BMR Reference for Age 38
Basal metabolic rate at age 38 is not one number — it is a range set by height and weight. This page holds the formula inputs steady at age 38 and sweeps body composition instead: four BMI levels, men at 175 cm and women at 165 cm, each estimated with both Mifflin-St Jeor and Harris-Benedict so the spread between the classic equations is visible at a glance.
Read the BMI-25 row as a worked example: 76.6 kg at age 38 returns 1675 kcal, 5 kcal below the 37-year figure of 1680. Harris-Benedict lands 64 kcal above Mifflin (3.8%), and moving from sedentary to extra active multiplies the same estimate out to 3,183 kcal — a 1,173 kcal swing next to the 310 kcal the age term costs between 18 and 80.
BMR at age 38 by body composition
| BMI | Men (175 cm) | Women (165 cm) | ||||
|---|---|---|---|---|---|---|
| Weight | Mifflin | Harris | Weight | Mifflin | Harris | |
| 20 | 61.3 kg | 1522 kcal | 1534 kcal | 54.5 kg | 1225 kcal | 1298 kcal |
| 25 | 76.6 kg | 1675 kcal | 1739 kcal | 68.1 kg | 1361 kcal | 1424 kcal |
| 30 | 91.9 kg | 1828 kcal | 1944 kcal | 81.7 kg | 1497 kcal | 1550 kcal |
| 35 | 107.2 kg | 1981 kcal | 2149 kcal | 95.3 kg | 1633 kcal | 1675 kcal |
From BMR to daily burn: TDEE at age 38
Multiplying BMR by an activity factor gives total daily energy expenditure. The factors below are the same five levels the main calculator offers, applied to the BMI-25 man from the table (76.6 kg, BMR 1675 kcal):
| Activity level | Factor | TDEE |
|---|---|---|
| Sedentary — little or no exercise | ×1.2 | 2010 kcal/day |
| Lightly active — 1–3 days/week | ×1.375 | 2303 kcal/day |
| Moderately active — 3–5 days/week | ×1.55 | 2596 kcal/day |
| Very active — 6–7 days/week | ×1.725 | 2889 kcal/day |
| Extra active — intense daily training | ×1.9 | 3183 kcal/day |
Get your own figure
Body size matters more than any reference table can capture, so a two-minute personal estimate is usually worth more than a row of averages. Enter your numbers and the box computes the Mifflin-St Jeor result with the same coefficients used across this site:
Frequently asked questions
What is the BMR of a 38-year-old?
It depends on body size as well as age. At age 38, a 175 cm man weighing about 76.6 kg has a Mifflin-St Jeor BMR of roughly 1675 kcal per day, while a 165 cm woman at 68.1 kg lands near 1361 kcal per day. The table above shows how the estimate moves across four common body-composition levels.
Why does BMR fall as age increases?
The Mifflin-St Jeor equation subtracts 5 kcal for every year of age, so between age 20 and age 80 the estimate drops by about 300 kcal per day at the same height and weight. The coefficient is a population average: body composition, not the birthday itself, drives most of the real change.
Mifflin-St Jeor or Harris-Benedict — which should I use?
Mifflin-St Jeor is the default on this site because validation studies found it tracks measured resting energy expenditure more closely for most adults. Harris-Benedict, shown beside it in the table, runs higher for many people — often by 5 to 10 percent — so comparing the two columns is a quick way to see the uncertainty band around any single number.
Nearby ages
Want the full picture — Katch-McArdle from body-fat percentage, the age chart and TDEE in one run? Open the BMRScope calculator or browse every age page.