Change the size of a PowerPoint slide: 16/9, 4/3, cm, pixels

Creating a “clean” presentation is not only about choosing a good layout: it's also about starting with the good PowerPoint format... and especially know how to modify it correctly when it is not the case.

Because generally, this is often where it gets stuck: you get a deck, you project it, and you discover black bands, a slide that doesn't fill the screen, or elements Coupes at the edges. Sometimes everything even looks “zoomed in” or out of sync after a PDF export.

The cause is almost always the same: the PowerPoint slide format (ratio, orientation, dimensions) is not suitable for use... or has been modified too late.

In our previous blog post, we saw how to choose between 16/9, 4/3, portrayal and scenery according to your situation and use case.

Here, it's time for the tutorial: you will learn how to Change the PowerPoint format, Change the format of a PowerPoint slide (in reality: of the entire presentation), set a PowerPoint format in cm, understand the 16:9 pixel PowerPoint format, and above all have the same format throughout PowerPoint without putting your layout at risk.

By the end of this article, you will also know what to do in the most frequent cases: “Adjust or Maximize?” , “Why do I have black bands?” , “How do I put PowerPoint in portrait/landscape format?” , or “How do I get 1920×1080 without a fuzzy export?”

Let's go!

Understand what you are going to change (to avoid mistakes)

Before clicking on “16/9” or “Custom size”, an explanation is needed to avoid a lot of unpleasant surprises: PowerPoint combines three similar, but different, concepts when it comes to PowerPoint slide format.

For regular readers of our blog: you can go your own way, we already covered this point in the previous article (and we give you the link here).

Format, ratio and dimensions: what is the difference?

• The ratio (or width/height ratio) corresponds to the proportion of your slide: 16/9 or 4/3.
• THEorienting Indicates if your presentation is in landscape format Or in portrait format.
• Les dimensions correspond to the real size of the canvas: the waistline Of the slide in cm (or in inches), via a custom size.

Concretely: you can be in 16/9 (ratio), in landscape (orientation), while adjusting the exact dimensions (for example if you have to respect a template, a specific screen, or a print format).

Can I change the format of a single PowerPoint slide?

No When you go Change the PowerPoint format, PowerPoint applies this setting to The whole presentation. That's why “changing the size of a PowerPoint slide” is a common expression... but technically, you're changing the format of the entire file.

If you need an exception (for example a single portrait slide in the middle of a landscape deck), the simplest approaches are generally:

• separate the content into two files (one in landscape, one in portrait),
• or export the slide separately (PDF/image) according to your mode of distribution.

This point is essential: it explains why a change in format can lead to black bands, elements Coupes, or a “warped” layout if you do it too late.

After this clarification (ratio, orientation, dimensions), let's move on to the essentials: Change the PowerPoint format concretely, without ending up with cut elements or a fragile layout.

Tutorial: change the PowerPoint format (16/9, 4/3, custom)

Change the format of a PowerPoint slide (Windows)

For Change the PowerPoint slide format on Windows (16/9, 4/3 or custom), the manipulation is always done in the same place:

1. Tab Creation
2. Click on Slide size
3. Choose:
   • Standard (4:3) if you want to go 4/3
   • Widescreen (16:9) if you want to switch to 16/9
   • Custom size If you have to change size/dimensions precisely
4. Validate, then PowerPoint generally offers you two options: fit or Maximize (we detail this point just after).

Simple tip: if you are just looking to check the current format of a file, go back to this same menu. This is the most reliable place to confirm if you are in 16/9, 4/3, or in custom format.

Change the PowerPoint slide format (Mac)

On Mac, the logic is the same:

1. Tab Creation/Design
2. Slide size
3. Standard (4:3) / Widescreen (16:9) / Custom size
4. Validate then choose fit or Maximize.

Exact wording may vary slightly depending on the version, but the options remain the same.

Custom size: choose your dimensions (PowerPoint format in cm)

If you need to meet specific requirements, use Custom size :

• Enquire Width and Height (this is where you define the dimensions/size of your slides, including a PowerPoint format in cm).
• Choose the orientation if necessary (landscape/portrait, we'll come back to that in the next part).

This is the preferred method as soon as you have a specific screen, an imposed template, or a print use.

“Adjust” or “Maximize”: what should you choose to change the format without case?

