BMR Calculator
HealthCalculate your Basal Metabolic Rate using the Mifflin-St Jeor equation. Know your minimum daily calorie need to maintain basic body functions at rest.
Gender
Age
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Weight
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Height
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BMR (kcal/day)
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BMR (kJ/day)
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Calories per Hour
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What is a BMR?
A BMR Calculator computes your Basal Metabolic Rate — the number of calories your body burns at complete rest just to sustain essential life functions: heartbeat, breathing, body temperature regulation, cell repair, and brain activity. BMR represents the floor of your calorie needs; you would burn this many calories even if you did nothing but lie still all day.
This calculator uses the Mifflin-St Jeor equation, the most accurate and widely used formula for estimating BMR in healthy adults. It was developed in 1990 and validated across diverse populations, making it more reliable than the older Harris-Benedict formula that most calculators still use.
For Indian users, BMR is the essential starting point for:
- Weight loss planning — knowing your calorie floor prevents under-eating
- Muscle gain diets — understanding calorie surplus targets
- Health monitoring — tracking metabolic changes with age or after illness
BMR is not the same as your full daily calorie need — that requires accounting for your physical activity level. Use this result with the TDEE Calculator to find your activity-adjusted daily requirement.
How to use this BMR calculator
- Select your Gender — Male or Female. This changes the constant in the Mifflin formula (+5 for men, −161 for women).
- Enter your Age in years using the slider or input field.
- Enter your Weight in kilograms. Use a digital scale for accuracy; small errors in weight significantly affect the result.
- Enter your Height in centimetres. Convert from feet: multiply feet by 30.48 and add inches × 2.54.
- The BMR result appears instantly in kcal/day — this is your metabolic floor.
- Note the kJ/day result if you're referencing international nutrition guidelines that use kilojoules.
- Take your BMR result to the TDEE Calculator and select your activity level to find your full daily calorie requirement.
Formula & Methodology
Mifflin-St Jeor Equation (1990):Men: BMR = (10 × weight_kg) + (6.25 × height_cm) − (5 × age_years) + 5 Women: BMR = (10 × weight_kg) + (6.25 × height_cm) − (5 × age_years) − 161Worked example — 32-year-old male in Hyderabad, 75 kg, 175 cm:BMR = (10 × 75) + (6.25 × 175) − (5 × 32) + 5 = 750 + 1093.75 − 160 + 5 = 1,688.75 kcal/day ≈ 1,689 kcal/day = 7,067 kJ/day = 70.4 kcal/hourBMR reference table for Indian adults: | Profile | BMR (approx.) | |---|---| | Woman, 25 yrs, 55 kg, 160 cm | 1,334 kcal/day | | Woman, 40 yrs, 65 kg, 162 cm | 1,417 kcal/day | | Man, 25 yrs, 65 kg, 170 cm | 1,659 kcal/day | | Man, 40 yrs, 80 kg, 175 cm | 1,745 kcal/day | | Man, 55 yrs, 75 kg, 172 cm | 1,600 kcal/day | BMR in kJ = BMR in kcal × 4.184. All values are estimates; individual metabolic rates vary by ±10%.
Frequently Asked Questions
What is Basal Metabolic Rate (BMR)?
Basal Metabolic Rate (BMR) is the number of calories your body burns at complete rest — the minimum energy required to keep your heart beating, lungs breathing, brain functioning, and organs running. It accounts for roughly 60–75% of your total daily calorie expenditure. BMR is the starting point for all calorie and diet calculations.
Which formula does this BMR calculator use?
This calculator uses the Mifflin-St Jeor equation, which is considered the most accurate general-purpose BMR formula for the adult population. Published in 1990, it has been validated across diverse populations and is preferred by most dietitians and health organisations over the older Harris-Benedict equation. The formulas are: Men: BMR = (10 × weight in kg) + (6.25 × height in cm) − (5 × age) + 5; Women: BMR = (10 × weight in kg) + (6.25 × height in cm) − (5 × age) − 161.
What is the difference between BMR and TDEE?
