BMI Calculator for Teens

What this Bmi Teens Calculator does

Adult BMI cutoffs — underweight below 18.5, overweight above 25 — don't apply to children and adolescents. Pediatric body mass index for teens is always interpreted against CDC age- and sex-specific percentile growth charts, because body fat changes naturally as kids grow, and differs between teenage females and teenage guys at every age. This English-language version of the calculator takes a teen's age, sex, height, and weight, computes their BMI, then maps the result to a CDC percentile category: underweight (below 5th percentile), healthy weight (5th–84th), overweight (85th–94th), or obese (95th and above). Importantly, Adolphe Quetelet designed the BMI formula in the 1830s as a population-level statistic, not an individual diagnostic — a distinction the IRS and clinical guidelines both honor when using BMI only as a flag for further screening. 100% client-side — your data never leaves your browser. No uploads, no tracking, no server logs.

Features

• CDC percentile growth charts. Maps every result to the official CDC age- and sex-specific percentile bands used by U.S. pediatricians, so a teenager's BMI is read in the right clinical context.
• Separate charts for girls and guys. Uses distinct growth curves for teenage females and teenage guys, because body composition trajectories diverge significantly during adolescence.
• Supports both unit systems. Enter height and weight in pounds and inches or kilograms and centimeters — the calculator handles both without you switching modes.
• Instant, privacy-first results. All math runs locally in your browser via plain JavaScript. No form submission, no server round-trip, no account required — results appear in milliseconds.
• Readable category output. Displays the numeric BMI, the percentile range, and the weight-status category in plain language so results are easy to understand and share with a clinician.
• Complements a full health picture. For a broader view of adolescent nutrition targets, the [TDEE calculator](/en/tdee-calculator/) estimates daily energy needs, and the [Body Fat Percentage Calculator](/en/body-fat-percentage-calculator/) adds lean-mass context that raw BMI can't provide.

How to use the Bmi Teens Calculator

Enter the teen's details, click Calculate, and read the percentile category in the result panel. The whole process takes under 30 seconds.

1. Select sex. Choose male or female — the calculator loads the correct CDC growth curve for that sex before doing any math.
2. Enter age. Type the age in years and months (e.g., 15 years, 4 months). Percentile bands shift noticeably across each six-month interval, so precision matters.
3. Enter height and weight. Input height and weight in your preferred units. For example: height: 5ft 7in, weight: 145 lb or 170 cm, 66 kg.
4. Click Calculate. The tool computes BMI as weight(kg) / height(m)², looks up the age- and sex-specific percentile, and displays the weight-status category instantly.
5. Review and share. Use the Copy button to grab the result text for a health log, school form, or follow-up appointment with a pediatrician or dietitian.

Common use cases

• Annual well-child visit prep. Parents in Boston and New York often track a teen's BMI trend year over year before a pediatric appointment. Running the calculator at home gives families context before the conversation with the doctor.
• School health screening. School nurses conducting BMI tests for teenagers can use this tool for quick lookups without installing software or sending data to an external service.
• Adolescent nutrition coaching. Registered dietitians working with teenage clients use body mass index for teens alongside a weight chart to set realistic, age-appropriate goals rather than applying adult cutoffs.
• Physical education programs. PE teachers or coaches tracking fitness metrics for a team can compute the BMI index for teens quickly during class without needing a dedicated app or internet-connected device.
• Personal health journeys. Teens or young adults revisiting childhood health history — including those who have managed weight since early childhood — can use this tool to understand where their BMI percentile stood at different ages.

Frequently asked questions