Powerpoint slide size changes from my setting

Question

Powerpoint slide size changes from my setting

Jim Race 0

I've been using a custom slide size of 800 pixel for social media purposes. Powerpoint has suddenly started converting my slide sizes from 800px to 1833px. I've tried resetting the slide size from scratch using pixels and cm (21.167cm), but the forced adjustment still happens. Has something changed with Ppt?

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2 answers

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Answer 1

Sorry, but PowerPoint, Google Slides and Apple Keynote all store measurements as physical measurement, not as pixels. There is a widespread misunderstanding that presentations should be designed like web pages, using pixel measurements, but this will lead to unexpected results.

PowerPoint will convert from pixels to inches or centimeters using the current resolution of your computer. Different resolution settings will result in different conversions and different final sizes for the deck.

You haven't told us how you are using PowerPoint in social media. You might be uploading your file to Onedrive, then using an embed link in a post. or you might be converting slides to graphics, then posting those. If you can post the method you are using, I can give you steps to get more reliable results.

Answer 2

Set the slide by its aspect ratio, then export it at exactly 800 pixels rather than trying to make the PowerPoint canvas itself 800 pixels wide.

PowerPoint slides are dimension-based, not pixel-native. Although the Custom Slide Size dialog accepts px, PowerPoint converts that value to the operating system’s measurement units, and the documented maximum is 720 px / 56 inches / 142.24 cm per dimension. Consequently, 800 px is not a supported slide dimension.^1^

The reported 1833 px is consistent with an 8.333-inch slide—21.167 cm—being rendered at approximately 220 pixels per inch:

21.167 cm ÷ 2.54 × 220 ≈ 1833 px

That indicates a conversion during image output, not necessarily a change to the presentation’s physical slide size. Microsoft’s current Windows issues list does not identify an acknowledged 800-to-1833-pixel regression.^2^

Export at exactly 800 pixels

Since resetting the slide in both pixels and centimeters has not changed the result, leave it at a convenient physical size with the required aspect ratio. For a square social-media image, equal width and height are sufficient.

PowerPoint’s VBA Presentation.Export method accepts the output width and height explicitly in pixels.^3^

Press Alt+F11 in PowerPoint.
Select Insert > Module.
Paste this macro:

Sub ExportSlides800Square()
    Dim outputFolder As String

    outputFolder = Environ$("USERPROFILE") & "\Desktop\PPT-800px"
    If Dir(outputFolder, vbDirectory) = "" Then MkDir outputFolder

    ActivePresentation.Export _
        Path:=outputFolder, _
        FilterName:="PNG", _
        ScaleWidth:=800, _
        ScaleHeight:=800
End Sub

Press F5 while the cursor is inside the macro.
Open the PPT-800px folder on the desktop. Each slide should be an 800 × 800 PNG.

For a non-square design, replace ScaleHeight:=800 with the required height. For example, a 4:5 social-media image would use width 800 and height 1000. PowerPoint documents ScaleWidth and ScaleHeight as the pixel dimensions of each exported slide.^3^

If the ordinary export still needs investigation

Check File > Account > About PowerPoint and record the full version and build. If the 1833-pixel behavior began immediately after an Office update, report it through Help > Feedback > Report a problem, including:

PowerPoint version and build
Slide dimensions shown under Design > Slide Size > Custom Slide Size
Export method used
Expected output: 800 px
Actual output: 1833 px

Avoid changing image-compression settings as a slide-size fix. High fidelity and related options control pictures stored inside the presentation; they do not provide a reliable exact-pixel dimension for the exported slide.

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