BMR Reference for Age 23
Basal metabolic rate at age 23 is not one number — it is a range set by height and weight. This page holds the formula inputs steady at age 23 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 23 returns 1750 kcal, 5 kcal below the 22-year figure of 1755. Harris-Benedict lands 74 kcal above Mifflin (4.2%), and moving from sedentary to extra active multiplies the same estimate out to 3,325 kcal — a 1,225 kcal swing next to the 310 kcal the age term costs between 18 and 80.
BMR at age 23 by body composition
| BMI | Men (175 cm) | Women (165 cm) | ||||
|---|---|---|---|---|---|---|
| Weight | Mifflin | Harris | Weight | Mifflin | Harris | |
| 20 | 61.3 kg | 1597 kcal | 1619 kcal | 54.5 kg | 1300 kcal | 1363 kcal |
| 25 | 76.6 kg | 1750 kcal | 1824 kcal | 68.1 kg | 1436 kcal | 1489 kcal |
| 30 | 91.9 kg | 1903 kcal | 2029 kcal | 81.7 kg | 1572 kcal | 1615 kcal |
| 35 | 107.2 kg | 2056 kcal | 2234 kcal | 95.3 kg | 1708 kcal | 1740 kcal |
From BMR to daily burn: TDEE at age 23
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 1750 kcal):
| Activity level | Factor | TDEE |
|---|---|---|
| Sedentary — little or no exercise | ×1.2 | 2100 kcal/day |
| Lightly active — 1–3 days/week | ×1.375 | 2406 kcal/day |
| Moderately active — 3–5 days/week | ×1.55 | 2713 kcal/day |
| Very active — 6–7 days/week | ×1.725 | 3019 kcal/day |
| Extra active — intense daily training | ×1.9 | 3325 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 23-year-old?
It depends on body size as well as age. At age 23, a 175 cm man weighing about 76.6 kg has a Mifflin-St Jeor BMR of roughly 1750 kcal per day, while a 165 cm woman at 68.1 kg lands near 1436 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.