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BMR calculator: the energy your body uses at rest
This free calculator estimates your basal metabolic rate (BMR) — the energy your body uses at complete rest — from your age, sex, height and weight, using the Mifflin-St Jeor equation. NNWA presents the result as resting energy expenditure in kilocalories per day; it is a baseline for planning, not an eating target.
Your basal metabolic rate is the energy your body spends at complete rest — keeping the heart beating, the lungs filling, the brain working, cells repairing themselves. It is the largest share of what most people burn in a day, and it runs whether you exercise or not. Enter your age, sex, height in centimetres and weight in kilograms, and this calculator estimates that resting figure in kilocalories per day.
The calculation uses the Mifflin-St Jeor equation, the formula most widely recommended for estimating resting energy in adults. In India, where conversations about weight and diet often begin with borrowed numbers — a plan copied from a friend, a target lifted from an app — knowing your own baseline matters. It anchors everything that follows: a sensible calorie target, a realistic rate of change, a diet built around your food rather than someone else's.
Basal metabolic rate — Mifflin-St Jeor
Resting rate
1,350kcal/day
The energy your body spends at complete rest — before a single step is taken or a meal is digested.
10 × weight (kg) + 6.25 × height (cm) − 5 × age + (−161)
The resting rate is not an eating target — almost nobody should eat at BMR. Multiply by an activity factor for the day's true expenditure, or use the TDEE calculator, which does exactly that.
How practitioners use the resting rate01What basal metabolic rate actually is
BMR is the energy your body uses at complete rest, awake but doing nothing — no digestion in progress, no movement, a comfortable room. It covers the invisible work of staying alive: circulation, breathing, brain activity, maintaining body temperature, building and repairing tissue. For most people it accounts for the largest portion of daily energy use, more than exercise does.
Strictly speaking, laboratories measure BMR under tight fasting and rest conditions; what equations like this one estimate is closer to resting energy expenditure, a slightly less strict cousin. For everyday planning the distinction rarely matters, which is why the two terms travel together.
02The exact formula behind the result
This calculator uses the Mifflin-St Jeor equation. It takes your weight in kilograms, your height in centimetres and your age in years, then computes: 10 × weight + 6.25 × height − 5 × age, plus 5 for men or minus 161 for women. The output is resting energy expenditure in kilocalories per day.
Nothing else feeds the number — no activity level, no body-fat estimate, no adjustment for climate or cuisine. That simplicity is deliberate: the equation asks only for measurements you can take reliably at home, and it behaves predictably across the adult range of heights and weights.
03Why Mifflin-St Jeor, and the limits of any equation
The Harris-Benedict equation, published in 1919, held the field for decades, but it was built on a small early-twentieth-century sample and tends to overestimate resting energy for many adults today. Mifflin-St Jeor was derived later, validated on modern populations, and carries a smaller average error — which is why it has become the standard choice for adults and the one this calculator uses.
The Katch-McArdle formula takes a different route, working from lean body mass, and can suit very muscular people better. But it needs a body-fat percentage, and most people do not have a reliable one. A guessed body-fat figure fed into a precise formula produces a precise-looking wrong answer. Mifflin-St Jeor asks only for what you actually know.
Any prediction equation describes an average body, not yours. Two people with identical age, height and weight can differ meaningfully in resting energy, because the formula cannot see body composition, hormonal health, pregnancy or the adaptation that follows hard dieting, and it was not built for children. Expect the true figure to sit somewhat above or below the estimate, and treat it as a starting point rather than a verdict.
04A baseline, not an eating target
Do not eat to your BMR. The figure describes a body at complete rest, and you do not live at complete rest — you commute, cook, climb stairs, digest, fidget. Your true daily requirement is BMR multiplied by an activity factor, which the TDEE calculator works out for you.
Eating at or below BMR for long stretches is a common self-inflicted mistake: energy drops, meals become joyless, and the deficit rarely holds. If your goal is weight change, start from the day total and set a moderate deficit or surplus — the calorie calculator covers that step.
05What a trained practitioner does with this number
For a nutrition counsellor, BMR is the first line of a longer calculation, not the conclusion. A practitioner estimates the day's total requirement, sets a target that fits the client's goal, then translates it into actual meals — dal, rice, roti, vegetables, portions that survive a festival week. They also know when the equation misleads: for the very muscular, the elderly, or someone with a thyroid condition, the estimate needs professional judgement around it.
That movement from a formula to a workable plan is what NNWA teaches. The Diploma in Nutrition builds the full method from first principles, and the weight management course applies it to fat loss specifically.
This calculator gives a screening estimate, not a diagnosis or a prescription. If you have a medical condition, are pregnant, or are planning a significant change in diet, speak to a doctor or a qualified nutrition professional before acting on the number.
What people ask about the BMR calculator
Expand any question to read the answer in full.
What is a normal BMR?
There is no single normal figure. BMR scales with body size, so a taller, heavier person burns more at rest than a smaller one, and it declines gradually with age. Men typically show higher values than women of the same size because of greater lean mass. Rather than comparing your number with anyone else's, use it as your own baseline for planning.
Should I eat as many calories as my BMR?
No. BMR describes energy use at complete rest, and your day involves far more than rest — movement, digestion, work, exercise. Your actual requirement is BMR multiplied by an activity factor, which NNWA's TDEE calculator estimates. Even for weight loss, sensible plans usually set intake between BMR and total daily expenditure, not at or below the resting figure.
Why does the formula subtract 161 for women?
Women typically carry a higher proportion of body fat and less lean mass than men of the same height and weight, and lean tissue burns more energy at rest. The constants — plus 5 for men, minus 161 for women — were fitted from measured data so the equation tracks that average difference. They are statistical adjustments, not judgements about any individual body.
How accurate is the Mifflin-St Jeor equation?
For most adults it lands close enough to be useful for planning, with a smaller average error than the older Harris-Benedict equation. It is still an estimate built on population averages: very muscular, very lean or older people, and anyone with a thyroid or other metabolic condition, can sit outside its range. Treat the result as a starting point you adjust against real progress.
Can I increase my BMR?
Modestly, and slowly. The most reliable lever is building muscle, because lean tissue uses more energy at rest than fat does. Crash dieting works the other way: prolonged very-low-calorie eating pushes the body to conserve energy, lowering resting expenditure. Adequate protein, resistance training and patience raise the baseline; no food or supplement meaningfully boosts metabolism.
Is BMR the same as resting metabolic rate?
Nearly. BMR is measured under strict laboratory conditions — fasted, fully rested, in a controlled environment — while resting metabolic rate is measured under looser conditions and runs slightly higher. Prediction equations such as Mifflin-St Jeor were built against resting measurements, so this calculator's output is best read as resting energy expenditure. For everyday diet planning, the difference is too small to matter.
Turn the arithmetic into a skill
A figure is the first five minutes of a consultation. These programmes teach what a practitioner does with it.
Diploma in Nutrition
Learn how practitioners turn estimates like BMR into complete, food-first nutrition plans.
Weight management course
Every credible weight plan starts from a resting baseline; this course teaches the rest of the method.
Sports nutrition course
Athletes' energy needs stretch prediction equations to their limits; learn to fuel high training loads properly.
A figure is not a diet plan
Turning a screening number into a chart someone will actually follow — for their condition, their kitchen and their budget — is the skill the Diploma teaches.