What is the difference between DPI and PPI?
DPI stands for dots per inch and refers to the number of ink droplets in a square inch of a printed design. The higher the number of dots per inch, the higher the quality of the print.
PPI stands for pixels per inch and refers to the number of pixels within one square inch on a screen.
Confusingly, many people (and even some computer programs!) use these terms interchangeably.
Do my images really need to be 300 DPI/PPI?
On it's own, DPI/PPI are not good indicators of an image being good or bad quality. Instead, the most important factor in evaluating the quality of a digital image is the number of pixels and physical dimensions of your image.
If you want to use the image for printing, then you need to decide how large you want your printed image to be.
This image of a forest is 4096 pixels x 4096 pixels - below you can see that the larger print size of the image, the lower the PPI.
| Number of pixels | 4096 px x 4096 px | 4096 px x 4096 px | 4096 px x 4096 px |
| Print size | 13.65" x 13.65" | 42.67" x 42.67" | 56.89" x 56.89" |
| Pixels per inch (PPI) | 300 | 96 | 72 |
How do I know if my image is good enough for print?
The gold standard for image quality is that your image should be at least 300 PPI when scaled to the physical dimensions that you want for your printed image.
To calculate this all you need to do is divide the number of pixels in your image by 300.
For example, if your image is 4096 x 4096 pixels, you should divide 4096 by 300. This will give you the maximum print size of your image if you want a PPI of at least 300, in this case 13.65" x 13.65"
What does it mean when my computer says a graphic I downloaded is less than 300 DPI?
Sometimes when you open an image on your computer, you will see that there is a DPI value
We strongly suggest that you ignore this number as it is not useful on it's own, without knowing what size you want to print the image.
This number comes from the metadata of your image, and does not reflect the quality of the image. In fact, you can change this number by editing the metadata - this will neither increase nor decrease the quality of your image.
Here's an example - these three images have the same number of pixels (4096 x 4096) but different PPI values - they are all the same size and quality!
| 1 PPI | 96 PPI | 300 PPI |
| 4096 x 4096 px | 4096 x 4096 px | 4096 x 4096 px |
| 16.5 mb | 16.5 mb | 16.5 mb |
You can test this yourself by right-clicking and saving these images on your computer!