BMR for Teens — Estimating a Teenager's Rate

There is no widely used basal metabolic rate equation built specifically for teenagers, and the adult standard was fitted on people aged 19 and up. The calculator below runs Mifflin-St Jeor, so for an adolescent read it as an approximation with a known caveat attached:

What it gives for a teenager

A 15-year-old boy at 130 lb and 5 ft 8 in — 59.0 kg and 172.7 cm:

10 × 59 + 6.25 × 172.7 − 5 × 15 + 5 = 590 + 1,079 − 75 + 5 = 1,599 kcal/day

A 15-year-old girl at 120 lb and 5 ft 4 in (54.4 kg, 162.6 cm):

544 + 1,016 − 75 − 161 = 1,324 kcal/day

Both are resting figures only. An active teenager’s total for the day is very substantially higher, because school, sport and general restlessness sit outside the basal component entirely.

The growth cost is smaller than the folklore

Ask why teenagers eat so much and you will be told that growing burns enormous energy. The 2023 Dietary Reference Intakes quantify it, and the numbers are modest. The official estimated energy requirement for ages 3 to 18.99 is the sum of total expenditure plus an age-specific energy cost of growth:

Age band	Energy cost of growth
3 to 8 years	about 15 kcal/day
Boys 9 to 13	about 25 kcal/day
Girls 9 to 13	about 30 kcal/day
14 to 18 years	about 20 kcal/day

Twenty kilocalories a day is a bite of toast. Building new tissue is efficient, and the reason a sixteen-year-old athlete eats like one is almost entirely activity and adult-scale body size — not a separate growth furnace.

That said, the official approach does differ from the adult one in a way this calculator cannot reproduce: it uses sex-specific prediction equations for ages 3 to 18.99, built on age, height, weight and physical activity level, before adding the growth term. The adult equation contains no growth component at all.

What is genuinely different in adolescence

Expenditure per unit of fat-free mass is not constant across life. Measurements spanning ages 8 days to 95 years show it peaking in infancy at roughly 50% above adult values, then declining slowly to adult level by about age 20, staying flat from 20 to 60, and falling after that.

An adolescent, then, sits on the tail end of that decline — still running slightly hotter per unit of lean tissue than they will as an adult, and closing the gap year by year. An equation fitted on 19-to-78-year-olds has no term for that, which is one of two reasons its output for a teenager carries more uncertainty than usual. The second is puberty itself: body composition changes fast during it, and weight and height alone are a poor description of a body mid-transformation.

Why this page will not give diet advice

The most common reason someone searches for a teenager’s basal rate is to set a calorie target. That is where this page stops.

Calorie restriction during adolescence without professional supervision can affect growth and pubertal development, and the age group asking is also the age group most exposed to disordered eating content online. Growth curves — weight and height tracked over time against reference percentiles — say far more about whether a teenager is eating enough than any single estimate on a screen. Anyone worried about a teenager’s weight, eating or growth should be talking to a pediatrician or a registered dietitian.

For the same reason, fasting protocols are not appropriate for adolescents without medical guidance; the metabolism during intermittent fasting page covers what those windows do and do not do. For the adult version of this equation and its accuracy, see the BMR calculator, and for teenage weight status specifically, BMI calculator for teens uses age and sex percentiles rather than adult cutoffs.

This content is informational and does not replace evaluation by a pediatrician or registered dietitian.