The number of calories you should eat per day depends on several factors including your age, sex, activity level, and weight goals (maintain, lose, or gain weight). Here are general guidelines:

• Women typically need about 1,600 to 2,400 calories per day.
• Men typically need about 2,000 to 3,000 calories per day.
• Sedentary individuals require fewer calories; active individuals require more.
• For weight maintenance, you should balance calorie intake with calories burned.
• To lose weight, consume fewer calories than you burn (usually a deficit of about 500 calories per day to lose roughly 1 pound per week).
• To gain weight, consume more calories than you burn, focusing on nutrient-dense foods.

Example calorie needs by activity (for adults 21 and older) according to the Dietary Guidelines for Americans: Women:

• Sedentary: 1,600–2,000 calories
• Moderately active: 1,800–2,200 calories
• Active: 2,000–2,400 calories

Men:

• Sedentary: 2,000–2,400 calories
• Moderately active: 2,200–2,800 calories
• Active: 2,400–3,000 calories

It's important to choose nutrient-rich foods rather than empty calories from junk food, and consider consulting a dietitian for personalized recommendations. In summary, average general recommendations are about 2,000 calories per day for women and 2,500 calories per day for men, but individual needs vary widely based on age, activity, and goals.