How many calories in a hardboiled egg? A hardboiled egg is a healthy addition to any diet and contains around 70 calories. Hardboiled eggs contain 6grams of proteins that can be easily digested along with a healthy source of vitamins and minerals that make it an energy boosting snack. It contains vitamin B12, vitamin B5, vitamin D iron, sodium, calcium, phosphorous and potassium. A plain hardboiled egg has the same calorie of a raw egg since there is no addition of oil or cream.