Apple 27″ Thunderbolt Display has a pixel density of:
108.79

A.K.A. Thunderbolt Display (27-Inch)
Released: 2011

Resolution: 2560×1440 27″ display

Quad HD (QHD) 2560×1440, 16:9 aspect ratio

Totaling 3.69mp (megapixels) and having a PPI of 108.79

Category: Desktop LCD
Tags: apple, thunderbolt, display, mac

Apple Thunderbolt Display

The Apple Thunderbolt Display
Developer	Apple Inc.
Type	Computer monitor
Release date	July 20, 2011; 8 years ago (2011-07-20)
Discontinued	June 23, 2016 (2016-06-23)
Predecessor	Apple LED Cinema Display
Successor	LG UltraFine (consumer) Pro Display XDR (professional)
Website	Official website

This righthand infobox courtesy of Wikipedia.