There is no "one size fits all" answer to this question; it will depend on what your goals are. However, here are some guidelines to help you figure it out:
To gain and/or maintain muscle, most studies suggest that 0.7–1 grams per pound of lean mass (1.6–2.2 grams per kg) are sufficient.
Lean mass is the calculation of your body weight, without fat. The simplest calculation is: total weight * ((100 - body fat percentage) / 100)
For ex: 210lbs * ((100 - 15%) / 100) = 178.5lbs
This means to build / maintain muscle, you should consume between: 178.5 * .7 = 124.95g and 178.5g of protein
The average dieter needs 0.4 - 0.5 grams of protein per pound of lean mass.
Note: you can get too much protein! According to the Harvard Medical School, 2 grams or more of protein per kilogram of body weight can be harmful.
Excessive consumption of protein can result in:
Cholesterol that results in a higher chance of heart disease.
Digestive system issues, including diarrhea and constipation.