Different types of food have varying levels of calorie density; however in general each meal will be 1-2 cups of dog food.
Free feeding is not recommended. This is a method in which a dog's food is left out, so that the dog may eat when the desire. For maintaining good health and avoiding bloat
and other issues, food should be given at allotted times throughout the day; this is best for the dog.
Most owners find it easy to feed their puppy the 3 meals at the same time that they eat their own breakfast, lunch and dinner.
6 Months to 1 Year
During this time, despite appearance, your Boxer is still considered a puppy. During this 6 month time period that leads up to the 1 year mark, work your way down to 2 meals a day; 1 in the morning and 1 in the early evening. While many other dog breeds do well with 1 meal per day, since the Boxer is so prone to bloat, maintaining a schedule of feeding a Boxer twice per day is best. Since treats and snacks should be given to reinforce good behavior, factor that in when doling out meal sizes. You'll want your Boxer to appreciate the reward of a treat.
2 Years Old
Congratulations! Your Boxer is now considered an adult dog. Again, while many other breeds are now down to once-a-day feedings, to prevent bloat it is recommended to continue with 2 meals a day. You may opt to offer a smaller meal in the morning and a larger one at night. Alternatively, if your Boxer is left home alone
you may find it best for the first 'morning' feeding to be food that is stuffed into a Kong to be eaten over a period of time.
Your Boxer is done growing now, so do be careful to not overfeed. Extra calories are not needed, as growth spurts are done.