Free Calculator Guide
BMR Calculator: Find Your Exact Daily Calorie Needs
Your Basal Metabolic Rate (BMR) is the foundation of every calorie and macro target you'll ever set — for weight loss, maintenance, or muscle gain. Here's how to calculate it accurately, and why most online calculators get it slightly wrong.
What is BMR?
BMR is the number of calories your body burns at complete rest — just to keep your heart beating, lungs breathing, and cells repairing. It does not include any movement, digestion, or exercise. For most adults, BMR accounts for 60–75% of total daily calorie burn, which is why getting it right matters more than any workout tracker.
BMR vs. TDEE
BMR is only half the picture. Your Total Daily Energy Expenditure (TDEE) multiplies BMR by an activity factor to capture how much you actually burn in a day, including exercise and daily movement (NEAT):
| Activity Level | Multiplier | Description |
|---|---|---|
| Sedentary (Little/No Exercise) | ×1.2 | Desk job, standard daily walking |
| Lightly Active (1-3 days/wk) | ×1.375 | Light exercise, recreational sports |
| Moderately Active (3-5 days/wk) | ×1.55 | Moderate workouts or active routine |
| Very Active (6-7 days/wk hard) | ×1.725 | Heavy physical training, athletic routine |
| Extra Active (Physical Job / 2x training) | ×1.9 | Hard daily physical labour & intense workouts |
Your target calorie intake for weight loss, maintenance, or muscle gain is then calculated as a percentage of TDEE — typically a 10–20% deficit for fat loss or a 10% surplus for lean muscle gain.
The two clinical BMR formulas
VITAOS calculates BMR using the same two formulas used in clinical and dietetic practice, so you can compare them side by side:
Mifflin-St Jeor (1990)
Generally considered the more accurate formula for modern populations:
- Men:
BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age + 5 - Women:
BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age − 161
Revised Harris-Benedict (1984)
An older but still widely used clinical standard:
- Men:
BMR = 66 + 13.7 × weight(kg) + 5.0 × height(cm) − 6.8 × age - Women:
BMR = 655 + 9.6 × weight(kg) + 1.8 × height(cm) − 4.7 × age
Why most BMR calculators fall short
A raw BMR/TDEE number in isolation isn't that useful on its own — what actually determines whether you hit your goal is the macro breakdown (protein, carbs, fat) built on top of it, and whether that target adjusts for real-world factors most calculators ignore, like being on a GLP-1 medication (Zepbound, Wegovy, Ozempic) that suppresses appetite and requires a higher protein floor to protect lean muscle. See our GLP-1 nutrition guide for how that adjustment works.
Calculate My BMR & TDEE Free →What you get with the free calculator
- Both Harris-Benedict and Mifflin-St Jeor formulas, side by side
- TDEE across five activity levels
- Automatic protein/carb/fat macro split for your goal
- BMI and hydration targets calculated alongside it
- No account or signup required to calculate
This calculator provides general estimates based on standard population formulas and is not a substitute for individualized medical or dietetic advice. Consult a physician or registered dietitian before making significant changes to your diet, especially if you have a medical condition or take prescription medication.