DPI vs PPI – Key Differences
DPI relates solely to printing and determines how many physical dots of ink a printer applies to an inch of paper. PPI, on the other hand, defines the number of pixels per inch on the screen. In practice, this means that the same file can be of identical quality at different DPI values, as the actual number of pixels in the image is decisive.
DPI in Print
In printing, the standard is to use 300 DPI for materials viewed up close (leaflets, business cards, catalogues). For large-format prints, viewed from a greater distance, even 150 DPI may be sufficient. Photo printers often use a resolution of 600 DPI or more for the highest quality prints.
DPI on the Web
In a digital environment, the DPI value has no meaning. Screens display pixels, not print dots. When preparing graphics for a website, only the number of pixels matters. The popular belief in a 72 DPI standard for the web is rather conventional and dates back to the time of the first Apple Macintosh monitors.
FAQ
What does DPI mean?
DPI (Dots Per Inch) refers to the number of printed dots that fit within a one-inch line. It’s a measurement of resolution primarily used in printing and determines print quality. Higher DPI values result in more detailed and higher quality printed images.
What is 300 DPI?
300 DPI means there are 300 dots per inch (2.54 cm) of the image. This is the standard resolution used in professional printing, providing high quality and detailed outputs, especially for photographs and graphics.
Is 300 DPI a lot?
300 DPI is the optimal value for most professional printing needs. It’s sufficient for creating high-quality printed materials such as brochures, catalogs, and photographs. Higher DPI values rarely provide noticeable quality improvements.
What is the best DPI resolution?
For professional printing, 300 DPI is the best resolution. Office documents can use 150-200 DPI, while large format banners viewed from a distance may only need 72-150 DPI. The choice depends on the final application.
How do I check image DPI?
You can check image DPI in graphic software like Photoshop (Image > Image Size menu) or in file properties on your computer. In Windows, right-click the file and select Properties to view resolution details.
Practical Applications
Preparation for Printing
When preparing material for print, it is important to remember:
- Maintaining the correct resolution (min. 300 DPI)
- Consideration of the actual print size
- Conversion of the number of pixels into the final format
- Correct colour calibration
- Correct file format (JPG or PDF)
Importantly, a 3,000×2,000 pixel file will have the same print quality regardless of whether you set it to 72 or 300 DPI in your graphics programme. The key is the actual number of pixels and the physical size of the print.
Preparing for the Web
For web graphics, the focus should be on:
- The actual dimensions in pixels
- Optimal file compression for fast loading
- Correct format (JPG, PNG, WebP)
- Size suitable for the target device
- Provision of different formats for responsiveness
Popular Myths About DPI
The myth that 72 DPI is required on the web is one of the most popular misconceptions in the industry. It is not required and, as we mentioned earlier, rather conventional. The DPI parameter in web files does not affect the quality of the display – this is determined solely by the number of pixels. Today’s monitors have different physical resolutions, often well in excess of 72 PPI.
Why Is DPI Important in Print?
In printing, a high DPI value is important because it affects the detail and sharpness of the print. At 300 DPI, the dots are so small and densely packed that the human eye, from a normal distance, cannot distinguish them, giving the impression of a uniform, sharp image.
How Do I Calculate the Correct Resolution?
To calculate the required number of pixels for a print, multiply the dimensions in inches by the desired DPI. For example, for an A4 print (approximately 8.3 x 11.7 inches) at 300 DPI, we need an image of 2490 x 3510 pixels.
How Does This Currently Look?
Nowadays, thanks to developments in display technology, the boundary between preparing material for print and for the web is becoming increasingly smooth. High-resolution monitors (Retina, 4K, 5K) require graphics with significantly more pixels than the traditional 72 PPI, although this still has nothing to do with DPI.
