Summary:
- The fastest a human can grow is during the first year of life, when babies can grow up to 1 inch (2.5 cm) per month.
- After the first year, growth slows down significantly, with children typically growing about 2-3 inches (5-7.5 cm) per year until they reach puberty.
- During puberty, growth can speed up again, with some teenagers growing as much as 4 inches (10 cm) per year, but this rapid growth phase only lasts a few years.