Your PowerPoint is too big for email. Here is why, and the fix

Most email systems reject attachments over 20 to 25 MB. A twenty slide deck can easily pass that, and it is almost always the pictures.

Where the size comes from

When you drag a photo onto a slide, PowerPoint keeps the whole file. A 12 megapixel phone photo is roughly 4000 pixels wide, but a full screen slide only needs about 1920. You are carrying four times the pixels you can display, times the number of photos.

Cropping does not help either. PowerPoint keeps the hidden parts so you can undo the crop later.

The quick fix

Compress PowerPoint re-encodes the embedded images at a sensible maximum size and quality, leaving text, layouts and animations untouched. The recommended setting caps images at 1600 pixels, which still looks sharp on a projector and typically cuts the file by half or more.

If the deck is going out purely to be read, PowerPoint to PDF is often smaller again, and it guarantees the recipient sees your fonts and layout. Bear in mind that charts and SmartArt are drawn as labelled boxes, and animations do not survive the conversion.

Habits that keep decks small

• Resize photos to about 1920 pixels wide with Compress Image before placing them.
• Avoid pasting screenshots repeatedly. Each paste is a new copy inside the file.
• Delete unused slides rather than hiding them. Hidden slides still carry their images.
• Keep embedded video out of the file and link to it instead.

Checking what is inside

Extract Images from PowerPoint pulls out every picture at its stored size. It is a quick way to see which image is responsible when a deck is unexpectedly large.