This is THE question that comes up as soon as we Change the format of a PowerPoint.

• fit : PowerPoint reduces content to fit into the new format.
• ✅ Less risk of elements Coupes.
• ⚠️ You may end up with slightly smaller content that needs to be realigned.
• Maximize : PowerPoint expands the content to fill the new format as much as possible.
• ✅ Fills the surface better
• ⚠️ Risk of cropping: texts, logos and visuals close to the edges may be Coupes.

Simple rule:

• Deck already advanced (lots of slides, background images, tables) → start with fit.
• Very light deck/at the beginning of creation → Maximize may work, but control the edges.

Go from 4/3 to 16/9 (and vice versa): “clean” method

If you have to Change PowerPoint format on an existing deck (4/3 ↔ 16/9 conversion), apply this method to limit surprises:

1. Duplicate the file (keep a clean source version).
2. Change the format (4/3 → 16/9 or 16/9 → 4/3).
3. Choose fit (in most cases, this is the safest option).
4. Do a targeted check of the “at risk” slides:
   • Slides with backgrounds (full page images),
   • content close to the edges (logos, legends, titles),
   • Tables and graphics,
   • very dense pages.

To note: If your goal is to have a slide in 1920×1080, don't try to “put PowerPoint into pixels” in this menu.

Here, you mainly regulate the ratio (for example 16/9) and the dimensions (in cm/inches). The 1920×1080 then depends on the export resolution (PNG/JPG/Video), which is detailed in the “pixel dimensions” section.

Once the PowerPoint format Settled (16/9, 4/3 or personalized), there is still the other frequent switch: switch to portrait format Or in landscape format.

Put PowerPoint in portrait/landscape format

Changing the ratio (16/9 or 4/3) is one thing. But in some cases, carousel to read, internal doc, printed material, the real question can quickly become: should we switch to portrait format ?

Put PowerPoint in portrait format

For Put PowerPoint in portrait format, lThe manipulation is done in the same place as the format change:

• Creation/Design tab
• Slide size
• Custom size
• Then, in Orientation, select Portrait (for slides)

From there, PowerPoint applies the portrait format to the whole file: it is therefore a choice of structure (and not a “slide by slide” option).

Put PowerPoint back into landscape format

Same path, choosing Landscape in orientation.

This is the solution if you have recovered a “vertical” deck and you need to Project it or present it by video in a classic setting.

Portrait vs landscape: in which cases does it really work?

To avoid disappointments, remember this:

• Landscape format : the most compatible for projecting and sharing on the screen (the majority of screens are horizontal).
• Portrait format : ideal when the slide is designed as a page to be read (PDF, document, carousel), but riskier when projected: on a 16:9 screen, you can generate empty areas or an impression of “lost” content.

If your goal is to limit the black bands and to maximize the visible space during presentation, the landscape is generally the safest choice.

Between this stage and the future, this is often where our customers block: “We have the right 16/9, but the size does not match”, “We have to respect a template”, “We are asked for exact dimensions”. In other words, learn to adjust the PowerPoint format in cm (or in mm/inches).

Dimensions: choose a PowerPoint format in cm (or mm/inches)

Where can I change the dimensions of a PowerPoint?

To define a precise size, go through Slide size → Custom size : this is where you can change size/dimensions (width + height) of your presentation, beyond simple 16/9 or 4/3.

PowerPoint format in cm: the standard sizes you need to know

If you are looking for reliable references (the most used ones):

• 16:9 Format (Widescreen) : 33.87 cm × 19.05 cm
• 4/3 Size (Standard) : 25.4 cm × 19.05 cm

These values correspond to “classic” PowerPoint sizes. You can then adjust them if you have an imposed template or a distribution constraint.

What dimensions should I choose for A4/A3 (print or PDF to read)?

If your objective is a document (PDF) or a printout:

• A4 portrait : 21 cm x 29.7 cm
• A4 landscape : 29.7 cm × 21 cm
• A3 portrait : 29.7 cm × 42 cm
• A3 landscape : 42 cm x 29.7 cm

In PowerPoint, you can either choose a predefined paper size or enter the dimensions directly by cm in custom size.

Why does PowerPoint show inches (and how do you put inches in centimeters)?

Depending on your configuration, PowerPoint can Show inches instead of cm : This is usually linked to your system's regional settings.

