On average, a person gains about 3 inches in height after their first period (menarche).
According to the provided reference, the average height gain after menarche is about 7 cm, which is approximately 3 inches. It also indicates that individuals who start menstruating earlier in the normal range may experience even greater height gains. While it's a common myth that growth stops after menarche, this isn't entirely true. Some growth still occurs, but it's typically limited.
