Calculations with Optical Instruments

Print Size, Image Size and Resolution in DPI

A calculator for the size of an image in pixels, for the size of the print in centimeters, inches and other units and for the resolution in dpi, dots per inches, the common units for print products. For a good print quality, typically at least 100 dpi are recommended.
Please enter three values at image and print size or enter the resolution in dpi and both values either of the image size or of the print size. The remaining two values will be calculated.

Example: an image of the size 1500 times 1000 pixels shall be printed with a width of 30 cm. The print height then will be 20 cm, the resolution is 127 dpi.

A dot on paper is different from a pixel on a screen. Depending on the dpi and ppi values, a dot can be larger or smaller than a pixel. Many screens display 96 ppi (pixels per inch). However, some other monitors have higher values. With a screen resolution of 96 ppi and a dot density of 96 dpi, the dot and pixel would be the same size. At a lower quality level when printing, the dot is larger. However, printing is usually done at a higher quality. At 300 dpi, which is a lower standard for good print quality, a dot contains just over three pixels. The ratio can be calculated analogously for other screen resolutions.

	Width	Height	Unit
Image size:			Pixel
Print size:

Resolution:			dpi