Two simple solutions:

• Adjust system region/language settings (to switch to metrics).
• Or, more direct: enter your values with the unit (e.g. 29.7cm) in the fields: PowerPoint automatically converts.

Maximum size for a PowerPoint slide (and what to do if you exceed it)

PowerPoint imposes a size limit on slides. If you need to produce a very large format (poster, signage), the cleanest method is to working at scale (e.g. 50% or 25%), then export/print to the final size.

At this point, the format is set to the correct frame. But there is still a classic gap between what you set in PowerPoint and what you expect in the end: a clean and usable “pixel” rendering (for the screen, the web or export). This is where many people use the wrong lever.

Dimensions in pixels: 16:9 PowerPoint format in pixels (1080p, 4K...)

This is a point that comes up very often: you are asked for a “PowerPoint in 1920×1080”, you are looking for where to enter pixels... and you can't find anything. It is normal.

In PowerPoint, we mainly set a ratio (16/9, 4/3) and dimensions (often in cm/inches). The “result in pixels” then depends mainly on the export resolution.

The simple rule: pixels depend on export (and DPI)

To obtain a slide in pixels (PNG/JPG), you must remember a rule:

• pixels = inches × DPI

So, at the same ratio, an export at a higher DPI gives a bigger (and sharper) image.

PowerPoint 16/9 format: how many pixels?

Some useful guidelines (put your deck in 16/9, then export with the correct resolution):

• For a typical rendering 720P : 1280×720 px
• For a typical rendering 1080p : 1920 x 1080 px
• For a typical rendering 4K : 3840 × 2160 px

The important idea: The 16/9 comes from the slide format, the 1920×1080 comes from When you export.

How to set PowerPoint to 1920×1080 (the reliable method)

1. Pass your presentation in 16/9 format (Widescreen).
2. Check that your backgrounds and visuals are well adapted (no images that are too small).
3. Export in PNG (rather than in JPG if you want to avoid artifacts).
4. Check the size of the exported file: This is where you can see if you are getting 1920×1080.

Fuzzy export: the 3 most common causes

If your image export is not clear (or “too small”), it is rarely the 16/9 format that is the cause. Most often:

• the source images are already low definition (they pixelate when exported),
• the export resolution is too low,
• or items have been expanded in PowerPoint beyond their original size.

In the next part, we see how have the same format throughout PowerPoint, especially when the file mixes slides that were copied and pasted, imported, or retrieved from other presentations.

How to have the same format all over PowerPoint (and avoid the “patchwork” effect)

Even if PowerPoint imposes a One size fits all For the whole file, sometimes a deck gives the impression of having “several formats”: different margins, titles that do not fit the same, visuals that overflow, slides that seem larger/smaller. In the majority of cases, the problem comes fromAnd from a mixture of sources (copy and paste, import) or provisions (layouts), more than the format itself.

Check the current PowerPoint format (before correcting)

Start by confirming that the file is valid on a single basis:

• Creation/Design → Slide size
• Check if you are in 16/9, 4/3 Or in custom size (dimensions).

If you have to Change PowerPoint format, do it now: correcting the homogeneity before stabilizing the format wastes time.

Why do some slides “not have the same format” when the format is the right one?

The most common causes:

• slides imported with a different theme (fonts, sizes, spacings),
• slides that use a layout different (title, content, section...),
• elements placed “by hand” instead of being in layout areas,
• backgrounds/visuals not cropped for the new ratio (16/9 vs 4/3).

Harmonize copy-pasted slides (without redoing everything)

When you get slides from another deck, the objective is simple: keep a single PowerPoint slide format + a single layout logic.

Good reflex:

• Prioritize function Reuse slides (rather than copy and paste in bulk),
• or, when gluing, choose an option that adapts to the destination theme (to prevent each slide from keeping its “original charter”).

Then, quickly pass over the imported slides: titles, margins, alignments and backgrounds (these are the ones that betray a “mixed” deck the most).

Repair the gaps with the mask (the cleanest method)

If the deck is still inconsistent, go through the Slide mask :

• check that the provisions are consistent (same title/content areas),
• remove/avoid duplicate layouts,
• impose a consistent grid and margins.

This is often the solution when the problem is not “the format”, but the “structure” of the slides.

