Shrink a PDF on iPhone and iPad: Preview, Files and the result

First check your device and system version

Apple describes PDF export in Preview in separate user guides for iPhone and iPad and for each system version. The basic route is similar everywhere, but the PDF options offered are not: what the iPhone guide shows for iOS 27 does not automatically apply to the iPad or to older iOS versions. So check which version is running on your device and follow the matching section.

Export a PDF in Preview on iPhone

Yes, if your iPhone runs one of the versions described, you can export a new PDF copy in the Preview app without any additional app. Whether it gets smaller depends on the options offered and on the content of the PDF. When exporting, make sure to keep PDF as the format: if you choose an image format instead, you get images and no longer a PDF document.

iPhone with iOS 27

1. Open the Preview app and, in it, the PDF.
2. Tap the action menu next to the file name and choose “Export”.
3. Choose PDF as the format.
4. Set the PDF options you need and confirm them.
5. Choose a location, enter your own name under “Save As”, and tap “Save”.

According to the Apple user guide for iOS 27, PDF export offers four options with very different effects:

• Optimize images for screen display: lowers the resolution of the images in the PDF. This can make the file smaller, but makes fine details and small text in scans coarser.
• Save images as JPEG: stores the images in JPEG format. How size and image quality change depends on the source material.
• Embed text using text recognition: places recognized text in scanned pages so you can search them. This option is for searching and does not, on its own, promise a smaller file.
• Linearized PDF: prepares the file so that the first pages appear faster when it is loaded from the web. This option, too, aims at faster loading rather than a smaller file.

The size slider mentioned in the same user guide belongs to exporting as HEIC or JPEG, not to PDF.

iPhone with iOS 26

1. Open the PDF in the Preview app.
2. Tap the action menu next to the file name and then “Export”.
3. Choose PDF as the format.
4. Use the adjustments shown to you next and save the new file.

The Apple user guide for iOS 26 mentions an optional size adjustment, but does not say which format it appears for. So rely on the options your device actually shows during PDF export.

In both versions, save the export under its own name, for example with the suffix “klein” (“small”), so that the original is kept. Then compare the size of the new file with the original: what changes depends on the content, and sometimes the copy is barely smaller or not smaller at all. There is no fixed saving.

Does this work on the iPad too?

Yes. For iPadOS 26 and iPadOS 27, Apple describes the same basic route as on the iPhone:

1. Open the PDF in the Preview app.
2. Tap the action menu next to the file name and choose “Export”.
3. Choose PDF as the format.
4. Use the optional adjustments shown and save the copy under a new name.

The four PDF options from the iPhone user guide for iOS 27 do not appear in the iPad user guides. So don’t automatically expect them on the iPad; work with what your device offers when exporting. You’ll find the steps in the user guide for iPadOS 26 and the user guide for iPadOS 27.

Why “Compress” in Files creates a ZIP

In the Files app, there is a “Compress” action for selected files. It does not shrink a PDF; according to Apple, it packs files into a ZIP archive: a single file keeps its name and gets the .zip extension, while multiple files end up together in Archive.zip. When you open the archive, its contents are unpacked again.

If a portal or recipient requires a PDF, the ZIP file won’t help you. It is a container, not a PDF, and packing it changes neither the images nor the structure of the PDF inside. In this case, you need a real PDF copy from Preview or from the browser.

Alternative: shrink the PDF in your browser and save it in Files

If Preview is missing on your device, its options aren’t enough for you, or you want to set a target size, you can shrink the PDF in your browser. The document contents are processed in your browser and not sent to a processing service. However, Safari loads the page and its program components from the internet, so plan for a connection so that the tool loads completely. There is no guarantee that it can be reopened later without a network.

Select and compress the PDF

1. Open the page in Safari, tap “Choose PDF” and select your file.
2. Choose a method: Balanced, Smaller file or Lossless optimization.
3. If needed, set an upper limit via “Set target size”.
4. Tap “Compress PDF”.
5. As soon as the result is ready, tap the link with the file name and “download”.

Lossless optimization tidies up the structure of the PDF and can pack data streams more efficiently, including those of images; image content and image quality are preserved. Balanced and Smaller file can re-save suitable images as JPEG and thereby change image data. None of the methods changes pixel dimensions, removes pages or adds text recognition. Every attempt starts from the original; if the tool finds no smaller valid version, you get an unchanged copy. A target size is an upper limit that the result may reach at most, but not a guarantee. The guide to compression and quality explains exactly what the methods change.

You can select PDFs up to 50 MiB. The compressor rejects encrypted, digitally signed or certified PDFs, as well as files whose structure it cannot read; background information is in the guide to signatures and forms. Very image-heavy documents need more working memory during processing than their file size. If the process aborts on your device, a smaller source file or a computer may help.

Save the result in Files

What happens after you tap the download link can look different depending on your device and settings. In any case, save the generated PDF and not the tool’s web page. Apple describes the following routes for iOS 26 and iPadOS 26; menus may differ in other versions.

• The PDF opens in Safari on iPhone: depending on the tab layout, you tap Share directly or first More and then Share. Choose “Save to Files”, enter a name and tap “Save” (Apple instructions for iOS 26).
• The PDF opens in Safari on iPad: via Share and More you get to “Save to Files”, enter a name and tap “Save” (Apple instructions for iPadOS 26).
• Safari downloads the file directly: you’ll find it in the Files app under Browse → Downloads. If it isn’t there, the downloads indicator in Safari shows the status and offers quick access (Find downloaded files on iPhone).

Where the download ends up

On an iPhone with iOS 26, you set the location under Settings → Apps → Safari → Downloads. You can choose iCloud Drive, a location on the iPhone itself or another folder (Safari settings for iOS 26). If the folder is in iCloud Drive, the file is also available on your other devices using the same Apple Account. Processing in the browser and saving in the cloud are therefore two separate steps: if the file should stay on the device only, choose a location on the iPhone.

Then open the new file from the Files app, not just the preview on the web page. Only the saved file shows that the download arrived completely.

Why document scans on the iPhone get so large

A scan contains the pages as images, one or more per page, and sometimes recognized text as well. How much storage the images need depends mainly on three things: the pixel count, the encoding of the images and the number of pages. Multi-page color scans can therefore quickly become large without anything being set incorrectly on the device.

For such files there are two different levers. On iOS 27, PDF export in Preview can lower the image resolution for screen display and thereby reduce the pixel count. Our browser tool leaves pixel dimensions unchanged, but in the Balanced and Smaller file methods it can re-encode suitable images as JPEG. Which route does more for your scan depends on the material, so it’s worth comparing both results. Text recognition serves a different purpose: it makes a scan searchable but does not promise a smaller file. Our tool does not add text recognition.

The guide Understanding scan file size explains how to choose resolution and color sensibly when scanning. If you have individual photos instead of a PDF, you can prepare JPG/PNG as a PDF; the tool accepts JPG and PNG images.

Check the copy before you pass it on

Whether you used Preview or the browser: open the saved file and go through it briefly.

• Name and extension: does the new file end in .pdf and have a different name from the original?
• Size: is it below the recipient’s limit? You can use the Check upload limits calculator to work through whether they mean MB or MiB and whether individual or total sizes count.
• Pages: are all the required pages there and in the right order?
• Legibility: zoom in on areas with small text, stamps, tables and signatures.
• Functions: an export in Preview says nothing about whether fillable form fields, digital signatures or archiving standards are preserved. If you need them, check them specifically.

Keep the original until the recipient has accepted the file; only they decide whether they accept the reduced PDF. If the file is still too large, or only small enough at poor quality, you’ll find the right next steps in the guide PDF won’t get smaller.