Image resolution is often discussed as if pixels, PPI and DPI mean the same thing. They are related, but each describes a different part of the image or output process, and mixing them up leads to files that are too small for print or needlessly heavy for the web.
Pixel dimensions define image data
An image that is 3000 pixels wide contains more horizontal image samples than one that is 900 pixels wide. Pixel dimensions matter when cropping, enlarging or preparing a file for a large display. They do not by themselves guarantee sharpness: focus, motion blur, compression and editing also affect visible detail.
PPI and DPI are not interchangeable
Pixels per inch (PPI) describes how image pixels are mapped to a physical inch in a print layout. Dots per inch (DPI) generally describes printer output dots. A file can be rescaled to a different print size without creating new detail, so a resolution number alone does not make a small image high resolution. For example, a 3000 × 2000 pixel image prints at 10 × 6.7 inches at 300 PPI, or 20 × 13.3 inches at 150 PPI, with exactly the same pixels.
Choose resolution based on output
- Start from the largest reliable original available.
- Calculate the required pixel dimensions for the final print size.
- Do not upsample expecting missing detail to reappear.
- Inspect edges and fine textures after resizing.
Think in terms of final dimensions and viewing distance, not a single resolution number in isolation.
Related reading
Continue with our guide to JPEG, PNG and WebP image formats to pick the right file type once the size is set. For search-related image guidance, see Google Search Central’s guidance on Google Images. For help with product-ready images, explore our product image editing services.
Frequently asked questions
Is 72 PPI enough for web images?
On screens, the PPI tag has little effect. What matters is the pixel width and height, so size web images to the dimensions they will be displayed at.
Can I increase resolution by changing the PPI value?
Changing the PPI number alone does not add detail. It only changes the physical size at which the same pixels would print.
Why does my print look soft even at 300 PPI?
The original may have been out of focus, blurred by motion or heavily compressed. A high PPI value cannot restore detail that was never captured.