Troubleshooting: black bands, cut slides, layout deformed after format change

Even following the tutorial for Change the PowerPoint format, there are still cases where the result is not as expected.

Here are the most common problems, with a simple reading: symptom → probable cause → what to do.

Black bands in projection (or screen sharing)

Probable cause: ratio of the presentation different from that of the screen (e.g. deck in 4/3 on a 16:9 screen, or portrait deck projected on a landscape screen).

What to do:

• check if your file is in 16/9 format (Widescreen) or 4/3 (Standard),
• if you present on a modern screen, the 16/9 is generally the most compatible,
• If you are in portrait format, expect empty areas: this is normal, this format is rather made for a document to be read.

Elements cut at the edges after conversion

Probable cause: you have chosen Maximize when changing the format, or elements were too close to the edges before converting.

What to do:

• If possible, go back and try again by choosing fit,
• Otherwise, make a targeted pass on the risky slides: long titles, corner logos, legends, footers.

The layout looks “squashed” or “stretched”

Probable cause: background/background image not adapted to the new ratio (e.g. image planned for 4/3 stretched to 16/9).

What to do:

• replace the background image with a version adapted to the ratio,
• or crop the image in PowerPoint (rather than stretching it),
• Also check for full-page shapes (background rectangles) that can create a sense of distortion.

Slides do not seem “in the same format” in the same file

Probable cause: mixture of layouts, themes, or elements imported from another deck (“patchwork” effect), even if the format is unique.

What to do:

• control the format via Slide size (16/9, 4/3 or customized),
• harmonize via the masque And the provisions,
• reapply a layout + Reinitialize on the slides that deviate.

PDF export: different margins or content that moves

Probable cause: the PDF “reveals” discrepancies that are already present (objects out of area, approximate alignments), or you have elements anchored very close to the edges.

What to do:

• Check the slides with full page backgrounds, tables, footers,
• keep a margin of safety (avoid sticking text/logo at the edge),
• export again and check on a standard PDF reader (not only in PowerPoint).

Export PNG/JPG out of focus (or not at the right pixel size)

Probable cause: export resolution too low, or source images that are too small.

What to do:

• Make sure you are at the right ratio first (often 16/9),
• Use instead PNG if you want sharpness,
• replace low-definition visuals (a pixelated logo will remain so),
• and check the pixel size of the exported file (that's where “1920×1080” comes in).

Now that we've done the tour, here's what to remember before leaving!

Best practices to remember

Fasten the good PowerPoint format Early on, this is what avoids 90% of the problems afterwards (black bands, cut elements, fuzzy export). As soon as a file is started; or as soon as a file is picked up, choose your frame: 16/9, 4/3, portrait/landscape format, or custom format, and only then can you adjust the layout.

Reflexes that avoid unpleasant surprises

• Change the PowerPoint format as soon as possible : the longer you wait, the more “changing the PowerPoint slide format” (i.e. the entire file) creates discrepancies.
• Maintain a margin of safety : avoid texts/logos stuck to the edges (otherwise, it often ends up severed after conversion or projection).
• Unify structure before design : if the deck Comes from multiple sources, the problem often comes from provisions (mask) more than format. It is the key to have the same format throughout PowerPoint visually.
• Pixels = export : for one 16:9 pixel PowerPoint format (e.g. 1920×1080), 16/9 is set in the file, but the size in pixels is mainly about export (and the quality of the visuals).
• Systematic final test : slideshow + export (PDF or PNG) and control of a few “at risk” slides (image backgrounds, tables, dense pages).

Change the PowerPoint slide format is not complicated, but it is a structuring adjustment: it conditions the display (screen/projection), the export (PDF, PNG) and the stability of your layout.

If you only need to remember one logic:

• choose the right one first PowerPoint format (16/9, 4/3, portrait/landscape, or personalized),
• Then set the dimensions (e.g. your PowerPoint format in cm if you have a template),
• and if your deliverable is “in pixels” (e.g. 16:9 pixel PowerPoint format, 1920×1080), think above all exportation.

To go further: if you are still hesitating between 16/9, 4/3, portrait or landscape, find our previous article (link). And if you need to convert an existing deck without lag (backgrounds, tables, multi-source templates), mprez can help you quickly secure the rendering. Contact us hither !

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