Calculate image DPI/PPI, assess print quality, convert pixels and physical dimensions
Suitable for general printing needs, such as documents and photos
DPI (Dots Per Inch) represents the number of dots per inch, used to measure the print quality of an image. The higher the DPI, the sharper and more detailed the printed image. PPI (Pixels Per Inch) has the same meaning as DPI in digital images.
Choose based on purpose: 72-96 DPI for web use; 150-200 DPI for home photo printing; 300 DPI for professional photography and design; Large posters can use 150 DPI (due to longer viewing distance).
• DPI = Pixels ÷ Physical Size (inches)
• Pixels = DPI × Physical Size (inches)
• Physical Size = Pixels ÷ DPI
Select based on known information: Calculate DPI, Calculate Pixels, or Calculate Physical Size
Enter known dimension data. DPI calculation mode supports image upload for automatic pixel dimensions
Check calculation results and quality assessment, get targeted printing or display recommendations
Use Case: You have an image file and need to confirm print quality
Required Input: Image pixel dimensions (can auto-detect from upload) + desired print physical size
Result: Image DPI value and print quality assessment
Use Case: Need to create an image with specific physical size and quality
Required Input: Target DPI (e.g., 300) + desired physical dimensions
Result: Required pixel dimensions for the image
Use Case: You have an image and need to determine maximum print size
Required Input: Image pixel dimensions + desired print quality (DPI)
Result: Maximum print size at specified DPI
DPI (Dots Per Inch) typically refers to printer physical output resolution, while PPI (Pixels Per Inch) describes digital image resolution. In digital image processing, they are often used interchangeably and have essentially the same meaning.
300 DPI is standard because the human eye cannot distinguish higher dot densities at normal viewing distance (about 10-12 inches). 300 DPI produces smooth edges and fine details, meeting most professional printing requirements.
Web and screen display typically only need 72-96 DPI. Screen resolution is determined by pixels, not DPI. Higher DPI only increases file size without improving display quality. Modern high-resolution screens (Retina, etc.) recommend using 2x pixel dimensions.
DPI itself is just a description of pixel density and cannot be "magically" increased. To improve print quality, you need to: 1) Rescan or reshoot from a higher resolution source; 2) Reduce print size; 3) Use professional upsampling software (but with limited results). Simply "changing" the DPI value in software won't improve actual quality.
No. Large posters are typically viewed from a distance and can use lower DPI (e.g., 100-150 DPI). For example, a poster viewed from 10 feet away at 100 DPI provides the same clarity as a 300 DPI photo viewed up close. The greater the viewing distance, the lower the required DPI.
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