Compress PDF
Shrink heavy PDFs so they fit email attachments and upload size limits.
☁️ Your file is sent to the CalcLab server (Seoul) and deleted right after it's compressed.
When to compress a PDF
- Email attachments — get a PDF under the usual 10–25 MB attachment limit of Gmail, Outlook and most mail apps.
- Job and college applications — meet upload rules like "max 5 MB" on application portals.
- Still too big? — break it up with Split PDF, or shrink your photos first with Compress Image and then combine them with JPG to PDF.
Frequently asked questions
How much smaller will my PDF get?
PDFs full of photos or scanned pages usually shrink to half their size or less, sometimes to a tenth. Text-only PDFs are already light, so they barely change. If the compressed file would end up bigger than the original, you get the original back.
Which compression level should I pick?
"Medium" keeps screen quality (150 dpi) and is the best all-rounder for email and online forms. "Strong" goes down to 72 dpi for the smallest file, but photos can look soft. "Light" keeps print quality (300 dpi). If you still can't get under an upload limit, try one level stronger.
Will the text get blurry?
No. Text is stored as fonts, not pictures, so it stays sharp. Only photos and scanned pages can lose some detail.
Are my files stored on your server?
PDF compression can't run inside your browser, so your file is sent to the CalcLab server in Seoul. It is deleted right after it's compressed, and we don't keep a copy or look at it.
Is there a limit?
It's free for up to 20 files per person per day, and each PDF can be up to 50 MB.