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Image Size Calculator

Pixels Explained

Convert pixels to inches (Output to Monitors/Printers)
Formula: Pixels ÷ DPI = Inches

Image Width: Pixels
Image Height: Pixels

Select the resolution
of the output device
Image Width: inches
Image Height: inches
If you know the pixel width and height of an image, this section will calculate the physical size (in inches) of the image when it is printed or displayed on various devices.

To use the calculator, enter the width and height, then select the output resolution which will be used.

* Most monitors display images at approximately 75DPI. To check your own monitor, use the chart below.

** Many printers use a process known as Image Refinement when processing images. This may impact the relation between input and output resolution. Generally, 300DPI is adequate for photo-like prints.

Convert inches to Pixels (Input from Scanners)
Formula: Inches X DPI = Pixels

Photo Width: inches
Photo Height: inches
Select the DPI setting
of the Scanner
Image Width: Pixels
Image Height: Pixels

Scanners typically allow the DPI resolution to be adjusted via software. For best results, scanning should be done at the resolution of the intended output device.

Example: You wish to scan an item of jewelry and print the item in your catalog with the caption "Shown Actual Size."

If the catalog will be printed on a 600 DPI printer, the item should be scanned with a resolution of 600 DPI, and care should be taken not to re-size or resample the intermediate image file before printing.

When the output destination is a computer screen, as in the case of auction photos, the scanned image may require further reduction using an image editor before the image is physically small enough to fit on the viewer's screen.

Example: a book cover measuring 8 in. by 10 in. will produce an image height of 750 Pixels even when scanned at only 75 DPI. Because many computer displays are set at 800 X 600 Pixels, the resulting photo will be taller that the display area and force scrolling.

Handy Tip! If you plan to create a new logo or graphic using an image editor, Start by deciding the DPI setting which will be used to print your design. You can then enter the desired size of the graphic above and calculate the Pixel dimensions needed for the best print quality. (Your original work can be resampled for an appropriate size web image)

Monitor & Display Resolution

To determine the DPI resolution of your current display setting, measure the width of the red line above with a household tape or ruler. Consult the table at right to locate your measurement. The result will be about four inches on most monitors. This is a common measurement and explains why you will often see 75 DPI used when discussing display resolution.
 Measurement  Screen DPI 
 3 inches100 DPI
 3 ¼ inches92 DPI
 3 ½ inches85 DPI
 3 ¾ inches80 DPI
 4 inches75 DPI
 4 ¼ inches70 DPI
 4 ½ inches66 DPI
 4 ¾ inches63 DPI
 5 inches60 DPI

What is a pixel? What is DPI? (Dots Per Inch)

You may think you don't know what a pixel is, but, If you've ever seen a card stunt at a sports event, you probably do! A pixel is simply the individual point of color on a digital image. A pixel doesn't have a particular size. It is an abstract represention of a specific coordinate, like a point on a map. Just as individual sports fans hold up a colored card in the stadium, individual pixels light up on your display to form a pattern. The only difference is the size of the point when it is displayed.

This same concept extends to many other digital products. Pixel is used to describe the number of descrete points that can be captured by digital cameras, and because most cameras can actually recognize millions of points, the term Megapixel is used to shorten the number of zeros needed.

Pixel indicates only a point on a grid, not the size of the point. Instead, Pixels create a pattern based on the scale of the device being used. The photo shown here is a good example. When the display device is the size of a stadium, the individual pixels are the size of cards held by the people. When the display is the size of the screen you are looking at, the pixels are so small that you may not be able to see them individually.

For Printers and scanners, the individual points of color are often called 'dots' rather than pixels, but the concept remains the same as the stadium. Because the output of a printer is paper which is usually measured in inches, the term DPI or Dots Per Inch is used to communicate the scale or physical size of each pixel. Just as it takes many people seated in a grid to display a card stunt at the stadium, a printer must place dots of color on paper to create a photo.

The scanner performs this function in reverse, by recognizing the color at a specific row and column on the item being scanned. The scanner or digital camera actually records a file of information indicating what color appeared at what position in the picture. This is again the same principle as that of row and seat in the stadium.

Common Display and Capture Devices
DevicePixel SizeDPI
Footbal Stadiumabout 2 square ft.0.041
Giant Scoreboardabout 1 ½ inches0.66
50 ft Digital Cinema Screenabout 1/3rd inch3.33
Computer Displayabout 1/75th of an inch 75
Computer Printer about 1/300th of an inch 300
Digital Scanner ~ 0.00083 inch 1200
Digital Camera ~ 0.00035 inch 3500