For my Mac’s settings, (1800 pixels / 11.875 inches) * 2 = 303 ppi, and entering that in Screen Resolution lets Print Size show the Photoshop ruler at an on-screen size that matches a real ruler.Īlso important: For both Actual Size and Print Size to work properly, the document physical dimensions in inches/cm and the PPI resolution (you set both in Image > Image Size) must match the final reproduction dimensions and resolution. For a Retina/HiDPI display, take the pixel width from the UI scaling selected in Displays, as gener7 showed, and then after doing the calculation, double the result to compensate for 2x pixel density so that you get the correct number for Screen Resolution. Important: It gets tricky on a Retina (macOS) or HiDPI (Windows) display, which use 2x pixel density. Accurate, user-friendly, supports both cm and inches. Credit Card: 3.375 inches by 2.125 inches. Online ruler to quickly measure objects on any device with any screen size. For example, a US dollar bill should be exactly 2.61 inches wide, you can now compare that to our online ruler size and your screen size.

If you don’t know the display resolution, you can work it out yourself using the method gener7 showed earlier in this thread. You can check if the screen ruler is the actual size by measuring a 'standard' bank note. If Actual Size is not accurate, use View > Print Size after manually calibrating it by entering your screen resolution in Preferences / Units and Rulers / Screen Resolution. It does match up perfectly when your eye is directly above each marker.)Īctual Size might not be accurate with some computer and graphics hardware combinations. (It may look slightly off in the photo, but that is due to close up parallax. After your first mark, add another light mark to your board every 12 inches. And you don’t have to know what any of the numbers are, it just works. How to adjusting this virtual ruler to actual size. Using a pencil mark, lightly mark the board.

When Actual Size is used, Photoshop gets the display pixel density from the Mac hardware, and uses that to correct the display magnification, so the Photoshop ruler matches the real ruler that is against the screen.

The screen shot posted earlier by gener7 is from a Mac.īelow is the ruler in Photoshop on my MacBook Pro after choosing View > Actual Size in Photoshop. In addition, it allows you to select the graduation of an inch. Also, you can get the size in centimeters and inches. By using this tool, you can change the PPI and calibrate it according to the size of the placed object. The Actual Size command works automatically on a Mac.Īll of the replies I posted are from my Mac. Ruler Online is another virtual tool to identify any object’s size.

Live action ruler life size ruler