While playing online chess, a number of games at the same time, my rating changes as I win or loose games. Based on which rating it is calculated; the rating that started any particular game, or the rating I have at the end of any such game? For example I start a game at a rating of 1320 vs 1450. When the game finish, I am at say 1410, and the opponent is 1370. How is it then rated?
I assume you are talking about online correspondence-type games (aka "Daily" chess). Those games are rated using the most current ratings for you and your opponent when you finish the game.
That is the only possibility to maintain sanity in the ratings. Some correspondence games can go on for a year or longer. Some players play hundreds or even thousands of games at the same time.
While playing online chess, a number of games at the same time, my rating changes as I win or loose games. Based on which rating it is calculated; the rating that started any particular game, or the rating I have at the end of any such game? For example I start a game at a rating of 1320 vs 1450. When the game finish, I am at say 1410, and the opponent is 1370. How is it then rated?