Mifflin-St Jeor · Basal Metabolic Rate
BMR Calculator
Discover your Basal Metabolic Rate — the calories your body burns at rest. Mifflin-St Jeor formula, optimised for Asian populations. See how your BMR translates to TDEE across all activity levels.
Why BMR Matters for Singaporeans
Singapore's high-stress, sedentary work culture means many adults unknowingly consume far more than their BMR — sometimes without any purposeful exercise to compensate. When your daily intake consistently exceeds your TDEE, the excess is stored as body fat regardless of food quality.
The Singapore HPB dietary guidelines recommend approximately 1,800 kcal/day for moderately active women and 2,200 kcal/day for moderately active men. However, for a sedentary office worker, these figures can overestimate actual needs by 200–400 kcal — enough to gain nearly 10 kg over a year if left unchecked.
Knowing your precise BMR lets you set a calorie target grounded in your biology rather than generic guidelines. It is the starting point for calculating your TDEE and creating a calorie deficit that is tailored to your body weight, height, age, and sex.
The Mifflin-St Jeor Formula
Male
BMR = (10 × weight kg) + (6.25 × height cm) − (5 × age) + 5Female
BMR = (10 × weight kg) + (6.25 × height cm) − (5 × age) − 161Published in 1990 by Mifflin and St Jeor, this equation has been validated in multiple independent studies as the most accurate resting metabolic rate predictor for people of Asian descent — more reliable than the older Harris-Benedict equation from 1919.
From BMR to TDEE — Activity Multipliers
| Activity Level | Multiplier | TDEE Example (BMR = 1,500 kcal) |
|---|---|---|
| Sedentary | × 1.2 | 1,800 kcal |
| Lightly Active | × 1.375 | 2,063 kcal |
| Moderately Active | × 1.55 | 2,325 kcal |
| Active | × 1.725 | 2,588 kcal |
| Very Active | × 1.9 | 2,850 kcal |
How BMR Changes With Age
Age 25
Baseline
Peak muscle mass for most adults
Age 45
−5 to −10%
Gradual decline from muscle loss
Age 65
−15 to −20%
Significant impact without resistance training
Resistance training (lifting weights, bodyweight exercises) is the most effective strategy to slow age-related BMR decline by preserving lean muscle mass. Even 2 sessions per week can significantly offset the metabolic slowdown associated with ageing.
Frequently Asked Questions
What is BMR?
Basal Metabolic Rate (BMR) is the number of calories your body burns at complete rest to sustain essential functions — breathing, circulation, cell production, and temperature regulation. For most adults, BMR accounts for 60–70% of total daily calorie burn.
Is Mifflin-St Jeor accurate for Singaporeans?
Yes. Research shows Mifflin-St Jeor predicts resting energy expenditure more accurately for Asian populations than the older Harris-Benedict equation. A 2011 study found Mifflin-St Jeor had the highest accuracy across diverse ethnic groups, including South-East Asians.
What is the difference between BMR and TDEE?
BMR is the base calories burned at rest. TDEE (Total Daily Energy Expenditure) multiplies BMR by your activity level to estimate total daily calorie burn. Multiply your BMR by 1.2 (sedentary) up to 1.9 (very active) to find your TDEE.
Does BMR decrease with age?
Yes. BMR decreases by approximately 1–2% per decade after age 20, primarily due to age-related muscle loss (sarcopenia). Maintaining muscle mass through resistance training is the most effective way to preserve BMR as you age.