BMR Calculator: What Is Your Basal Metabolic Rate?
Short answer
BMR (basal metabolic rate) is the number of calories your body burns at complete rest just to keep running: breathing, circulation, body temperature and organ function. The Mifflin-St Jeor equation estimates it as 10 × weight in kg + 6.25 × height in cm − 5 × age, plus 5 for men or minus 161 for women.
BMR
1,699 kcal/day
calories burned at complete rest
| Activity level | Calories per day |
|---|---|
| Sedentary (×1.2) | 2,039 |
| Light (×1.375) | 2,336 |
| Moderate (×1.55) | 2,633 |
| Very active (×1.725) | 2,930 |
| Extra active (×1.9) | 3,228 |
A BMR calculator estimates how many calories your body would burn in a day if you did nothing but rest. It is the base layer of your daily energy needs, before any walking, working or training is added on top.
Knowing your BMR helps you understand where your calorie target comes from and why it changes with your size, age and activity. Results are estimates for healthy adults and are not medical advice.
What is BMR?
BMR is the energy your body uses at complete rest, awake and fasted, to keep its basic functions going. For most people it is the largest part of the calories they burn in a day.
- Body size. A heavier and taller body uses more energy at rest, which is why weight and height carry the most weight in the equation.
- Age. The equation subtracts 5 calories for each year of age.
- Sex. At the same size and age, the equation gives men about 166 calories more than women (+5 versus −161).
- Muscle mass. Lean tissue uses more energy at rest than fat tissue. The equation does not see body composition, so very muscular people may have a higher BMR than it predicts.
How to use the BMR calculator
- 1
Choose your sex and enter your age
Both change the result: the equation uses a different constant for men and women and lowers BMR as age goes up.
- 2
Enter your height and weight
Use your current weight, measured in the morning before eating if you can.
- 3
Read your BMR
This is the estimated number of calories you burn per day at rest.
- 4
Check the activity table
The table multiplies your BMR by each activity factor, so you can see how many calories you burn on a normal day at your actual activity level.
How is BMR calculated?
BMR is calculated here with the Mifflin-St Jeor equation, published in 1990 and today one of the most widely used formulas for adults. It replaced the older Harris-Benedict equation in many clinical and fitness settings.
- Men: BMR = 10 × weight (kg) + 6.25 × height (cm) − 5 × age + 5
- Women: BMR = 10 × weight (kg) + 6.25 × height (cm) − 5 × age − 161
Example: a 30-year-old woman, 165 cm and 65 kg, has a BMR of 10 × 65 + 6.25 × 165 − 5 × 30 − 161 ≈ 1,370 calories a day. If you work in pounds and inches, convert first: 1 lb = 0.4536 kg and 1 inch = 2.54 cm.
What is the difference between BMR and TDEE?
BMR is what you burn at rest; TDEE (total daily energy expenditure) is what you burn on a real day, including daily movement, work, training and digesting food. TDEE is BMR multiplied by an activity factor. For the woman in the example above, with a BMR of about 1,370:
- Sedentary (× 1.2): about 1,644 calories a day.
- Lightly active (× 1.375): about 1,884 calories a day.
- Moderately active (× 1.55): about 2,124 calories a day.
- Very active (× 1.725): about 2,364 calories a day.
- Extra active (× 1.9): about 2,603 calories a day.
So BMR is never the number to eat. To maintain weight you eat around your TDEE, and fat-loss or muscle-gain targets are set relative to TDEE, not BMR. To get those targets directly, use the calorie calculator.
How coaches use BMR with clients
Personal trainers and online coaches use BMR mostly to explain the numbers. Showing a client that most of their daily calories go to simply staying alive, and that training adds less than they think, makes a calorie target easier to accept and stick to.
On the Coach+ coaching platform, you set the resulting calorie and macro targets in a client’s meal plan, and clients log food by barcode, photo or search in your own branded app. The AI assistant can draft a meal plan for you to review, and weekly check-ins with weight and progress photos tell you when the numbers need to change.
Frequently asked questions
Is BMR the same as RMR?
They are close but not identical. BMR is measured under strict conditions (fully rested, fasted, in a controlled setting), while RMR (resting metabolic rate) is measured under looser ones and usually comes out slightly higher. Online calculators use the terms almost interchangeably.
Should you eat less than your BMR?
For most people there is no need to. Fat-loss targets are set from TDEE, which is well above BMR for anyone who moves during the day, so a moderate deficit usually stays above BMR.
Does building muscle increase BMR?
Yes, somewhat. Muscle uses more energy at rest than fat, so gaining muscle raises BMR a little, but the Mifflin-St Jeor equation only sees your total weight, not how much of it is muscle.
Why does BMR go down with age?
The equation lowers BMR by 5 calories per year of age. In real life, part of that drop is linked to losing muscle over time, which is one reason strength training matters as people get older.
How do I calculate my BMR by hand?
Multiply your weight in kg by 10, add 6.25 times your height in cm, subtract 5 times your age, then add 5 if you are a man or subtract 161 if you are a woman. A BMR calculator does the same math instantly.
