If You're 6'5" at 20, How Tall Will You Be?
Estimated adult height based on CDC growth trajectory data. Results shown for both sexes — scroll down for the full breakdown.
6'5" at 20 is well above average for boys at 20 (roughly 90th–95th percentile).
6'5" at 20 is well above average for girls at 20 (roughly 90th–95th percentile).
These estimates use CDC 50th-percentile growth trajectory data. Individual results vary based on genetics, puberty timing, and nutrition. ±2 inches for ~80% of individuals.
How much more will you grow at 20?
Boys at age 20 have essentially reached their adult height.
Girls at age 20 have essentially reached their adult height.
How we calculated this.
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 20, we estimate how many inches of growth remain for a typical person of that height and age.
For someone who is 6'5" at age 20: 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 6'5" at 20 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 20 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.
Want a more accurate prediction?
Khamis-Roche Calculator
Add your parents' heights to the prediction. The same method pediatric endocrinologists use — much more accurate than age alone.
Growth Plate Status Quiz
Find out if you're still growing. This quiz estimates your growth plate closure stage based on age, puberty signs, and recent growth velocity.
Related height predictions.
Questions about height at 20.
Can you still grow at 20?
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If I'm 6'5" at 20, is that my permanent height?
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What's the average adult male and female height?
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Browse all height predictions by age → Will I Be Tall? Index