Printing an image at a given size and resolution.
Divide the longest edge of your image (measured in pixels) by the longest edge of your desired print size (measured in inches). For example, if an image measures 3,840 x 5,760 pixels and you want an 8- x 10-inch print, take the longest edge in pixels and divide it by the longest edge in inches of the target print size: 5,760 pixels ÷ 10 inches = 576 ppi (pixels per inch). That’s more than enough resolution to produce an awesome print; remember, you need a minimum of 240 ppi though it really depends on the printer. However, if you want to make a 30- x 20-inch poster out of that image, you’d have a resolution of 192 ppi (5,760 ÷ 30), which isn’t high enough to print well.
FIVE THOUGHTS ON PRINTING BIGGER
Shadows Open up – Print Down a Little
Textured Papers Work Better With Bigger Prints
Resolution Required Depends Greatly on Expected Viewing Distance
Original File Quality
Handling and Framing Considerations
Big prints show off flaws in your source material, but keep this in perspective. You will always be the fiercest critic of your own work.