Puberty marks the transition from childhood to the physical capability of reproduction, driven by a surge in sex hormones. These hormones initiate physical changes that transform the body over several years. Pinpointing the exact moment puberty ends is complex, as it is not a single, instantaneous event. The completion of puberty is best understood by observing when physical growth stops and when secondary sexual characteristics stabilize, indicating that rapid hormonal changes have subsided.
The Definitive Biological End: Skeletal Maturity
The most definitive sign that physical growth has ceased is the achievement of skeletal maturity, marked by the closure of the epiphyseal plates, or growth plates. These plates are areas of cartilage located near the ends of long bones where bone elongation occurs during childhood and adolescence. As the body is flooded with sex hormones, particularly estrogen and testosterone, a process of senescence is accelerated within the growth plates.
Estrogen, whether produced directly or converted from testosterone in those assigned male at birth, plays a central part in this fusion process. This hormone hastens the exhaustion of the cartilage cells’ ability to proliferate and differentiate, causing the growth plate to narrow. Eventually, the cartilage is completely replaced by solid bone, a process called epiphyseal fusion, which halts all further linear growth in height.
For those assigned female at birth, this fusion typically occurs around ages 14 to 16, while for those assigned male at birth, it happens slightly later, generally between ages 16 and 19. The timing of this internal event often precedes the full stabilization of external, secondary sex characteristics. Once these plates are fused, the individual has reached their maximum adult height, providing a clear biological marker for the end of the body’s growth phase.
Observable Physical Milestones in Those Assigned Male at Birth
The end of puberty in individuals assigned male at birth is recognized by the stabilization of several external characteristics, signifying the completion of Tanner Stage 5 of physical maturation. The growth of the genitals reaches its final adult size and form, typically around age 15. Muscle development may continue for a few years longer, even after genital growth has ceased.
The voice achieves its permanent, deeper pitch, as the “cracking” phase ends. Facial hair begins to fully establish its adult pattern, often requiring regular shaving, and body hair fills out. The development of mature muscle mass and the final distribution of body fat, typically favoring the shoulders and chest, becomes established.
Observable Physical Milestones in Those Assigned Female at Birth
For individuals assigned female at birth, the physical end of puberty is defined by the completion of secondary sexual characteristics, aligning with Tanner Stage 5. Breast development reaches its approximate adult size and shape, though minor changes can continue past this stage. The distribution of body fat shifts to the adult pattern, particularly around the hips and thighs.
The establishment of a regular, predictable menstrual cycle is the primary sign of hormonal completion. While the first period, or menarche, happens relatively early in puberty, it can take six months to two years for the cycle to become consistently regulated, indicating a stable, mature hormonal system.
Beyond Physical Change: Hormonal and Cognitive Stabilization
While the physical process of puberty ends, overall maturation continues for many years. Hormonal levels that initiated the rapid changes begin to stabilize, contributing to fewer mood fluctuations that characterize early adolescence. Although the physical body has reached adulthood, the systems that regulate emotion and decision-making are still developing.
Brain development, particularly in the prefrontal cortex, extends well past the cessation of physical growth. This area is responsible for executive functions, including complex planning, impulse control, and judgment. Neural remodeling in this region, which involves the pruning of synapses and the myelination of white matter, is influenced by pubertal hormones. These changes continue throughout the late teens and early twenties, with some research suggesting that the brain’s architecture may not fully stabilize until around age 32.