With my calculations, even with ~ 9 TH it is not very reasonable and profitable at all to start the mining
Anyone has done calculations, exact how much is needed for a good start ?
And what is the best miner to buy ? Antminer S3 or other ?

And what is the best miner to buy ? Antminer S3 or other ?
First, mining profitability depends on a couple of factors like expectation of future difficulty and electricity price.
The same deal can be profitable to me but not to you.
Also, I don't think there is a "minimum hashrate" to make mining profitable.
If you don't have profit with a 1TH/s miner, buying 10 miners will just make your loss 10x larger.
I agree with you, and btw, thx for the comment, and if we want to start the BTC business now they're 95% ahead so...
With my calculations, even with ~ 9 TH it is not very reasonable and profitable at all to start the mining
Anyone has done calculations, exact how much is needed for a good start ?
And what is the best miner to buy ? Antminer S3 or other ?

And what is the best miner to buy ? Antminer S3 or other ?
First, mining profitability depends on a couple of factors like expectation of future difficulty and electricity price.
The same deal can be profitable to me but not to you.
Also, I don't think there is a "minimum hashrate" to make mining profitable.
If you don't have profit with a 1TH/s miner, buying 10 miners will just make your loss 10x larger.
I have free electricity and time to host them by myself, difficulty i am calculating like 15%. But it is still not profitable. With ants it is needed to buy PSU for every two ants, that adds tocosts a little too.
If you have free electricity and host so go for it, time is money man so do you math as quickly as you can and start making profits
