As many have said, the ideal brew ratio is what tastes best to you, and you can't experiment productively to find that ratio without controlling the other variables. Even then, unless you get unhealthily obsessive and start growing your own cloned beans hydroponically (and/or start producing cloned civets) you'll find things can change from batch to batch of beans.

That being said, research has been done into preferences and can provide both a good starting point and an idea of what to expect if you stray too far outside typical ratios. Americans prefer theirs weaker(2), Europeans prefer somewhere in the middle (graph below), and Norwegians tend to prefer theirs stronger(1).

(Special Coffee Association of Europe brew chart)(3)

Links I couldn't put in owing to lack of reputation:

1. www.mountaincity.com/brewing-3.html
2. www.mountaincity.com/brewing-1.html
3. i.stack.imgur.com/9Q38R.png

As many have said, the ideal brew ratio is what tastes best to you, and you can't experiment productively to find that ratio without controlling the other variables. Even then, unless you get unhealthily obsessive and start growing your own cloned beans hydroponically (and/or start producing cloned civets) you'll find things can change from batch to batch of beans.

That being said, research has been done into preferences and can provide both a good starting point and an idea of what to expect if you stray too far outside typical ratios. Americans prefer theirs weaker  (www.mountaincity.com/brewing-1.html), Europeans prefer somewhere in the middle (graph below), and Norwegians tend to prefer theirs stronger  (www.mountaincity.com/brewing-3.html).

Special Coffee Association of Europe brew chart

As many have said, the ideal brew ratio is what tastes best to you, and you can't experiment productively to find that ratio without controlling the other variables. Even then, unless you get unhealthily obsessive and start growing your own cloned beans hydroponically (and/or start producing cloned civets) you'll find things can change from batch to batch of beans.

That being said, research has been done into preferences and can provide both a good starting point and an idea of what to expect if you stray too far outside typical ratios. Norwegians tend to prefer their coffee stronger(3), Europeans prefer somewhere in the middle (graph below), and Americans prefer theirs weaker(4) -->.

(Special Coffee Association of Europe brew chart)(5)

Links I couldn't put in owing to lack of reputation:

3. www.mountaincity.com/brewing-3.html
4. www.mountaincity.com/brewing-1.html
5. i.stack.imgur.com/9Q38R.png

As many have said, the ideal brew ratio is what tastes best to you, and you can't experiment productively to find that ratio without controlling the other variables. Even then, unless you get unhealthily obsessive and start growing your own cloned beans hydroponically (and/or start producing cloned civets) you'll find things can change from batch to batch of beans.

That being said, research has been done into preferences and can provide both a good starting point and an idea of what to expect if you stray too far outside typical ratios. Americans prefer theirs weaker(2), Europeans prefer somewhere in the middle (graph below), and Norwegians tend to prefer theirs stronger(1).

(Special Coffee Association of Europe brew chart)(3)

Links I couldn't put in owing to lack of reputation:

1. www.mountaincity.com/brewing-3.html
2. www.mountaincity.com/brewing-1.html
3. i.stack.imgur.com/9Q38R.png