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How to compress a PDF on iPhone without uploading it

A PDF that's too big to email or upload is usually full of images, most often a scan. You can shrink it right on your iPhone, without sending it to a website. Here are three ways, starting with the free one.

We make PDF Tools Pro (method 3). Methods 1 and 2 use apps that come with your iPhone.

Method 1: Preview (free, built in)

According to Apple's Preview guide for iPhone:

  1. Open the PDF in the Preview app.
  2. Tap next to the file name, then tap Export.
  3. Choose PDF as the format.
  4. Turn on Optimize Images for Screen (reduces image resolution for screen viewing) and/or Save Images as JPEG (smaller embedded images).
  5. Tap save, pick a folder, and rename the copy if you like.

Check the new file's size in the Files app (long-press > Get Info), and open it to make sure the text is still readable.

Method 2: Scan smaller in the first place

If the PDF is a scan you made on your phone, rescanning is often the quickest fix:

  • In the Notes or Files scanner, use Grayscale or Black & White for text documents. Color scans are much bigger.
  • Scan only the pages you need.

Method 3: PDF Tools Pro (on device, no upload)

If you shrink PDFs often, or you're also merging, splitting or scanning, a dedicated app saves steps:

  1. Open PDF Tools Pro and import your PDF into the Library.
  2. Go to Tools and choose the optimize tool for scanned PDFs.
  3. Save the smaller copy, then share it or attach it to an email.

Your document is processed on your iPhone or iPad and isn't uploaded to us. Core tools are free, and every device gets three successful advanced outputs to try. Lifetime Pro unlocks every advanced tool with one purchase, with no subscription.

Should I use a website instead?

Online compressors work, but they require uploading your file to someone else's server. That's fine for a flyer, less so for ID documents, bank statements, medical forms or contracts. For those, use one of the on-device methods above.

Tips for getting under an upload limit

  • Remove pages you don't need first (PDF Tools Pro can extract or split pages).
  • Compress once. Re-compressing an already compressed file rarely helps and can make text blurry.
  • Keep the original until the smaller copy is accepted.

Download on the App Store
Free core tools. Three advanced outputs to try on each device, then Lifetime Pro is a one-time purchase. No subscription.

FAQ

Can I compress a PDF on iPhone for free?
Yes. In Apple's Preview app, export the PDF as a PDF with Optimize Images for Screen or Save Images as JPEG turned on. This creates a smaller copy.
Will compressing a PDF upload it to the internet?
No, not with the methods on this page. Preview and PDF Tools Pro work on your device. Online compressors do require uploading your file.
Why is my scanned PDF so big?
Each scanned page is stored as an image, and color images are large. Scanning in grayscale or black and white, or optimizing the images, makes the file much smaller.
Does PDF Tools Pro need a subscription?
No. Core tools are free, and Lifetime Pro is a one-time purchase that unlocks every advanced tool.
Does PDF Tools Pro need an account?
No. No account is required.
How to Compress a PDF on iPhone (Offline, No Upload)