There is no official way to see your MMR in LoL. For now you can only guess a certain range by keeping an eye on the LP distribution after ranked games. Some websites offer a service that gives out a general idea for players.
Find us at the office
Duffle- Fyle street no. 48, 82141 Montevideo, Uruguay
Give us a ring
+74 935 689 322
Mon - Fri, 9:00-23:00