Glossary
What are DPI and PPI?
MarkdownWhat they are
An image 3000 pixels wide printed at 300 PPI is 10 inches wide. At 150 PPI the same image prints 20 inches wide but looks less sharp. Many people say DPI when they mean PPI.
Why it matters on a Mac
Changing the PPI value alone does not add detail. For print, aim for about 300 PPI at the final size. For screens, pixel dimensions matter far more than the PPI tag.
How to check or change it on macOS
In Preview, open the image and choose Tools > Adjust Size. Width, height and Resolution are shown there. Untick Resample Image to change the print size without changing the pixels.
How Toolbox handles it
Resize Images changes the pixel dimensions by percentage, longest side or exact size, while keeping proportions if you want. Make PDF Searchable redraws pages as 300 dpi images if you choose Recognise again for pages that already have text.
Frequently asked questions
Is 72 DPI enough?
For screens, yes. For print, 300 PPI at final size is the usual target.
Does a higher DPI make a photo sharper?
Not by itself. Only more pixels add detail.
What is the difference between DPI and PPI?
PPI counts pixels in an image. DPI counts printed dots.
