I love using “Print Size” in the Photoshop “View” menu as it allows me to see how big the image will print in the physical (real) world.
The chances are that if you try this with an image in your Photoshop the result will be incorrect (for instance a 10″ image may be nearer 7″ on screen). The reason for this is that by default Photoshop assumes you are using an early Apple monitor that has a resolution of 72dpi. In actual fact most modern monitors display many more dots per inch (pixels per inch) hence making the print preview too small. To make an accurate sized print preview you need to enter the actual dpi for your particular monitor.
You can work out the correct screen dpi to set Photoshop to by dividing your physical screen length by the horizontal resolution, for example my Eizo CG303W monitor is driven at its native resolution of 2560 x 1600 pixels and is 25.3″ wide so:
2560/25.3 = 101dpi
If you don’t have a long ruler you can work out a good approximation of your screen dpi by using the calculator above, just follow these steps:
- In Photoshop select “File: New” make sure the units is set to inches and create a canvas that is 10″ x 10″ (any dpi is good) and click “Ok” to display it. Then click on the “View” menu and select “Print Size“. Use a ruler to measure the actual canvas size and fill in the values in the form above, the form will then calculate the recommended dpi to set, (use decimal values so for instance seven and a quarter inches is entered as 7.25)
- On a mac select “Preferences” from the Photoshop menu and click on the “Units and Rulers” section
On a PC select from the “Edit” menu: “Preferences” and then click on the “Units and Rulers” section
- In the “New Document Presets and Resolutions” section change the “Screen Resolution” value to the calculated dpi shown by the form (Make sure that “Pixels/Inch” is selected in the dropdown to the right). Click “Ok” to come out of the preferences.
- Click on the “View” menu once more and select “Print Size” to update the display. Measure the image again and it should now be pretty much bang on.
If your measurements are a bit off then not to worry, just increment the Screen dpi setting in the Photoshop preferences as follows:
If the measured image is slightly too big then add 1 to the set dpi in Photoshop
If the measured images is too small then subtract 1 from the set dpi in Photoshop
Go back into preferences and change the dpi then after exiting preferences you will need to select “View” and “Print Size” each time to refresh the display before measuring. Repeat steps 1-3 until your canvas is the correct size according to your ruler.
The end result will be the ability to display any size image correctly on the display, if you are printing an image to go into a photo frame you will be able to hold the frame in front of the monitor and see how it will look. Or in the case of repro see how the technical quality stands up to double page repro etc.
Most modern monitors are between 90 – 110 dpi though you may find 4k or Mac monitors to have a much higher dpi value.
(Note: if your screen is too small to display a 10″ image (perhaps its a laptop) then create a smaller canvas size and update the second field in the form to reflect this, if your Photoshop is initially set to something other than 72dpi then put the initial dpi into the first field of the form as well, this form allows you to calculate any size image, best to use a size that fits on your screen and is within the bounds of your ruler)