BMR is your calorie burn at absolute rest — if you lay still all day without eating or moving, you would burn exactly your BMR. TDEE (Total Daily Energy Expenditure) is your actual daily calorie burn, which includes physical activity on top of BMR. TDEE = BMR × Activity Multiplier. For most active adults, TDEE is 1.4–1.9 × their BMR. Use the TDEE Calculator to compute your full daily calorie need.
What is a normal BMR for an Indian adult?
For Indian adults, BMR typically ranges from 1200–1600 kcal/day for women and 1400–1900 kcal/day for men, depending on height, weight, and age. India's National Institute of Nutrition (NIN) reference body weights (55 kg for women, 65 kg for men) correspond to BMR values around 1350 kcal/day (women) and 1600 kcal/day (men). Individual values vary widely based on body composition.
Does BMR decrease with age?
Yes, BMR decreases with age, primarily because muscle mass tends to decline with age (a process called sarcopenia) while body fat percentage increases. Muscle tissue is more metabolically active than fat, so less muscle means a lower BMR. Research suggests BMR decreases by approximately 1–2% per decade after age 30. This is one reason why gradual weight gain is common in middle age even with similar eating habits.
How does gender affect BMR?
Men typically have a higher BMR than women of the same age, height, and weight — usually by 5–10%. This is primarily because men generally have a higher percentage of lean muscle mass and lower body fat percentage than women. The Mifflin-St Jeor equation accounts for this with the +5 constant for men and −161 constant for women. Hormonal differences, particularly testosterone's muscle-building effects, also contribute.
Can I use my BMR to plan a weight loss diet?
BMR alone is not enough to plan a diet — you need your TDEE (BMR × activity level). Once you know your TDEE, create a calorie deficit: reducing intake by 500 kcal/day below TDEE typically results in approximately 0.5 kg of weight loss per week. Never eat below your BMR for sustained periods; doing so triggers metabolic adaptation where your body reduces its BMR to conserve energy. Use the Calorie Calculator for diet planning.
How do I use the BMR Calculator?
Select your gender, then enter your age in years, weight in kilograms, and height in centimetres. The BMR updates instantly. The result is shown in kcal/day (kilocalories per day) — the standard unit used on food labels in India. Use this BMR as the input to the TDEE Calculator to find your activity-adjusted daily calorie requirement.
What factors lower BMR that the calculator does not account for?
The Mifflin-St Jeor equation estimates BMR from age, gender, height, and weight. It does not account for: thyroid function (hypothyroidism significantly lowers BMR), lean body mass vs. fat mass (a muscular person has a higher BMR than the formula predicts), chronic illness, and medication effects. For clinical purposes, indirect calorimetry (metabolic cart testing) is used for precise measurement. The calculator gives a statistically accurate population estimate.
What is the difference between BMR and RMR?
BMR (Basal Metabolic Rate) and RMR (Resting Metabolic Rate) are often used interchangeably, but technically differ in measurement conditions. BMR is measured after 8+ hours of sleep, 12+ hours fasting, in a thermoneutral environment at complete physical rest. RMR is measured simply at rest, without the strict fasting and sleep requirements, making it slightly higher (2–3%) than BMR. In practice, most online calculators compute RMR while calling it BMR.
How accurate is the BMR Calculator result?
The Mifflin-St Jeor equation predicts BMR within ±10% for most adults. In a 2005 review, it was accurate within 10% for 82% of non-obese and 70% of obese individuals. For the average Indian adult, this means the result could be 130–160 kcal/day higher or lower than your true BMR. This level of accuracy is sufficient for practical diet planning — track your actual weight response over 2–4 weeks and adjust calories accordingly.
How does weight affect BMR in Indian context?
Every kilogram of body weight adds approximately 10 kcal/day to your BMR (from the Mifflin formula). However, the type of weight matters: 1 kg of muscle has higher metabolic activity than 1 kg of fat. Given that Indian adults have higher average body fat percentage at the same BMI compared to Caucasian populations (a phenomenon well-documented in research), the Mifflin formula may slightly overestimate BMR for some Indian individuals. For weight management, pairing BMR with body fat percentage data from the Body Fat Calculator gives a more accurate picture.