Summary

A 90 MB deck that will not attach to an email is almost always carrying full-resolution photos, an embedded video, and a font library nobody asked for. This article shows you how to find what is inflating the file and remove it — compressing pictures and media, dropping embedded fonts, converting legacy formats, and clearing unused slide masters — without wrecking the quality of what stays on screen.

Symptoms

• Outlook rejects the attachment with The file is too large or bounces the message back with a size error.
• The presentation takes 30 seconds or more to open, save, or scroll.
• The .pptx file is tens or hundreds of megabytes despite a modest slide count.
• Saving over a network drive or to OneDrive stalls or times out.
• PowerPoint freezes when you jump between slides that contain images or video.

In this guide

• 1. Check the Size and Save a Copy First
• 2. Find Out What Is Actually Making the File Big
• 3. Compress the Pictures
• 4. Compress Embedded Video and Audio
• 5. Turn Off Embedded Fonts
• 6. Convert a Legacy .ppt File to .pptx
• 7. Remove Unused Slide Masters and Layouts
• 8. Send a Link When the Deck Needs to Stay Large

Before You Start

• Microsoft PowerPoint, desktop version. Compress Pictures and Compress Media are not available in PowerPoint for the web.
• Write access to the presentation and enough disk space to keep a second copy.
• No admin rights required.

Instructions

1. Check the Size and Save a Copy First

Every technique below permanently discards data. Establish a baseline and protect the original before you start.

1. In File Explorer, navigate to the presentation, right-click it, and select Properties. The General tab shows the current size in MB. Write it down.
2. Open the presentation in PowerPoint.
3. Click File > Save a Copy (or Save As on older builds).
4. Add -original to the filename and click Save. This copy is your undo button.
5. Close that copy and reopen the working file. Everything from here happens on the working file.

Note: Compression is reversible with Ctrl + Z only while the file stays open. The moment you save, the discarded pixels are gone. This is the single reason to keep the original copy.

2. Find Out What Is Actually Making the File Big

Guessing wastes time. A .pptx file is a ZIP archive, so you can open it and see exactly what is inside.

1. In File Explorer, right-click the presentation and select Copy, then right-click empty space and select Paste. Work on the copy.
2. Right-click the copy, select Rename, and change the extension from .pptx to .zip. Click Yes when Windows warns that the file may become unusable.
3. Double-click the .zip file to browse it, then open the ppt folder and the media folder inside it.
4. Click the View tab in File Explorer, select Details, then click the Size column heading to sort largest first.
5. Read the list. Files named image1.png, image7.jpeg, and so on are your pictures; media1.mp4 is embedded video. Anything above 2 MB is a target.
6. Close the window and delete the .zip copy. You have what you need — this step never modifies the real presentation.

Tip: If the media folder is small and the file is still huge, the weight is in embedded fonts or leftover slide masters. Skip to step 5 and step 7.

3. Compress the Pictures

This is the biggest win in almost every deck. A single phone photo can carry 8 MB of pixels onto a slide that displays a fraction of them.

1. Click any picture on any slide. A Picture Format tab appears at the end of the ribbon — it is labelled Format in PowerPoint 2019 and earlier.
2. Click Picture Format, then click Compress Pictures in the Adjust group at the far left. The button shows a small image with arrows pointing inward.
3. The Compress Pictures dialog opens. Under Compression options, clear the checkbox for Apply only to this picture. Clearing it applies the change to every image in the presentation in one pass.
4. Check Delete cropped areas of pictures. PowerPoint stores the whole original image behind every crop, so this alone often removes a third of the file.
5. Under Resolution, choose based on where the deck ends up:
   • HD (330 ppi) — printing at high quality, or images that get zoomed into.
   • Print (220 ppi) — a deck that will be printed as handouts.
   • Web (150 ppi) — the right choice for anything presented on a screen or projector, and the best size-to-quality trade.
   • E-mail (96 ppi) — smallest possible file. Fine for text-heavy slides, visibly soft on photographs.
6. Click OK. The dialog closes with no progress bar — the work is already done.
7. Press Ctrl + S to save, then check the new file size in Properties.

Verification: Click through every slide containing a photo before you save. Compression artefacts show up first on faces, logos, and fine text inside screenshots. If anything looks rough, press Ctrl + Z immediately and repeat at a higher resolution.

To stop the problem coming back, tell PowerPoint to compress on insert: click File > Options > Advanced, scroll to Image Size and Quality, check Discard editing data, confirm Do not compress images in file is unchecked, and set Default resolution to 150 ppi. These settings apply to the current presentation only, so repeat them on your template.

4. Compress Embedded Video and Audio

One embedded video routinely outweighs every slide in the deck combined.

1. Click File > Info.
2. Look for Compress Media in the centre column. This button appears only when the presentation contains embedded video or audio — if it is absent, your media is linked rather than embedded, and it adds nothing to the file size.
3. Click Compress Media and choose a quality:
   • Full HD (1080p) — keeps quality high, saves the least.
   • HD (720p) — the balanced choice for a projected presentation.
   • Standard (480p) — smallest file, fine for screen-share and web playback.
4. A Compress Media progress window opens and lists each media file as it is processed. A deck with several videos takes a few minutes.
5. When the window shows the space saved for each item, click Close.
6. Play each video once to confirm it still runs, then press Ctrl + S.

Tip: If the video lives on SharePoint, Stream, or YouTube, remove the embedded copy and insert a link instead: Insert > Video > Online Video, paste the address, and click Insert. The deck keeps the video and loses the megabytes, provided the room has an internet connection.

