The ratio for the perfect balance of coffee & water is called the "Golden Ratio." This ratio was developed by the SCAA (Specialty Coffee Association of America) to ensure the best cup of coffee or The Golden Cup Standard.
One of the biggest questions we hear from new home coffee brewers or K-cup converts (bless your soul) is "how much coffee do I use to make ___cups of coffee?" Learning a new brew method or experimenting with the right recipe can make you feel like a mad scientist or just leave you confused & with a bad cup of coffee. We get it, not everyone is a coffee nerd like us or you just don't have the time, we are here to guide you in the right direction.
The best answer is: 10 grams of ground coffee per 180 ml of water (180g of water). This requires a scale, which is a worthwhile investment if you care about the quality of your coffee, but a lot of people just want to keep things simple.
The simple answer is: for most home coffee brewing is 2 Tbsp. (10.6 g) of ground coffee beans per 6 oz. of water. A standard coffee measure should be 2 Tbsp. (2 Tbsp. = 1/8 cup = 10.6 g).
The SCAA defines 10 grams or 0.36 oz. per 6-oz cup as the proper measure for brewed coffee using the American standards.
It needs to be pointed out that some coffee pot manufacturers deviate from the 6 oz. per cup standard. You should check the total water capacity of your pot before assuming that the pot will be measured in 6 oz. cups.
Coffee Grind: Coffee beans should be ground right before brewing to extract the freshest, most consistent flavor & have minimal air contact which can drastically change coffee flavor.
Water Temperature: Water Temperature is also very important. Too cold of water will result in flat, under extracted coffee, while water that is too hot will cause coffee flavor to degrade. Water temperature at the time of contact with the coffee should be 200°F (93.0°C) (plus or minus 5° variation)
Brewing Time: The amount of time the water is in contact with the coffee grounds is another very important factor. Depending on your brew type the timing changes. In a drip system it should be around 5 min. French Press, contact time should be around 2-4 min. for espresso....that is whole another post :)