My colleague sent me a Google Slides file last week and asked why it looked weird on her phone screen.

I opened it and immediately saw the issue.

She had designed the whole thing in landscape. But she needed it for an Instagram story and a printed flyer. Both vertical. Both portrait orientation.

She had no idea you could even change the slide dimensions in Google Slides.

So I walked her through it over a call and she was done in under a minute. That call is basically this article.

Why You Would Even Need Vertical Slides

Most presentations are horizontal. Widescreen 16 by 9. That is the default everywhere.

But vertical slides make sense in more situations than people realise.

Instagram and TikTok stories are vertical. Printed flyers and posters are usually portrait. Pinterest graphics are vertical. Phone wallpapers are vertical. If you are designing any of these inside Google Slides, you need to flip the orientation.

Google Slides lets you do this through the custom dimensions setting. It is not a button you can just click. You have to go in and manually set the width and height yourself.

Let me show you exactly how.

How to Make Google Slides Vertical on Desktop

This is the method you will use on a laptop or computer and it is the easiest way to do it.

Step 1: Open your Google Slides presentation.

Step 2: Click on File in the top left menu bar.

Step 3: Click on Page Setup from the dropdown menu.

Step 4: A small window will pop up showing your current dimensions. Click the dropdown that says Widescreen 16:9 or Standard or whatever it currently shows.

Step 5: Select Custom from the dropdown options.

Step 6: You will see two boxes showing width and height. By default it is probably set to something like 25.4 cm wide and 14.29 cm tall or 10 inches by 5.63 inches.

Step 7: Swap those numbers. Put the smaller number in the width box and the larger number in the height box.

So if it was 25.4 wide and 14.29 tall, you type 14.29 in the width box and 25.4 in the height box.

Step 8: Click Apply.

Your slides will flip to portrait orientation immediately.

The Exact Numbers to Use for Different Vertical Formats

This is the part most guides skip and it actually matters depending on what you are making.

For Instagram Stories and TikTok, use 19.05 cm wide and 33.87 cm tall. That is a 9 by 16 ratio which fills a vertical phone screen perfectly.

For a standard portrait presentation, use 19.05 cm wide and 25.4 cm tall. That is an A4 proportion and works well for printed documents and flyers.

For a Pinterest graphic, use 10 cm wide and 15 cm tall. That matches the ideal Pinterest image ratio.

For a phone wallpaper, use 9 cm wide and 19.5 cm tall roughly. Adjust slightly depending on the phone model you are targeting.

You enter these values in the custom dimensions box in Step 6 above. Width goes in the first box, height goes in the second.

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What Happens to Your Existing Slides

If you had content already on your slides before changing the orientation, Google Slides will ask you a question when you click Apply.

It will say Do you want to scale existing content or leave it unchanged.

If you click Scale, it will try to resize everything to fit the new dimensions automatically. Results are mixed. Sometimes it looks fine. Sometimes everything gets squeezed and needs fixing.

If you click Don't Scale, your content stays the same size and you will need to manually move and resize things to fit the new vertical layout.

Personally I always choose Don't Scale and fix things manually. The automatic scaling usually creates more problems than it solves.

If you are starting a fresh presentation with no content yet, this question does not come up and you can just set your dimensions before you start designing.

How to Do It on Mobile

The Google Slides mobile app is a bit limited compared to the desktop version.

You actually cannot change the slide dimensions inside the mobile app directly. The Page Setup option is not available on mobile.

What you need to do is open Google Slides in a browser on your phone, not the app. Go to slides.google.com, open your file, and request the desktop version of the site through your browser settings.

Once you are in the desktop view on your phone browser, follow the same steps I described above. File, Page Setup, Custom dimensions, swap the numbers.

It is a bit fiddly on a small screen but it works.

Quick Recap of the Steps

Open Google Slides on desktop.

Click File then Page Setup.

Click the dropdown and select Custom.

Enter your width and height values with height being bigger than width.

Click Apply.

Choose whether to scale existing content or not.

Done.

Final Thoughts

Honestly this takes about thirty seconds once you know where the setting is.

The Page Setup option buried under the File menu is something a lot of people never find on their own because there is no obvious button for it on the main screen.

But now you know exactly where it is and what numbers to enter for whatever format you need.

Go make your vertical slides.

FAQs

Can I make just one slide vertical in Google Slides?

No. Changing the dimensions applies to all slides in the presentation. You cannot have mixed orientations in one file.

What dimensions should I use for an Instagram Story in Google Slides?

Use 19.05 cm wide and 33.87 cm tall. That gives you a proper 9 by 16 vertical ratio for stories.

Will changing orientation mess up my existing content?

It can. Choose Don't Scale when prompted and manually adjust your content to fit the new layout.

Can I change slide dimensions on the Google Slides mobile app?

No. You need to use a desktop browser or request the desktop version of the site on your mobile browser.

What is the standard vertical slide size for printing?

Use 19.05 cm wide and 25.4 cm tall for a standard portrait layout that works well for printed flyers and documents.