π§βπ¦° Teen BMI Calculator
CDC BMI-for-age percentile for ages 13 to 19.
Screening tool only. Teens: talk to a parent, doctor, or school nurse about your result, not the internet.
Teen BMI only makes sense as a percentile. A 15-year-old girl with a BMI of 23 sits at the 80th percentile, healthy weight; the same BMI in an adult woman would be overweight. This calculator runs your numbers through the CDC's BMI-for-age growth chart, the same reference pediatricians use, and tells you the percentile and the weight category for ages 13 to 19.
How to Use This Calculator
Choose your units and sex, enter your age, height, and weight. You get a BMI, a percentile, and the CDC category in one shot.
Measure height without shoes and weight in light clothes. Morning measurements are the most consistent.
Enter your exact age. At 16 and a half, type 16.5: the CDC parameters shift month by month, so precision helps.
Read your percentile. Below 5th is underweight, 5th to 85th is healthy, 85th to 95th is overweight, 95th plus is obesity.
Do not act on the number alone. If it sits outside the healthy band, bring it to a doctor, school nurse, or parent. For younger kids, use our child BMI percentile calculator.
Why Teens Get Percentiles, Not Adult Cutoffs
Puberty makes adult cutoffs useless for teens. Growth spurts hit at different ages, boys add muscle while girls add essential fat, and a 14-year-old mid-spurt can out-BMI a 17-year-old who has finished growing. The CDC's LMS method handles this by comparing you only to same-age, same-sex peers: the L, M, and S parameters for each month of age come from national survey data, and the z-score formula converts your BMI into a percentile. This page uses the actual published CDC parameters, interpolated between yearly values.
The category lines sit at the 5th, 85th, and 95th percentiles. Notice how wide the healthy band is: the 5th to the 85th percentile all counts as healthy weight. That width exists because normal teen bodies vary enormously, and the chart is a screening net, not a verdict. A percentile near a line, like the 84th or the 6th, deserves a calm conversation with a clinician, not panic.
Worked Example
A 15-year-old girl, 64 inches tall, 135 pounds. BMI = 61.2 kg / (1.626 m)^2 = 23.1. CDC parameters for a 15-year-old girl: L = -2.03, M = 19.88, S = 0.151. z = ((23.1/19.88)^-2.03 - 1) / (-2.03 x 0.151) = 0.84, which is the 79.9th percentile: healthy weight, comfortably inside the band. The same BMI of 23.1 on our adult BMI calculator would read as healthy too, but only by coincidence: for a 13-year-old that same BMI would land near the 90th percentile. Age changes everything, which is the whole point of the chart.
Puberty Scrambles the Numbers (Temporarily)
Early developers often see their percentile spike for a year or two during the growth spurt, then settle as peers catch up. Late developers see the mirror image: a low percentile that normalizes later. Neither pattern is a problem by itself. What doctors watch for is a big, fast move across percentile lines that does not match the teen's development stage, or a percentile that stays outside the healthy band after growth steadies. If you play serious sport, remember BMI cannot see muscle: a linebacker-build teen can read overweight while being very lean, and no chart overrules what a clinician sees.
My honest take for teens reading this directly: one BMI reading is trivia. Bodies change month to month at your age, and a single number cannot capture that. If the result worries you, the right move is showing it to a doctor or school nurse, not searching for diets. And if you are tracking fitness rather than weight, body fat percentage tells you more about composition than BMI ever will.
What to Do With Your Result
Healthy band: keep doing what you are doing. An hour of daily activity, regular meals, water over soda, and 8 to 10 hours of sleep cover nearly everything that matters at this age. Outside the band: loop in an adult and a clinician before changing anything. The evidence for teens favors family-based habit shifts over any kind of restrictive dieting, which can interfere with growth and trigger disordered eating. The percentile is the start of a conversation, and it is a conversation worth having with a professional, not with a search bar.
For informational purposes only, not medical advice. Consult a healthcare professional.
Frequently Asked Questions
What is a healthy BMI for a 16 year old?
There is no single healthy BMI number for a 16-year-old. Healthy means a BMI-for-age percentile between the 5th and 85th on the CDC chart, which covers a wide BMI range that shifts with exact age and sex. Enter your numbers above to get your percentile, which is the number that actually matters.
Is BMI accurate for teenage athletes?
Often not. Teen athletes, especially in strength and contact sports, carry more muscle than the chart assumes, so BMI can label them overweight while their body fat is low. Coaches and sports-medicine doctors know this and look at the athlete, not just the chart. If you train seriously, body fat percentage is the better number to track.
Why is my teen BMI different from adult BMI?
The formula is identical, but the interpretation differs. Adults use fixed cutoffs (18.5, 25, 30). Teens use percentiles against same-age peers because growth and puberty move the goalposts constantly. A teen should never be judged by the adult 25/30 lines.
My percentile jumped from 60th to 85th in a year. Should I worry?
Maybe, maybe not. A jump during a growth spurt can be normal, especially for early developers. A jump without a spurt, or one that keeps climbing, deserves a check-in with the pediatrician, who will look at diet, activity, sleep, and family patterns. Do not start a diet on your own first.
At what age do you switch to adult BMI?
At age 20. The CDC BMI-for-age charts run from 2 to 20, and from 20 onward the adult cutoffs (18.5, 25, 30) apply. Between 18 and 20 the two systems roughly agree for most people, which is a useful sanity check.
Can BMI tell if a teen has an eating disorder?
No, and it should never be used that way. Eating disorders occur at every BMI percentile, including the healthy band. Warning signs are behaviors: skipping meals, rigid food rules, compulsive exercise, and distress about weight. If you notice these in yourself or a friend, talk to a counselor, nurse, or doctor promptly.
Does the teen BMI chart differ for boys and girls?
Yes. The CDC publishes separate LMS tables for boys and girls because puberty timing and body composition differ. This calculator selects the right table from your sex selection automatically.
How often should a teen check BMI?
Yearly at the well-child visit is enough. Checking weekly or monthly at home just manufactures anxiety, because normal teen weight fluctuates with growth, hydration, and meals. Trend across a year is the signal; any single reading is noise.
What percentile is obese for a teenager?
The 95th percentile and above on the CDC BMI-for-age chart. Between the 85th and 95th is overweight. These are screening categories that start a clinical conversation, not diagnoses on their own.
My teen is at the 97th percentile. What happens at the doctor?
Expect a review of growth history, family patterns, diet, activity, sleep, and screen time, plus possibly blood pressure and labs like glucose and lipids. For percentiles at or above the 99th, doctors now use the CDC extended growth charts from 2022, which measure severe obesity more precisely than the old curves.