Image size changes when dragging to a new document

[Heirloom Bob]

I have a 5" x 7" image in PS (24.2.1 and Windows 10). I created a new 8.5" x 11" document and when I drag the 5" x 7" image onto the letter size document, it is significantly larger than 5" x 7".

On the otherhand, if I Place a saved version of the 5" x 7" onto the letter size document, it is the correct size.

Why does a saved document maintain dimensions yet a drag and drop does not?

Bob

[Semaphoric]

What are the PPI of your two images?

[Heirloom Bob]

The 5" x 7"is 600 and the letter sized document is 300.

[D Fosse · Accepted solution]

Photoshop doesn't work with sizes. It only works with pixels. A digital image file doesn't have a size.

The size is calculated later, using the ppi number stored with the file. Pixels per inch. Read that literally; it means exactly what it says. It explains itself.

Except when you make Smart Objects! Smart objects by design honor physical size, not pixels. That's in direct contradiction of how Photoshop "really" works; so the ppi calculation is performed behind the scenes and the image resized/resampled automatically.

If the two ppi numbers are the same, the result of that calculation = 1, so nothing happens. In other words, if you want smart objects to retain their true pixel size when placed; make sure the ppi numbers are the same.