Why does it start at 1200

Why does the rating start at 1200 not 0 like in real life. And what is the conversion to chess.com ratings to real life ones? Please help I'm confuses
0 would only corresspond to someone who knew nothing of chess. That's not the case for most people who join chess.com-- most of them already at least know some, if not most, of the rules, and some people are already quite good players even though they don't yet have chess.com ratings. Apparently 1200 is considered a good initial middle-of-the-road "guess" for a new member's rating, and from that point it can move in either direction as more input on the player's ability becomes available from their game play.
It starts at 1200 because 1199 was too low and 1201 would be just a bit too high.
best comment I have ever read in chess.com

i played some chess when i was a kid, i enjoy it today, i know how to play, I'm 925.....this is the correct place to start new people at, or maybe 100
i could cheat and keep creating new accounts and wasting 1200's time by playing in games i haven't earned the right to be in. please start new accounts at the bottom
because if you play chess as well as i do, you don't deserve to have fun

Why does the rating start at 1200 not 0 like in real life. And what is the conversion to chess.com ratings to real life ones? Please help I'm confuses
0 would only corresspond to someone who knew nothing of chess. That's not the case for most people who join chess.com-- most of them already at least know some, if not most, of the rules, and some people are already quite good players even though they don't yet have chess.com ratings. Apparently 1200 is considered a good initial middle-of-the-road "guess" for a new member's rating, and from that point it can move in either direction as more input on the player's ability becomes available from their game play.
while everything you said is true, you're missing something more important...you shouldn't be able to get into 1200 matches unless you've earned...and likewise, you shouldn't be able to get into 400 matches unless you've earned it

If you want to know your rating based on a zero scale, subtract 1200.
I assume that level of math is not above your ability.