Standard Day
1” of Mercury = 1,000’
So if you change the altimeter setting from 29.15 to 29.85, that’s a increase of 0.70”, which means it will be an increase in altitude of 700’
Standard day is: 29.92 Hg and 15 degreed Celcius
Pressure Altitude = (standard pressure - current pressure setting) x 1,000 + field elevation
Density Altitude = Pressure altitude + [120 x (OAT - ISA Temp)]