How to chose the number of shards and replica

Elastic Stack Elasticsearch
1

Hello everybody,

Could you tell me please what is the best rule to calculate the number of shards for the index ? I found this rule but I don't know if it's the best one:

20 Shards max for each 1 GB of heap on each node

And how can I chose the number of replicas ?

Thanks for your help.

2

Try to make sure each shard is between 10GB and 50GB in size.

3

Thanks for your reply @Christian_Dahlqvist

I configured the size of shards to 20GB, but I don't know how many shards and replica to chose.
In my cluser I have 3 master nodes and 2 Data nodes
The three master Nodes are configured for hot data and the 1st Data node for warm and the last one for cold data