Compress a presentation PDF full of photos, and export it smaller next time

Compress the deck here

1. Drop the exported PDF on the tool.
2. Pick the preset by where the deck is going:
   • Web (150 dpi) if it will be shown full screen on a projector or a big monitor.
   • Email (110 dpi) if it will be read in a mail app or on a laptop, and must be small.
   • A size target if a portal or a mail server names a number. Type it in KB or MB.
3. Press Compress and read the before and after. The 5 slides that shrank most are listed, so you know which to check.
4. Open the result full screen and look at those slides before you send it.

Real numbers from a 40-slide photo deck

Our test deck: 40 slides at 16:9, each with a full-bleed photo and a title, the photos at 220 ppi (PowerPoint’s default picture resolution, see below). Measured on 11 October 2026:

Target sizes count 1 KB as 1,000 bytes, like the targets themselves. The Email preset took about 13 seconds on a mid-range 2024 laptop; each target took 35 to 50 seconds, because it tries several settings. Print barely helps because the photos are already below 300 dpi; it only re-encodes them a little more tightly. A second Email pass on the 4.4 MB result returned it unchanged: there was nothing left to gain.

The slide titles stayed real, selectable text on every setting; only the photos changed.

What each step costs on a projector or a laptop. A 16:9 slide is 13.33 inches wide in PowerPoint. Shown on a full HD screen or projector, 1920 pixels across, that is about 144 pixels per inch of slide. So:

• Web, 150 dpi, keeps every pixel a full HD screen can show. On a projector, nobody can tell.
• Email, 110 dpi, gives a photo about 1,470 pixels across. Full screen on a full HD display, the screen has slightly more pixels than the photo, so fine detail softens a little; in a window on a laptop, the window has fewer pixels than the photo, so it looks close to the original.
• 72 dpi and below, which a small size target can reach, gives photos 960 pixels across or fewer: enough for a handout read on a phone, soft when projected.

Prevent it at export, next time

The file gets big at export, so that is the cheapest place to fix it.

PowerPoint for Windows. Before exporting, select a picture and use Picture Format, Compress Pictures; untick “Apply only to this picture” so it covers the whole deck, and tick “Delete cropped areas of pictures”. Microsoft’s help gives 220 ppi as Office’s default picture resolution (checked on 11 October 2026). Then File, Export, Create PDF/XPS Document, and set Optimize for to Minimum size instead of Standard; Microsoft describes Minimum size as the choice for an email attachment.

PowerPoint for Mac. Microsoft states that the smaller-file option is not available on macOS (checked on 11 October 2026). What you can do is set PowerPoint, Preferences, General, Print Quality (Paper/PDF) to Medium or Low before exporting, or compress the PDF here afterwards.

Keynote on a Mac. File, Export To, PDF, then the Image Quality pop-up menu. Apple’s guide notes that the higher the image quality, the larger the file (checked on 11 October 2026).

Whichever app you use, keep the full-quality deck as your master and export the small PDF as the travel copy. The guide to creating a PDF covers export settings from other apps.

When to send the source file instead

A PDF is the right format when the deck is read, printed or archived. It is the wrong one when the recipient will present it: animations, transitions and embedded video do not play in a PDF, and nothing in it can be edited. If they will present or change it, send the PowerPoint or Keynote file, compressed with the app’s own picture settings above. If they only need to read it, send the compressed PDF.

When crushing is the wrong answer

Some decks are the photos: a photography portfolio, a property brochure, a product lookbook. For those, the photo quality is the message, and a 72 dpi version undersells the work. Compress with Web at most, and if that is still over the limit, send a link to the full file instead of an attachment. The guide to sending a large PDF covers the options, and PDF too big to email has the attachment limits by provider.

The compressor also does not touch what is not a picture. Embedded fonts, vector charts and slide text stay as they are, so a deck that is big for those reasons barely shrinks, and the result screen says so instead of pretending. And compression is one way: keep the original, because no tool can bring the discarded detail back. For photo PDFs made outside a presentation app, see PDF from photos too big.