Your basal metabolic rate (BMR) is the minimum amount of energy your body burns just to stay alive while lying completely still and doing nothing. It powers your heartbeat, breathing, body temperature, and cellular activity, and accounts for roughly 60-70% of your total daily calorie burn. Add the energy you spend on daily activity and exercise and you get your total daily energy expenditure (TDEE) - the benchmark for how many calories you can eat in a day without gaining weight. This calculator takes your sex, age, height, weight, and activity level and computes your BMR and TDEE at once, then suggests recommended calories for losing and gaining weight.
The calculation uses the Mifflin-St Jeor formula, currently considered the most accurate. For men it is (10 x weight in kg + 6.25 x height in cm - 5 x age + 5); for women the last term is replaced with -161. This is then multiplied by an activity factor (1.2 to 1.9) to find TDEE. To lose weight, the tool recommends eating about 500 kcal below your TDEE (a pace of about 0.5 kg per week); to gain, about 300 kcal more. All of your inputs are processed entirely in your browser and never sent anywhere.
How to Use
- 1
Choose your sex
Select male or female. Basal metabolic rate differs by sex.
- 2
Enter your body details
Enter your age in years, height in cm, and weight in kg.
- 3
Pick your activity level
Choose the one of five levels closest to your usual exercise and activity.
- 4
Review and copy the result
Your BMR and TDEE are shown along with recommended calories for cutting, maintaining, and bulking. Use the copy button to save the result.
When It's Useful
Set diet calories
Use the weight-loss recommendation (TDEE - 500 kcal) as your daily intake target when planning a diet.
Plan a bulk or weight gain
When you want to build muscle, use the weight-gain recommendation (TDEE + 300 kcal) as a guide for your intake.
Maintain your weight
Find out how many kcal a day (TDEE) you need to eat to hold your current weight.
Check a plateau
When your weight loss stalls, recalculate to set a new target calorie level that fits your reduced weight.
Tips
- It is easy to overestimate your activity level. If you hit the gym but sit for the rest of the day, picking one level below 'moderately active' is more realistic.
- Even when cutting, do not let your intake drop too far below your BMR. Excessive restriction leads to muscle loss and a slower metabolism.
- As you build muscle, your BMR rises, so you gain less weight from the same meals. Combining diet with strength training is effective.
- When your weight changes, so do your BMR and TDEE. Recalculate every 2-4 weeks to adjust your target calories.
- Activity factors range over five levels, from sedentary (1.2) to extra active (1.9). When torn between two levels, choosing the lower one helps avoid overeating.
- TDEE is an average estimate, so your weight can change differently day to day on the same diet. Judge by the 1-2 week average trend rather than a single day's number.
FAQ
What is the difference between BMR and TDEE?
BMR is the minimum energy needed to keep you alive, while TDEE adds the energy spent on daily activity and exercise to give your total daily calorie burn. TDEE is the benchmark for diet planning.
Why use the Mifflin-St Jeor formula?
Among the various BMR formulas, it is known to match modern measured values most closely, so it is widely recommended. It has less error than the Harris-Benedict formula.
What exactly is the BMR formula?
For men: 10 x weight (kg) + 6.25 x height (cm) - 5 x age + 5. For women, use -161 instead of the final +5. Multiplying this by an activity factor (1.2 to 1.9) gives TDEE.
How much less should I eat when dieting?
Cutting about 500 kcal a day from your TDEE is expected to lose roughly 0.5 kg per week. That is the basis of this calculator's weight-loss recommendation. Just be sure your intake does not fall below your BMR.
How is the weight-gain recommendation derived?
It suggests a small calorie surplus for building muscle, adding about 300 kcal to your TDEE. An excessive surplus tends to be stored as body fat.
Why are the results different for men and women?
Even at the same height, weight, and age, the formula's final constant differs (+5 for men, -161 for women), so men's BMR generally comes out higher.
Are the calculator's results accurate?
They are formula-based estimates and can differ from your actual metabolic rate by around 10%. Because body composition, hormones, and genetics all play a role, use them as a reference only.
Is the information I enter saved?
No. All calculations happen inside your browser, and your inputs are never sent to or stored on a server.