Match the page size to your slides
PowerPoint defaults to a 16:9 widescreen slide size (13.33 in × 7.5 in), which is different from the default PDF page size. If the PDF is coming out with slides that look cropped or scaled incorrectly, check the slide size: go to Design > Page Setup. The PDF export honors this setting, so if the PDF's page size doesn't match, scaling occurs. For a presentation-style PDF, set the page size to match your slides exactly. For a print-ready PDF, set it to A4 or US Letter.