Estimate your basal metabolic rate (BMR), the calories your body uses at rest, with three well-known equations side by side. The other tabs turn it into an estimate of your daily calorie burn (TDEE) and a daily calorie target for a weight goal.
BMR Formula Comparison
| Formula | BMR (cal/day) | Description | Best For |
|---|
Understanding Your BMR
Basal Metabolic Rate (BMR) is the number of calories your body needs to perform basic life-sustaining functions at rest. This includes breathing, circulation, cell production, and nutrient processing.
- Mifflin-St Jeor: Most accurate for general population (±10% accuracy)
- Harris-Benedict: Traditional formula, slightly overestimates for some
- Katch-McArdle: Most accurate when body fat % is known (lean body mass based)
Select Your Activity Level
Sedentary
Little or no exercise, desk job
BMR × 1.2
Lightly Active
Light exercise 1-3 days/week
BMR × 1.375
Moderately Active
Moderate exercise 3-5 days/week
BMR × 1.55
Very Active
Hard exercise 6-7 days/week
BMR × 1.725
Extra Active
Very hard exercise & physical job
BMR × 1.9
TDEE by Activity Level
Macronutrient Breakdown
| Activity Level | Multiplier | Daily Calories | Weekly Calories |
|---|
Weight Goal Timeline
Projected Weight Progress
Macronutrient Targets for Your Goal
| Meal Timing | Calories | % of Daily Total | Recommended Time |
|---|
Tips for Success
What this BMR calculator does
- Basic BMR: shows your BMR from the Mifflin-St Jeor and revised Harris-Benedict equations, plus Katch-McArdle if you enter a body fat percentage, with a comparison chart and table.
- TDEE Calculator: multiplies your Mifflin-St Jeor BMR by an activity factor from 1.2 (sedentary) to 1.9 (extra active) to estimate total daily energy expenditure, with an example protein, carbohydrate and fat split.
- Calorie Goals: adjusts that figure by 250, 500 or 1,000 calories a day for gradual loss or gain and estimates how long a target weight could take.
The equations used
| Equation | Formula (weight in kg, height in cm, age in years) |
|---|---|
| Mifflin-St Jeor | 10 × weight + 6.25 × height − 5 × age, then +5 for men or −161 for women |
| Harris-Benedict (revised) | Men: 88.362 + 13.397 × weight + 4.799 × height − 5.677 × age. Women: 447.593 + 9.247 × weight + 3.098 × height − 4.330 × age |
| Katch-McArdle | 370 + 21.6 × lean body mass in kg (weight × (1 − body fat %)) |
The Mifflin-St Jeor equation comes from a 1990 study of 498 healthy adults (Mifflin et al., American Journal of Clinical Nutrition). The Harris-Benedict equation was re-evaluated in 1984 (Roza and Shizgal, American Journal of Clinical Nutrition).
Worked example: a 30-year-old man weighing 180 lb (81.6 kg) and 5 ft 10 in (177.8 cm) tall gets about 1,783 calories a day from Mifflin-St Jeor, 1,865 from Harris-Benedict, and 1,781 from Katch-McArdle at 20% body fat. With a moderately active factor of 1.55, his estimated TDEE is about 2,763 calories.
Things to keep in mind
BMR equations give estimates for the average person, and individual metabolism varies. The activity factors, macro splits and weekly rates are common rules of thumb, not a personal prescription. This calculator is for general information only and is not medical advice. If you have questions about your result, talk with your health care provider.
Frequently asked questions
What is the difference between BMR and TDEE?
BMR is the energy your body uses at complete rest. TDEE adds the energy you use moving around and exercising, so it is higher. This calculator estimates TDEE as BMR multiplied by an activity factor.
Which equation should I trust?
They usually land within a few hundred calories of each other. The Katch-McArdle result is only as good as the body fat percentage you give it.
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