How long are blue whales when they are fully grown?

The gestation period is around 10 to 12 months. Females typically give birth to one calf every two to three years at the start of winter. The new born is 2.5 metric tons heavy and is around 7 meters long at birth. He drinks nearly 400 liters of milk every day and gains around 100 kilos of weight almost every day when he grows