Infra details clarification

How to decide number of logstash nodes for elastic nodes. Is there is any ratio or calculations are there ?

for example, i have 1TB of logs per day, i want to have online retention of 30 days at any point of time.

In this case, totaly 30TB is required from elastic search and we can have 4 elastic search node with each 10TB of memory with 64GB RAM without replica.

how many logstash and can be planned.