DPI (Dots Per Inch) is a measurement that indicates how many dots of ink a printer places within one inch of paper. It is a crucial specification for print quality – higher DPI means more detail and sharper prints. It is often confused with PPI (Pixels Per Inch), but they measure different things: DPI relates to printing, while PPI relates to digital displays.
What does it mean?
This measurement determines print resolution and directly affects the sharpness and detail of printed images. A standard office printer typically operates at 300-600 dots per inch, while professional photo printers can reach 1200-4800. The higher this value, the more ink dots are placed per inch, resulting in smoother gradients and finer details.
Comparison with PPI – what’s the difference?
While often used interchangeably, DPI and PPI refer to different concepts. PPI describes the pixel density of a digital image or screen, while DPI specifically refers to the output resolution of a printer. When preparing images for print, the source file’s PPI is converted to DPI by the printer driver.
For example, a 3000×2000 pixel image printed at 300 DPI will produce a 10×6.67 inch print. The same image at 150 DPI would create a 20×13.33 inch print, but with noticeably less detail and sharpness.
Recommended settings
The optimal setting depends on the viewing distance and purpose of the print:
- 300 – standard for photo prints, magazines, and detailed graphics
- 150-200 – suitable for posters and prints viewed from a distance
- 72-100 – acceptable for large banners and billboards
- 600+ – used for fine art reproduction and high-quality photo printing
How to check and change resolution
Most image editing software allows you to view and modify resolution settings. In Adobe Photoshop, go to Image > Image Size to see these values. Programs like GIMP, Lightroom, and even online tools can adjust the resolution without changing the pixel dimensions of your image.
Important: changing only this value (without resampling) doesn’t add or remove pixels – it only affects the print size. To increase actual detail, you need more pixels in the source image.
Frequently Asked Questions
Learn more about DPI on Wikipedia.
