![]() A formula on this line calculates the dpi used to make the print by dividing it’s width in pixels by its width in inches.The DPI calculator also referred to as the mouse DPI calculator, is used to calculate the dots in one inch of the display. A formula on this line calculates the height of the print so it has the same aspect ratio as the digital image.ĥ. Enter with desired width of your printout on this line.Ĥ. This figure and Part 3b on the Excel worksheet " Image Size Calculator" calculates the dpi of a print when you use a program that automatically resizes a file for printing.ģ. When you know the width of the image in pixels, you can divide that number by the printer’s dpi to determine the largest possible print size in inches. For example, if you print an image that’s 1600 pixels wide so the print is 10" wide, there are only 160 dots per inch (unless its resampled) (1600 pixels ÷ 10 inches = 160 pixels per inch). To find out what the pixels (or dots) per inch becomes, you convert from the image's original size in pixels to its pixels per inch. When you enlarge or reduce an image like this, the ppi change. Let's say you have a scanned image and want to print it at a certain size. If your printer can print a sharp image only at 300 or more pixels per inch, you need to determine if the size of the image you plan on printing will fall below this level. Pixels begin to show when the print is enlarged to a point where the pixels get get so big that the pixels per inch (ppi) fall too low. That’s because a certain minimal number of dots per inch, usually about 300, are needed to get a good print. One thing to keep in mind is that if you enlarge a print too much, it won’t be as sharp as you may desire. For example, if you place an image in a program such as QuarkXpress or PageMaker, its printed at the size you specify in those programs. That task is handled by the software program you use to print the image. Normally you don’t have to change the number of pixel’s in an image to change the size of a printout. Original 1800 x 1600, printed at 600 dpi is _ x _ Understanding pixels per inch (may be a new section) Original 1800 x 1600, printed at 300 dpi is _ x _ Original 1600 x 1200, printed at 600 dpi is _ x _ Original 1600 x 1200, printed at 300 dpi is _ x _ Original 800 x 600, printed at 600 dpi is _ x _ Original 800 x 600, printed at 300 dpi is _ x _ Using the widths and heights listed in the "Original" column and the specified printer dpi’s, calculate the width and height of the prints you’d get. If your printer prints 300 dpi, how wide will an image have to be in pixels, to get a 6-inch wide print?Ĥ. If your image is 800 x 600 and your printer’s resolution is 300 dpi, how big will the print be?ģ. If your image is 1600 x 1200 and your printer’s resolution is 600 dpi, how big will the print be?Ģ. A formula on this line calculates the vertical size (height) of the image in inches by dividing the image’s height in pixels by the printer’s dpi. A formula on this line calculates the horizontal size (width) of the image in inches by dividing the image’s width in pixels by the printer’s dpi.ĥ. Enter the number of dots per inch (dpi) printed by your printer on this line.Ĥ. Enter the height of the digital image in pixels on this line.ģ. Enter the width of the digital image in pixels on this line.Ģ. This figure and Part 3a on the Excel worksheet "Image Size Calculator" calculate the size of print you can expect from a given file size and printer resolution.ġ. This graphic shows how a 640 x 480 image displays or prints on devices with different dots per inch. However, if the output device prints 600 ppi, the result changes to a 2.5" x 2" print as follows: For example, to convert the dimensions for a 1500 x 1200 image being printed at 300 ppi you divide as follows: To do so, you divide the image's dimension in pixels by the resolution of the device in pixels per inch (ppi). Since image sizes are described in pixels and photographic prints in inches, you have to convert from pixels to inches. ![]() To download the unzipped version (20 Kilobytes), click here.įor comparison purposes, monitors use an average of 72 ppi to display text and images, ink-jet printers range up to 1700 dpi or so, and commercial typesetting machines range between 1,000 and 2,400 dpi. The worksheet has been saved in Excel 5 format so that version and all later versions can read it. However, to make it easier to explore the various relationships being discussed, you can download an Excel worksheet "Image Size Calculator" that will help you better follow the discussion and explore the concepts we discuss. The calculations described in this section are nothing more than subtraction, addition, multiplication, and division.
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