Calculate your Basal Metabolic Rate and daily calorie needs.
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Calculate Your BMR
BMR is calories your body burns at rest.
BMR
cal/day at rest
TDEE
cal/day total
What is BMR?
Basal Metabolic Rate (BMR) is calories needed for basic functions like breathing and circulation at rest. It accounts for 60-75% of daily calorie burn.
Basal Metabolic Rate (BMR) is the number of calories your body burns at complete rest simply to stay alive: breathing, circulating blood, maintaining temperature, repairing cells and running your brain. It accounts for roughly 60 to 70 percent of most people's total daily energy use. BMR is the floor of your metabolism, the figure everything else is added on top of.
How to Use This BMR Calculator
Enter age, sex, height and weight.These four inputs drive the standard equations. Accuracy matters more here than in most calculators, since small input errors shift the result.
Read your BMR.This is your resting energy requirement in calories per day.
Multiply by an activity factor for TDEE.BMR alone is not what you burn in a day. Use the activity table below to reach a realistic daily figure.
The Mifflin-St Jeor Equation
Published in 1990, this is the equation most dietitians use because it validated better against measured values than its predecessors.
Men: BMR = (10 x weight kg) + (6.25 x height cm) - (5 x age) + 5 Women: BMR = (10 x weight kg) + (6.25 x height cm) - (5 x age) - 161
Worked Example
A 32-year-old woman, 165 cm tall, weighing 62 kg
Step 1: Apply the Mifflin-St Jeor equation
(10 x 62) = 620
(6.25 x 165) = 1,031.25
(5 x 32) = 160
BMR = 620 + 1,031.25 - 160 - 161
BMR = 1,330 calories per day
Step 2: Convert BMR to TDEE for a moderately active person
TDEE = 1,330 x 1.55 = 2,062 calories per day
BMR is about 1,330 calories; total daily need is roughly 2,060 at moderate activity
Turning BMR Into TDEE
BMR is what you would burn lying still all day. Real life adds movement, work, exercise and digestion. Multiply by the factor that matches your actual week, not the week you intend to have.
Activity Level
Multiplier
Description
Sedentary
1.2
Desk job, little or no exercise
Lightly active
1.375
Light exercise 1 to 3 days a week
Moderately active
1.55
Moderate exercise 3 to 5 days a week
Very active
1.725
Hard exercise 6 to 7 days a week
Extra active
1.9
Physical job plus daily training
Most people overestimate their activity level
Choosing "very active" when your week is really three gym sessions and a desk job can inflate your calculated needs by several hundred calories a day. If you are unsure between two levels, the lower one is usually closer to reality.
Comparing the Three Main Equations
Equation
Year
Notes
Mifflin-St Jeor
1990
Current standard; best general accuracy
Harris-Benedict
1919, revised 1984
Older; tends to overestimate slightly
Katch-McArdle
1996
Uses lean body mass; best if body fat is known
The Katch-McArdle formula works from lean mass rather than total weight, which makes it more accurate for lean, muscular individuals. It requires a reliable body fat measurement, which most people do not have, so Mifflin-St Jeor remains the practical default.
What Actually Changes Your BMR
Lean muscle mass. The largest modifiable factor. Muscle tissue burns more energy at rest than fat tissue.
Body size. A larger body requires more energy to maintain, which is why weight appears in every equation.
Age. BMR declines gradually through adulthood, largely tracking muscle loss rather than age itself.
Sex. Men typically have higher BMR at the same weight because of greater average lean mass.
Predictive equations typically fall within about 10 percent of measured values, meaning a calculated 1,600 calories could genuinely be anywhere from 1,440 to 1,760. Actual measurement requires indirect calorimetry in a clinical setting. Use the calculated figure as a starting point and adjust based on what you observe over several weeks.
Using BMR Sensibly
BMR is a reference point for understanding your energy needs, not a target to eat at. Any structured change to your intake, particularly a sustained deficit, is better planned with a doctor or registered dietitian who can account for your medical history, medications and circumstances.
If you are tracking energy needs for general fitness, calculate your TDEE, use it as a starting estimate, and adjust gradually based on real-world results over three to four weeks rather than day-to-day fluctuations.
People Also Ask
BMR is the energy your body uses at complete rest to run essential functions such as breathing, circulation and cell repair. TDEE, total daily energy expenditure, is BMR plus everything else: moving, working, exercising and digesting food. TDEE is always higher, typically 1.2 to 1.9 times your BMR depending on how active you are.
The Mifflin-St Jeor equation is generally regarded as the most accurate for the general population and is the one most dietitians use. The older Harris-Benedict equation tends to overestimate slightly. The Katch-McArdle formula can be more accurate still, but only if you know your body fat percentage, since it works from lean body mass.
BMR falls with age, is lower at smaller body sizes, and is lower with less lean muscle mass. Women typically have lower BMR than men of the same weight because of differences in body composition. Prolonged aggressive dieting can also reduce it, as the body adapts to lower energy availability.
Somewhat, but the effect is modest. Building muscle raises it because lean tissue is more metabolically active than fat, though the gain is often smaller than fitness marketing suggests. Eating adequately rather than restricting severely helps avoid the downward adaptation that comes with prolonged under-eating. There is no supplement that meaningfully raises BMR.
No. Eating at BMR means consuming only the energy needed at complete rest, ignoring everything you do while awake. That is an aggressive deficit for most people and is generally not recommended. Weight management calculations should start from TDEE, and any deficit should be moderate and ideally planned with a qualified professional.
This calculator provides estimates for general information only and is not medical or dietary advice. Predictive equations vary from measured values by around 10 percent. Consult a doctor or registered dietitian before making changes to your diet or energy intake.