When i look for (Diablo 3 Difficulty Overview) on Google, a chart says at GR1 - Greater rift key is (1 + 5% of having 2). But when i end GR1 i have no key. I am missing something? Also, Anyone know what GR level i need to have a guaranteed Greater rift key (except for normal) ?
Thank you
Greater Rifts do not drop keys, they consume them.
Nephalem Rifts drop GR keystones.
edit: Google is not always your friend. 
Sometimes it will link to outdated (or wrong, in this case) information.
Try looking up your nearest Radio Shack or Sports Authority.
So even those crazy Torment 15 farmer need to farm a normal rift every single time before doing a Greater rift?
Tx for help
If you want to see the drop rates of things like GR keys at certain difficulty levels…
https://d3resource.com/difficulties/index.php
Basically yes … Normal rifts provide Greater Rift keystone drops when you beat the Rift Guardian … the higher the Torment level, the higher number of keystone drops will occur. This is one of the reasons why players will speed through Normal Rifts mainly farming for keystones and leave them after the Rift Guardian is dead, rather than finishing the rift to completion.
Ohhhh now i understand my mistake. Greater rift does not drop Key, but if i do Normal Rift at Torment 10, i have 1 key + 90% of having a 2nd. Is that correct ?
Yes that is correct. There are ways of increasing your chances of getting more keys, like Cain’s level 70 set, but there is a right way and wrong way to use it.
Ty all for your help!
Yes, but at your level, you’d be better off running T2s for a bit.
T10 would be very frustrating, if even possible.
And to add to what others have said: On T15 you get 3 Keystones with a 5% chance to get 4. So, at T15 and T16 you can run a couple of Rifts and then run 6 to 8 Greater Rifts.
At lower Game Difficulties, I like to run Rifts mainly to farm for gear, Death’s Breaths and add to my Gold reserve. (Gathering Keystones is merely a “side effect”).
By the time I can farm T10 through T16 I have enough Keystones stashed that I can run many Greater Rifts without interruption.
Of course, the exception is getting 3 Legendary Gems I can use. Even if they’re not the right LGems for my build. It not only benefits my Character, but completes some of the Season Journey Objectives. (Getting 3 LGems to Rank 25, etc.)
Note: At lower Greater Rift Levels it’s not as easy to level LGems with 100% chance of success. To level one Rank 0 Gem to Rank 4 at 100% chance requires starting with Greater Rift 13.