You can convert calories into nutrient's quantity like this:
- 1 gram of fat = 9 Calories
- 1 gram of carbs = 4 Calories
- 1 gram of protein = 4 Calories
So If you want your intake of calories from fat
Amount of fat (grams) =
(Daily Calorie Intake) X (Percentage of Calories from fat/100)/Calories per gram in fat
Now if your daily calorie intake is say 2000 Cals,
Amount of fat (grams) = 2000 X (30/100)/9 = 66.66 grams of fat
Please note that, this is only arithmetic. You have to see the quality and type of fat also. Because all fats including saturated, unsaturated, transfats and cholesterol have the same no. of Calories per gram, but all fats are not equally heathy. Especially transfats found in pizza, cake, burger, fried chips and other fast foods is unhealthy