BMR Calculator | Daily Calories & TDEE Estimate
Estimate your basal metabolic rate, daily calorie needs, and goal-based calorie targets with clear formulas, step-by-step work, activity-level adjustments, and helpful visuals.
Background
Basal metabolic rate, or BMR, is the estimated number of calories your body burns at rest to support essential functions such as breathing, circulation, body temperature, and cell repair. This calculator can also estimate TDEE, which adjusts BMR by activity level to approximate your total daily calorie needs.
How to use this BMR calculator
- Enter your age, sex used in the formula, height, and weight.
- Choose Metric or US units.
- Select a formula, or use Mifflin-St Jeor as the default.
- Choose your activity level to estimate TDEE, or total daily energy expenditure.
- Pick a goal to estimate daily calories for maintenance, weight loss, or weight gain.
How this calculator works
- First, it converts height and weight into centimeters and kilograms if needed.
- Then it estimates BMR using the selected equation.
- Next, it multiplies BMR by your activity factor to estimate TDEE.
- Finally, it adjusts TDEE up or down based on your selected goal.
Formula & Equations Used
Mifflin-St Jeor, male: BMR = 10w + 6.25h − 5a + 5
Mifflin-St Jeor, female: BMR = 10w + 6.25h − 5a − 161
TDEE: TDEE = BMR × activity factor
In these formulas, w is weight in kilograms, h is height in centimeters, and a is age in years.
Example Problem & Step-by-Step Solution
Example 1 — Estimate BMR and daily calories
- Suppose a 22-year-old male is 70 kg and 175 cm tall.
- Use Mifflin-St Jeor: BMR = 10(70) + 6.25(175) − 5(22) + 5.
- Calculate: 700 + 1093.75 − 110 + 5 = 1688.75.
- The estimated BMR is about 1,690 calories/day.
- If lightly active, multiply by 1.375: TDEE is about 2,320 calories/day.
Example 2 — Estimate daily calories for weight loss
- Suppose estimated TDEE is 2,320 calories/day.
- For mild weight loss, subtract about 250 calories.
- 2,320 − 250 = 2,070.
- The mild weight-loss target is about 2,070 calories/day.
Example 3 — Use Katch-McArdle with body fat percentage
- Suppose someone weighs 80 kg and has 18% body fat.
- Lean body mass is 80 × (1 − 0.18) = 65.6 kg.
- Use Katch-McArdle: BMR = 370 + 21.6(65.6).
- The estimated BMR is about 1,787 calories/day.
Common mistakes with BMR estimates
- Confusing BMR with TDEE. BMR is resting energy; TDEE includes activity.
- Choosing an activity level that is too high.
- Treating calorie estimates as exact instead of approximate.
- Using Katch-McArdle without a reasonable body fat percentage estimate.
- Making aggressive calorie changes without considering health, energy, and sustainability.
FAQs
What is BMR?
BMR stands for basal metabolic rate. It estimates how many calories your body burns at rest to support basic life functions.
What is the difference between BMR and TDEE?
BMR estimates resting calories. TDEE estimates total daily calories after activity is included.
Which BMR formula should I use?
Mifflin-St Jeor is a strong default for most people. Katch-McArdle can be useful when you have a reasonable body fat percentage estimate.
Is this calculator medical advice?
No. This calculator gives educational estimates. For personal nutrition, medical conditions, pregnancy, eating disorder history, or athletic performance needs, talk with a qualified healthcare professional.
Why are my calories only an estimate?
Real calorie needs can vary based on genetics, body composition, training, sleep, hormones, medications, and tracking accuracy.
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