It depends on your weight and activity level, and whether you’re trying to lose or gain weight. The most important thing is to eat a breakfast that will hold you through the morning.
I find that oatmeal (high in fiber and with a low glycemic index – the sugars are digested more slowly) with some peanut butter for protein fills me up and really “sticks to my ribs” so to speak. If I’m hungry later in the morning I try to have yogurt. That’s based on me being 205#, work in an office, and trying to lose weight. If you’re more active, you’ll want to eat more.
There are a number of apps that have free options that can help you plan your calorie intake to balance it for the day. I use Lose It!, and Under Armor makes a good tracker, too.
If you’re looking to judge what works best for you, tracking what you eat – either with paper and pen in a notebook, or with an app, will help you be more aware of how your breakfast impacts your hunger throughout the morning.
Best
Source: https://www.livestrong.com/article/298939-how-many-calories-should-i-eat-at-breakfast/
I do believe that you need a lot of energy after long hibernation. But no matter what i think, I eat a lot, cuz I'm a hugry man in the morning.