🧮
home/
calculators/
health/
bmr calculator

BMR Calculator – Basal Metabolic Rate & TDEE (Mifflin‑St Jeor)

BMR Calculator

The BMR Calculator (Basal Metabolic Rate) estimates the number of calories your body burns at complete rest. This basal metabolic rate calculator uses the Mifflin‑St Jeor equation, considered the most accurate for most people. It also calculates your Total Daily Energy Expenditure (TDEE) based on your activity level. Knowing your BMR and TDEE is essential for weight loss, weight gain, or weight maintenance. Whether you are an athlete, a dieter, or simply curious about your metabolism, this calorie calculator provides a personalised starting point.

Basal Metabolic RateBMR~60‑75% of TDEEActivity15‑30%Thermic~10%TDEE = BMR + Activity + Thermic EffectUse to plan weight loss, gain, or maintenance

BMR Formulas (Mifflin‑St Jeor)

For women: BMR = (10 × weight in kg) + (6.25 × height in cm) − (5 × age) − 161

For men: BMR = (10 × weight in kg) + (6.25 × height in cm) − (5 × age) + 5

TDEE = BMR × activity factor (1.2 to 1.9)

How to Use This BMR Calculator

  1. Select your gender.
  2. Enter your age, weight (kg), and height (cm).
  3. Choose your typical activity level.
  4. Click “Calculate” to see your BMR and TDEE.

Why BMR Matters for Weight Management

Your BMR accounts for 60‑75% of your daily energy expenditure. By knowing your BMR, you can avoid eating too few calories (which can slow metabolism) or too many (which leads to weight gain). Once you have your BMR and TDEE, you can set a calorie target that aligns with your goal: subtract 300‑500 calories for weight loss, add 300‑500 for weight gain, or eat at TDEE for maintenance.

Factors that affect BMR include age (BMR decreases with age), muscle mass (more muscle increases BMR), body size, and genetics. Strength training can raise your BMR by increasing lean muscle mass. This basal metabolic rate calculator gives you a baseline; track changes over time as your body composition improves.

Use this BMR calculator in combination with a food diary to achieve your health goals. Bookmark this calorie calculator and metabolism calculator to check your progress monthly.

The Role of Muscle in BMR

Muscle tissue is metabolically active – it burns more calories at rest than fat tissue. Increasing your muscle mass through resistance training can raise your BMR by 50‑100 calories per pound of muscle gained. This is why combining strength training with calorie control is more effective for long‑term weight management than diet alone.

Activity Level Multipliers & TDEE Caloric Target Table

Activity LevelTDEE MultiplierWeight Loss TargetMuscle Gain Target
Sedentary (desk job, no workout)1.20 x BMRTDEE - 500 kcal (Weight Loss)TDEE + 300 kcal (Lean Gain)
Lightly Active (exercise 1-3 days/wk)1.375 x BMRTDEE - 500 kcal (Weight Loss)TDEE + 300 kcal (Lean Gain)
Moderately Active (exercise 3-5 days/wk)1.55 x BMRTDEE - 500 kcal (Weight Loss)TDEE + 300 kcal (Lean Gain)
Active (hard exercise 6-7 days/wk)1.725 x BMRTDEE - 500 kcal (Weight Loss)TDEE + 300 kcal (Lean Gain)
Very Active (physical job & heavy training)1.90 x BMRTDEE - 500 kcal (Weight Loss)TDEE + 300 kcal (Lean Gain)

Frequently Asked Questions

  • Is Mifflin‑St Jeor better than Harris‑Benedict? Yes, studies show Mifflin‑St Jeor is more accurate for modern, sedentary populations.
  • How often should I recalculate my BMR? Every 5‑10 kg of weight change or every 3‑6 months.
  • Can I use this for athletes? Yes, but athletes may need a higher activity factor and may benefit from a body composition assessment.
  • Does BMR change during pregnancy? Yes, it increases significantly. Pregnant women should consult a doctor.

Bookmark this BMR calculator to use it as your go‑to basal metabolic rate calculator, TDEE calculator, and weight loss calculator.

Step‑by‑Step Manual Example

Female, 30y, 65kg, 165cm, moderate activity:

BMR = (10×65) + (6.25×165) − (5×30) − 161 = 650 + 1031.25 − 150 − 161 = 1370 cal/day

TDEE = 1370 × 1.55 = 2124 cal/day

Frequently Asked Questions about BMR

What is Basal Metabolic Rate (BMR)?
Basal Metabolic Rate (BMR) is the minimum number of calories your body requires to perform basic life-sustaining metabolic functions (like breathing, heart pumping, and cell growth) while at rest.
How is BMR calculated using the Mifflin-St Jeor formula?
For Men: BMR = (10 × weight in kg) + (6.25 × height in cm) - (5 × age) + 5. For Women: BMR = (10 × weight in kg) + (6.25 × height in cm) - (5 × age) - 161.
What is the difference between BMR and TDEE?
BMR is resting calorie burn without any physical activity. TDEE (Total Daily Energy Expenditure) is your total daily calorie burn including exercise, work activity, and digestion.
How many calories should I eat to lose weight based on my BMR?
Calculate your TDEE and create a 300 to 500 calorie daily deficit below your TDEE. This yields a safe, sustainable weight loss of roughly 0.5 kg (1 lb) per week.
Is Mifflin-St Jeor more accurate than Harris-Benedict?
Yes. Clinical studies by the Academy of Nutrition and Dietetics proved Mifflin-St Jeor to be within 10% of measured BMR for most individuals, outperforming older 1919/1984 Harris-Benedict equations.
Does muscle mass increase your BMR?
Yes. Lean muscle tissue is metabolically active, burning roughly 6 kcal/lb (13 kcal/kg) per day at rest, compared to fat tissue which burns only 2 kcal/lb (4.5 kcal/kg) per day.
Why shouldn't I eat below my BMR?
Eating significantly below your BMR causes metabolic adaptation (starvation mode), muscle wasting, fatigue, hormonal disruption, and rapid weight regain.
How often should I recalculate my BMR?
Recalculate your BMR every 5 kg (10 lbs) of weight gain or loss, or whenever your physical activity habits change.