While there’s no way to directly check your MMR there are websites that will give you an almost perfect estimation by taking the average MMR of your recently played ranked games. MMR is important because despite being hidden its your true Rank, and the amount of LP you get per win is determined by your MMR. If your MMR is really good you can skip divisions and promotional series, as well as have ridiculously high LP gains. If your MMR is bad you struggle with low point gains, you often win less points than you lose during a loss, and risk of potential demotion. If you are trying to check your MMR follow the guide below:
Step 1 –
Play 5 ranked Solo queue games. In order for the website to give you an accurate estimation of your MMR you need to have recent ranked games on your match history, and they need to be solo queue. This is because when you solo queue the game is purely your MMR, and not some combination of your MMR + friend(s). But make sure you have 5 recent ranked games on your match history, and if you don’t than go play 5 ranked games then proceed to Step 2.
Step 2 –
Go to op.gg and search for your accounts name. If you are on a server other than NA you first need to click the globe icon on the op.gg summoner search bar and select the proper region. Once you are on this page first hit [Renew] so it updates your summoner data, and then hit [Solo MMR] once that is done loading to have your MMR calculated.
The number value that it gives you is your current MMR, and next to that is the appropriate Tier/Division for your current MMR. Below that you can see the average MMR for your current Division/League. Remember, if you have any duo/flex queue games in your recent match history this number will be inaccurate as it’s factoring in non solo games.