By default the measurement unit for the Type tool is Points. Whichever value you enter in the Font Size box will be converted into points. You can change the measurement unit by going to Edit>Preferences>Units & Rulers>Units>Type . . .
Elements 7,10,11,12,13,14,15 - Photoshop CC 2017 - Lightroom CC 2015 Windows 7 Pro & Windows 10 Pro