How PDFTuck works
You give PDFTuck a limit. It tries a few quality settings, measures every file it makes, and keeps the best one that fits. Here is each part.
The steps in the app
Select PDF. Android’s own file picker opens. PDFTuck only gets the file you choose and needs no storage permission. It copies the file into its private storage and shows the size and number of pages.
Choose a target or a quality. Tap a preset (200 KB, 500 KB, 1 MB, 2 MB, 5 MB, 10 MB) or type a custom value in KB or MB. Or switch to quality mode: High quality, Balanced or Smallest file.
Compress PDF. A progress screen shows it working. You can cancel at any time.
Check the result. The original size, the new size, how much was saved, the reduction in percent and whether your target was met.
Preview, then save or share. Look through the pages with zoom. Save with Android’s “Save as” dialog, share the file, or open it in your PDF viewer. “Compress another” starts again.
How it finds the best file under your limit
Making a PDF smaller mostly means making its images smaller: fewer pixels and stronger image compression. Stronger settings give smaller files with softer images.
PDFTuck doesn’t guess. It produces a candidate file, measures its real size and compares it with your limit, then adjusts the setting and tries again, narrowing in on the best quality that still fits. It makes at most seven attempts, so it finishes in a predictable time.
The file you get is the best-looking candidate that is at or under your limit. If even the highest-quality setting fits easily, you get that one, which is why the result can be well below the limit.
When the limit can’t be reached
Some PDFs can’t get under some limits without becoming unreadable: many scanned pages under 100 KB, or a long text document that is already compact.
PDFTuck stops at a safe quality floor instead of producing an unreadable page. It then says Best readable result, shows the size it reached, and offers two choices: Use this file, or Try stronger compression, which lowers the floor and warns that readability may drop noticeably.
If neither works, the honest fix is to change the document: remove pages, split it into parts, or rescan it at a lower resolution.
What “KB” and “MB” mean here
PDFTuck uses decimal units: 1 KB is 1,000 bytes and 1 MB is 1,000,000 bytes. Some websites count 1 KB as 1,024 bytes, which makes their limit slightly larger. Typing the website’s number into PDFTuck is therefore safe under either definition.
What changes in the compressed copy
Depending on the document, PDFTuck may turn pages into images to reach your target. When that happens, the text on those pages is no longer searchable or copyable, and links, form fields and annotations are not kept. A digital signature is never valid in a compressed copy, because any change to a signed file breaks the signature.
Your original PDF is never changed. Keep it if you need its text, forms or signature.
Where the work happens
Everything above runs on your phone. The PDF is not uploaded to PDFTuck or to any server, and compressing works in airplane mode. Working copies stay in the app’s private storage. Work files are deleted when a run finishes, and leftover copies older than a day are removed the next time the app starts.
The app does use the internet for Google ads and Google’s consent messages. Those services never receive your PDF.
PDFTuck is in closed testing and is not yet publicly listed on Google Play.
Email to join the test