Your basal metabolic rate, or BMR, is the number of calories your body burns just to keep you alive — powering your breathing, circulating blood, maintaining body temperature and keeping your organs running — while you are completely at rest. It is the single largest slice of your daily calorie burn, typically 60–70% of the total, which makes it the foundation of any sensible eating plan. Whether your goal is losing weight, gaining it, or simply eating enough to fuel your day, everything starts from this baseline number.
This calculator uses the Mifflin-St Jeor equation, the formula most dietitians and researchers prefer today. It estimates BMR from four inputs — age, gender, height and weight — and expresses the result in calories per day. For most Indian adults the figure lands somewhere between 1,200 and 2,000 calories, varying mainly with body size: a taller, heavier person burns more at rest than a shorter, lighter one, and BMR slowly declines with age as muscle mass decreases.
Knowing your BMR replaces guesswork with a starting point. Your total daily needs are higher than BMR once movement and exercise are added — that fuller picture is what our TDEE calculator covers — but BMR itself tells you the floor below which you should rarely eat for long. Consistently eating far below BMR can slow your metabolism, drain energy and cost you muscle, which is why crash diets built on extreme restriction so often backfire.
How it works
The Mifflin-St Jeor equation, published in 1990, is: for men, BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age + 5; for women, BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age − 161. In validation studies it has predicted resting metabolic rate more closely than the older Harris-Benedict formula for most adults, which is why it became the clinical standard. The gender difference reflects body composition: at the same weight, men on average carry more muscle and less fat, and muscle burns more calories at rest than fat does.
Like all formulas, it estimates rather than measures. It cannot see your muscle-to-fat ratio, so it is less precise for very muscular athletes, people with obesity, the elderly, and during pregnancy or illness — groups for whom lab measurement (indirect calorimetry) is the gold standard. For most people it lands within about 10% of the true value, which is plenty close for setting a starting calorie target. The practical method is to start from the estimate, track your weight for two to three weeks, and adjust based on what actually happens.
How to use this tool
- Select your gender, since the formula uses different constants for men and women.
- Enter your age in years.
- Enter your height in centimetres and weight in kilograms.
- Click Calculate to see your estimated BMR in calories per day.
- Use it as your baseline — plan daily intake at or above BMR, adjusted for activity.
- Recalculate after significant weight change, since a lighter body burns less at rest.
Practical tips
- Don't eat below your BMR for extended periods — chronic under-eating slows metabolism and sacrifices muscle.
- Remember BMR is the resting floor, not your daily target; add activity calories (see the TDEE calculator) for real meal planning.
- Strength training is the most reliable way to raise BMR over time, since muscle is metabolically expensive tissue.
- Weigh yourself at the same time each morning for 2–3 weeks and adjust calories based on the trend, not a single day.
Frequently asked questions
What is the Mifflin-St Jeor equation?
It is a formula developed in 1990 that estimates BMR from age, gender, height and weight: 10×weight + 6.25×height − 5×age, plus 5 for men or minus 161 for women. In validation studies it predicted resting metabolic rate more closely than the older Harris-Benedict formula for most adults, which is why dietitians commonly use it today.
Why is BMR different for men and women?
At the same weight, men on average carry more muscle mass and less body fat than women, and muscle burns more calories at rest than fat tissue does. The formula reflects this with different constants. Individual variation is still large, so treat the result as a starting estimate rather than a personal measurement.
Does having more muscle raise my BMR?
Yes. Muscle is metabolically active tissue, so two people of identical weight can have different BMRs depending on body composition. Strength training that builds muscle tends to raise BMR modestly over time. The calculator can't see your muscle-to-fat ratio, so very muscular or very lean people should treat the figure as approximate.
How accurate is a BMR estimate?
Formula-based BMR is usually within about 10% of lab-measured values for typical adults — good enough for setting a starting calorie target. It is less reliable at extremes of weight, for athletes, during pregnancy or illness, and for older adults with significant muscle loss. Adjust based on real weight changes over a few weeks.
Does BMR fall as I get older?
Yes, gradually — roughly 1–2% per decade after early adulthood, mainly because muscle mass declines with age. The formula's age term captures this average decline. Regular strength training and adequate protein can slow the loss considerably, which is one reason active older adults often have higher BMRs than the formula predicts.
Can I use BMR alone to plan weight loss?
Not quite — BMR is only the resting portion. Your total daily burn (TDEE) adds all movement and exercise on top, and that is the number to plan meals around. Eating at BMR with a sedentary lifestyle usually means slow weight gain; a moderate deficit below TDEE, not below BMR, is the sustainable path to fat loss.
Note: This tool is for general information only and is not medical advice. BMR formulas estimate rather than measure — consult a qualified health professional for personalised nutrition or weight-management guidance.