Estmation of hardware needed

Hi, this is a very broad question and I guess the answer will have lot's of "it depends" but i'm just trying to get some general idea and not an exact answer.
I am using Elasticsearch to index and search web pages (human readable text only, no html). for each page there is a title text field and a body text field. queries are similar to a general search engine.
It's working great but as I index more pages searching obviously gets slower and I wanted to know:
If I want to go to about 1 billion pages and have searches return in about 1 second, what size of hardware do I roughly need?


What's acceptable performance? At what level of docs and nodes is that? If you add more data, how many more nodes/resources do you need to add to get acceptable performance?

You really need to test and figure it out yourself.