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How to compress a PDF on iPhone and iPad

Compress PDF in Unlock my PDF shrinks a PDF that's too big for an email or an upload form. You pick how strong the compression is, see the estimated size before you start, and the file never leaves your device.

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Free · once a day iPhone and iPad · iOS 16+ About 20 seconds
Compressed: from 15.8 MB to 2.7 MB, 83% saved, with Share, Save to Files and Open

Step by step

  1. Step 1

    Open Compress PDF

    In the Tools tab, tap Compress PDF. Then tap Tap to choose and pick the PDF from Files, or scan a document straight into a PDF.

  2. Step 2

    Choose the compression level

    Light keeps almost all the quality, Medium is a good balance, and Strong gives the smallest file. Under each level you see an estimate of the new size.

    The Compress PDF options with Light, Medium and Strong and the estimated size for each
  3. Step 3

    Slide to compress

    Drag Slide to compress. The app writes a new, smaller copy and leaves the original as it is.

  4. Step 4

    Check the result and send it

    Compressed shows the size before and after and how much you saved. Tap Share to attach it to an email or Save to Files to keep it.

    Compressed: from 15.8 MB to 2.7 MB, 83% saved, with Share, Save to Files and Open

Good to know

Which level to choose

Start with Medium. Use Strong only when the file must be really small: it turns pages into images, so the text can no longer be selected or searched.

Why some PDFs barely shrink

PDFs with photos and scans shrink a lot. A PDF made only of text is already small, and may not get smaller at all: in that case the app tells you, saves nothing and doesn't count your free use.

Under an exact size for email and upload forms

Many email services stop attachments at 20–25 MB, and online forms often accept 1, 2 or 5 MB. With Premium, turn on Under an exact size and choose 1, 2, 5 or 10 MB: the app picks the level for you.

Older iPhones

Light and Medium need iOS 16.4 or later. On iOS 16.0–16.3 you can use Strong.

Free once a day after a short video. Unlimited with Premium. The PDF is processed on your device. Unlock my PDF has no servers that receive your files.

Questions

Does compressing reduce the quality?

A little with Light, more with the stronger levels. Text stays sharp with Light and Medium; Strong turns the pages into images.

Can I compress a protected PDF?

Yes. The app asks for the password you know, and the smaller copy stays protected with the same password. With Premium you can remove the password from the result.

Is Compress PDF free?

Yes, once a day after a short video, and if no video is available you can use it anyway. Premium makes it unlimited and adds compression under an exact size.

Is the PDF uploaded to a server?

No. The compression runs on your iPhone or iPad.

How to merge PDF files on iPhone and iPad Merge PDF in Unlock my PDF joins two or more PDFs into a single file: add them, drag them into order and slide. How to convert photos to a PDF on iPhone and iPad Photos to PDF in Unlock my PDF turns the photos you pick into one PDF, one photo per page. How to password protect a PDF on iPhone and iPad With Unlock my PDF you choose a PDF, type a password twice and slide: the copy is encrypted and asks for that password every time it's opened, on any device.

Do it now on your iPhone or iPad

Unlock my PDF is free to download. Your PDFs are processed on your device: no uploads, no account.

Download on the App Store

Updated October 2026 · app 2.0