Question regarding density altitude formula calculations

This is a copy of the original post body for posterity: --- Just trying to sanity check my understanding here. Let's say we are at 4000ft indicated altitude. METAR reports the following: A30.00 OAT = 10deg celsius (at airport elevation of 30ft) To calculate pressure altitude, I did the following: PA = 4000 + \[1000 x (29.92 - 30.00)\] PA = 3920ft Now to calculate the density altitude, first I have to figure out the temperature deviation so at 4000ft indicated altitude, standard air temperature would be 15 - 8 = 7, and (here I'm not sure if I'm doing this right or not) the OAT at 4000ft would be 10 - 8 = 2 correct? So then if I plug this in my density altitude formula DA = 3920 + (120 x (2 - 7)) DA = 3320ft So at an indicated altitude of 4000ft with a pressure altitude of 3920ft, my density altitude will be 3320ft, which in my head makes sense because it's colder and we have higher pressure in the area so I can expect better performance. The part I'm not sure in my calculation is the OAT. Did I correctly use the write number here when I did 10 - 8 =2 or am I supposed to use 10 for OAT? --- Please downvote this comment until it collapses. Questions about this comment? [Please see this wiki post before contacting the mods](https://www.reddit.com/r/flying/wiki/index/rflyingtower/). --- I am a bot, and this action was performed automatically. If you have any questions, please [contact the mods of this subreddit](https://www.reddit.com/message/compose?to=/r/flying).