5. Turn Off Embedded Fonts

Font embedding guarantees your deck looks right on someone else's machine. It also adds several megabytes per font family, and it is switched on in a lot of corporate templates without anyone knowing.

1. Click File > Options.
2. Select Save in the left sidebar of the PowerPoint Options dialog.
3. Scroll to the section headed Preserve fidelity when sharing this presentation at the bottom.
4. Look at Embed fonts in the file. If it is checked, it is contributing to your file size.
5. Choose one:
   • Clear the checkbox entirely. Smallest file. Use this when the deck uses standard fonts such as Calibri, Aptos, or Arial, or when you will be presenting from your own laptop.
   • Leave it checked and select Embed only the characters used in the presentation (best for reducing file size). Use this when the deck uses a custom brand font and someone else will open it.
   • Avoid Embed all characters (best for editing by other people) unless a colleague genuinely needs to edit the deck in your brand font. This option is the expensive one.
6. Click OK, then press Ctrl + S. The saving appears on this save, not before.

Note: This setting is stored per presentation, not per application. Turning it off in one deck does not affect the next one you open.

6. Convert a Legacy .ppt File to .pptx

The old .ppt format from PowerPoint 2003 and earlier stores everything uncompressed. Converting typically cuts the size in half before you change anything else.

1. Look at the title bar. A legacy file shows Compatibility Mode beside the filename.
2. Click File > Info.
3. Click Convert in the centre column.
4. Click OK when PowerPoint explains that the presentation will be upgraded to the current format.
5. Press Ctrl + S. The file is now .pptx.
6. If Convert does not appear, use File > Save a Copy, set Save as type to PowerPoint Presentation (*.pptx), and click Save.

Note: Converting also unlocks features that are disabled in Compatibility Mode, including Compress Media and modern transitions. Keep the original .ppt if anyone in the chain is still running Office 2003.

7. Remove Unused Slide Masters and Layouts

Decks assembled from several templates accumulate slide masters, each carrying its own background images and logos even when no slide uses it.

1. Click View > Slide Master in the Master Views group. The left pane changes to show each master as a large thumbnail with its layouts indented beneath it.
2. Hover over each master thumbnail. The tooltip states how many slides use it — a master reading Used by no slides is dead weight.
3. Right-click an unused master and select Delete Master.
4. Right-click any unused layout beneath a master you are keeping and select Delete Layout. Layouts in use are greyed out and cannot be deleted, so there is no risk of breaking a slide.
5. Click Close Master View on the ribbon to return to normal editing.
6. Press Ctrl + S and recheck the file size.

Verification: Click through the full deck after deleting masters. Any slide that loses its background or logo was using a master you removed — press Ctrl + Z to bring it back.

Note: Slide Master view is also where the deck's fonts, colours, and logo are set for every slide at once. If you are unsure which master a slide depends on before deleting it, How to Use the Slide Master in PowerPoint explains how the masters and layouts relate.

8. Send a Link When the Deck Needs to Stay Large

Some decks genuinely need their video and high-resolution imagery. Stop fighting the attachment limit and change how you send it.

1. Save the presentation to OneDrive — click File > Save a Copy, select your OneDrive location, and click Save.
2. In Outlook, create a New Email.
3. Click Attach File, find the presentation under Recent Items, and select it.
4. Choose Share link when Outlook offers the choice. The attachment shows a cloud icon instead of a file icon, confirming a link was sent rather than a copy.
5. Click the dropdown arrow beside the attached link and set the permission — Anyone with the link can view for external recipients, or Specific people for anything confidential.
6. Send the email. The recipient opens the current version, at full quality, with no size limit involved.

Full details, including sharing with people outside your organisation, are in How to Send Large Files Without Email Attachments.

Troubleshooting

WARNING

Compress Pictures and Delete cropped areas of pictures cannot be undone once the file is saved. The discarded pixels are removed from the file, not hidden. Always work on a copy and keep the original at full resolution — you will need it the day someone asks for a printed version.

Symptom / Error	Potential Cause	Solution
File size barely changed after compressing pictures	Apply only to this picture was left checked	Repeat step 3 and clear that checkbox so the compression covers every image, then save.
Compress Media is missing from File > Info	No embedded media, or file is in Compatibility Mode	Linked video adds no size. If the title bar reads Compatibility Mode, convert the file first (step 6).
Images look blurry or blocky after saving	Resolution set too low	Reopen your -original copy from step 1 and repeat step 3 at Print (220 ppi) or HD (330 ppi).
File still large with no big images or video	Embedded fonts or unused slide masters	Turn off font embedding (step 5) and delete unused masters (step 7).
Attachment rejected at 22 MB despite the 25 MB limit	Encoding adds around 30 percent in transit	Send a OneDrive link instead (step 8), or compress to Web (150 ppi) to get well under 15 MB.
Fonts change on the recipient's machine after compressing	Font embedding switched off	Re-enable Embed fonts in the file with Embed only the characters used in the presentation, or export a PDF for viewing only.
PowerPoint freezes during Compress Media	Long or high-bitrate video	Leave it running — a 4K video takes several minutes. If it stalls beyond 15 minutes, close without saving and replace the video with an online link instead.

Related Articles

• How to Send Large Files Without Email Attachments
• How to Manage Email Attachments and Send Large Files in Outlook
• How to Fix PowerPoint Not Opening or Crashing
• How to Create an Effective PowerPoint Presentation
• How to Add Speaker Notes in PowerPoint
• How to Use the Slide Master in PowerPoint
• How to Export a PowerPoint Presentation as a Video
• How to Save or Print Any Document as a PDF

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