19 October 2026. A one-page A4 photo PDF (447KB) came out at 65KB, using the 72 DPI pass. A three-page text document (295KB) came out at 94KB, also at 72 DPI. A three-page photo PDF (1.4MB) stopped at 126KB even at the lowest pass (about 65 DPI), so it needed splitting. Your results will differ, but the pattern holds: page count matters more than the original file size.

Why a long PDF won't go under 100KB

The compressor turns every page into a JPEG image and lowers the resolution and quality step by step. At the lowest pass each page is still roughly 540 by 760 pixels for A4, which costs tens of kilobytes per page. Below that, text stops being readable, so the tool doesn't go further. Removing pages is the only way to save more.

If it still doesn't fit

First delete any pages the form doesn't ask for, such as blank backs of scans or terms and conditions. Then try again. If every page is needed, split the PDF into parts and upload them separately if the form lets you add more than one file. If the form allows a larger file, 200KB or 500KB keeps noticeably more detail.

Check before you upload

Open the compressed copy and zoom in on reference numbers, dates and signatures. Keep your original: the compressed copy is an image of each page, so it can't be edited or searched, and you may need the full-quality version later.

Before you upload/share

The result box says Target reached: under 100KB.
Small text, dates and signatures are readable when you zoom in.
You still have the original PDF.

Frequently asked questions

Can every PDF be compressed to 100KB?

No. Each page still takes tens of kilobytes even at the lowest pass (about 42KB a page for photos in our test), so one or two pages usually fit and longer or photo-heavy files often don't. In our tests a one-page photo PDF reached 65KB and a three-page text document reached 94KB, but a three-page photo PDF stopped at 126KB.

What if my PDF is still over 100KB?

Remove pages the form doesn't need with Delete Pages, or split the PDF into parts with Split PDF and compress each part. If you are scanning the document yourself, scanning only the pages asked for helps more than any compression setting.

Will the text still be readable at 100KB?

Normal-size typed text usually is, but fine print, stamps and signatures get soft at the lowest passes. Each page becomes an image, so text can't be selected or searched in the compressed copy. Always zoom in on the preview before you upload.

Does 100KB mean 100,000 or 102,400 bytes?

The tool aims for 100,000 bytes, the stricter reading, so the file also passes a form that counts 1KB as 1,024 bytes.

Is my PDF uploaded?

No. The pages are redrawn and saved by your browser on your device. Your original file is not changed.

What to do next

Chain tools together for a complete workflow.

Delete Pages

Remove unwanted pages from a PDF

Split PDF

Extract pages or split a PDF into multiple files

JPG to PDF

Convert images to a PDF document