How to Compress Images in PowerPoint, Word and Excel

These steps are for current versions of PowerPoint for Microsoft 365. In older versions the tab appears as Format under Picture Tools, but the button and the dialog are the same.

1. Click any picture on a slide. The Picture Format tab appears on the ribbon.
2. On the Picture Format tab, click Compress Pictures in the Adjust group.
3. To compress every picture in the presentation, clear Apply only to this picture. Leave it checked to change only the selected picture.
4. Keep Delete cropped areas of pictures checked unless you might want to undo a crop later (see Delete cropped areas).
5. Under Resolution, choose an option. Web (150 ppi) suits most presentations shown on a screen or projector.
6. Click OK, then save. Use File → Save As with a new name if you want to compare the file sizes.

PowerPoint for Mac has the same feature with a slightly different dialog. It also has a menu command that compresses every picture at once, without selecting one first.

1. To compress all pictures, choose File → Compress Pictures. To compress only some, Shift-click to select them and click Compress Pictures on the Picture Format tab.
2. Choose an option from the Picture Quality menu. The options run from highest to lowest resolution, as in the Windows version.
3. Check Delete cropped areas of pictures if you've finished cropping.
4. Choose Selected pictures only or All pictures in this file, click OK, and save the presentation.

Word and Excel use the same command in the same place: select a picture, open the Picture Format tab and click Compress Pictures. The dialog, the resolution options and the Apply only to this picture checkbox work exactly as they do in PowerPoint, and on a Mac, File → Compress Pictures is there too (some versions of Word call it Reduce File Size).

On Windows there's a second route that compresses every picture as you save. Choose File → Save As, open the full Save As dialog (More options or Browse), click Tools next to the Save button and choose Compress Pictures. It's handy for long Word documents, where finding and selecting a picture first can be fiddly.

Two differences matter in practice. Pictures in Word usually sit inside a text column (6.5 inches wide on a US Letter page with 1-inch margins), so they need far fewer pixels than a picture that fills a slide. And in Excel, screenshots pasted into a workbook add up quickly, so compress them before you email the file.

Office measures resolution in ppi (pixels per inch) at the size the picture is shown on the slide or page, not at its original size. A photo displayed 5 inches wide and compressed at 150 ppi keeps about 750 pixels across, even if it started at 4,000. So set the final size of your pictures before you compress: if you enlarge a picture afterwards, it will look soft.

The table shows what each option means for a picture that fills the width of a standard 16:9 slide (13.33 inches) or the text width of a US Letter page in Word (6.5 inches).

For decks shown on screens and projectors, Web (150 ppi) is the usual sweet spot. Choose Print (220 ppi) for anything that will be printed, and E-mail (96 ppi) only when size matters more than sharpness, since small text inside screenshots can become hard to read. Use default resolution applies whatever is set for the file (see default settings). Options that need more pixels than a picture has may be grayed out, and some versions word the options slightly differently (Email instead of E-mail, for example).

When you crop a picture in Office, the parts you cut off are only hidden. They stay in the file, which is why you can drag the crop handles back out later. Delete cropped areas of pictures throws the hidden parts away when you compress.

The savings can be big on heavily cropped pictures, such as a full-screen screenshot cropped down to one button, or a group photo cropped to a single face. The catch is that you can't un-crop afterwards. The box is usually checked by default, so if you're still working on the layout, clear it for now and run Compress Pictures again once the deck is final.

Besides the Compress Pictures button, every Office file has image settings that apply to all of its pictures: a default resolution that Office applies when you save, and an option to turn compression off. On Windows they're in the same place in PowerPoint, Word and Excel:

1. Go to File → Options → Advanced.
2. Scroll to Image Size and Quality. The drop-down next to the heading chooses which open file the settings apply to; Word also lists All New Documents.
3. Choose a Default resolution, for example 150 ppi for presentations shown on screen.
4. Check Discard editing data to delete the extra data Office keeps for restoring edited pictures. The file gets smaller, but you can no longer reset those pictures to their original state.
5. Make sure Do not compress images in file is unchecked, unless you want every picture kept at full resolution.
6. Click OK and save the file.

Compress Pictures works after the fact, and it only changes resolution. Shrinking images before they go into the file is the better choice in these cases:

You're adding dozens of phone photos. A 12-megapixel photo is typically 3–5MB. Forty of them make a deck well over 100MB that's slow to open, save and sync long before you get around to compressing it.

You work in PowerPoint for the web or Google Slides. Neither has a Compress Pictures command, so the file you insert is what ends up in the presentation.

You need to meet a size limit. An email service or a course portal counts megabytes, not ppi. With FormShrink you can give each image a target size, for example 500KB for photos that fill a slide.

The photos are saved as PNG. Photos exported from design tools, and screenshots of photos, often come as PNG. Lowering the resolution helps, but converting them to JPG usually saves far more. Keep real graphics such as logos, charts and diagrams as PNG so edges stay sharp and transparency survives, and just lower their resolution with Compress Pictures.

To prepare photos for a widescreen deck with FormShrink:

1. Open the image compressor, add up to 10 images and switch to Advanced mode.
2. Set Output Format to JPEG for photos.
3. Turn on Resize Image. The default 1920 × 1080 box with Maintain aspect ratio on fits a picture to a full 16:9 slide, which works out to about 144 ppi. Pictures that are already smaller keep their size.
4. Click Compress Images, then Download All, and add the files to your slides with Insert → Pictures.

Pictures are the usual cause of a bloated file, but not the only one. If compressing didn't help much, check these:

Video and audio. In PowerPoint for Windows, File → Info → Compress Media re-encodes embedded video and audio at a lower quality. The option only appears when the presentation contains media.

Embedded fonts. If Embed fonts in the file is on under File → Options → Save, choose Embed only the characters used in the presentation to keep the font data small.

Unused slide masters. Slides pasted from other decks bring their own masters and layouts, often with large background pictures. Delete the ones you don't use under View → Slide Master.

Find the heavy files. A .pptx, .docx or .xlsx file is really a ZIP archive. Make a copy, change its extension to .zip and open it: the pictures and media are in the ppt/media, word/media or xl/media folder. Sort by size, and the biggest items show you exactly what to fix.