I'm often told of cat behavior "problems" that relate back to cats being hungry. Many of the aggression issues, and late night howling are related to a cat feeling hunger pains and anxiety/worry about the source of the next meal. Here is how you figure out how much to feed your cat:
kg to pounds - calculate how many kg your cat weighs (1kg = 2.2lbs) An average 10 pound cat = 4.54kgs
kcal - find the kcal per serving on the food you're feeding.
A neutered/spayed cat needs 60 kcal per kg/day
For example: 10 pound cat needs about 270 kcal/day
On this example below (3oz. can of Merrick Chicken Pate) there are 110 kcal/3oz. can, which means I'd need to feed 2.5 cans per day. Remember, the 270 kcal is total, including dry food and treats.
If your cat is older and/or inactive, the kcal requirements drop to 40-60 kcal/kg