If You're 5'9" at 21, How Tall Will You Be?

This prediction is based on CDC National Health and Nutrition Examination Survey (NHANES) growth chart data — specifically the 50th-percentile height trajectory for boys and girls from ages 10 to 20. By comparing the median adult height (age 20) to the median height at age 21, we estimate how many inches of growth remain for a typical person of that height and age.

For someone who is 5'9" at age 21: we calculate your expected remaining growth (boys: ~0 inches; girls: ~0 inches), add it to your current height, and display the result. A ±2 inch confidence range covers approximately 80% of real-world outcomes.

Important limitation: this estimate does not account for your parents' heights, which influence about 60–80% of adult height variation. A child of two tall parents who is 5'9" at 21 is likely to end up taller than predicted here; a child of shorter parents may end up shorter. For a more accurate prediction, use our full Khamis-Roche calculator — it incorporates parent heights and reduces the error to ±1.7–2.2 inches.

Puberty timing also matters significantly. Early developers at age 21 have already grown through part of their spurt; late developers still have that growth ahead. Our Growth Plate Status quiz can help estimate where you are in your development timeline.