Display resolution (dpi)

Hi,
I was doing some scaling from my private pictures and wanted to fit the size perfectly on my mbp display.

So, I knew, I have a native resolution of 1680x1050, but there is a third factor: The dpi.
The "standard" is 72 dpi for all pictures you want to see on a display, but I know, the display of the mbp has got a much higher resolution than 72 dpi.
Is there anywhere a page with the exact data of my screen?

I've read something about 120 dpi, but I dont know, if this is right.

Thank you 🙂