BMR Calculator
Overview
This free BMR calculator helps you estimate your basal metabolic rate — the number of calories your body burns at rest each day. Using evidence-based formulas including Mifflin–St Jeor, Harris-Benedict, and Katch-McArdle, this tool provides accurate calorie estimates based on your age, sex, height, weight, and activity level. You can also view your TDEE (Total Daily Energy Expenditure) to understand how many calories you burn including daily movement. Whether you're planning a diet, adjusting macros, losing weight, or building muscle, this BMR calculator gives you science-based numbers to guide your nutrition planning. All calculations run instantly in your browser — private, fast, and easy to use.
About
About BMR & Daily Energy Needs
Your BMR represents how many calories your body needs just to maintain basic functions like breathing, circulation, and cell repair. The most accurate formula for most people is the Mifflin–St Jeor equation, which is why it's the default in this calculator. If you know your body fat percentage, the Katch–McArdle formula estimates BMR using lean body mass, making it even more precise for athletes. To determine real-world calorie needs, BMR is multiplied by an activity factor to produce TDEE, your true daily calorie burn.
Features:
- Mifflin-St Jeor formula – most accurate for general population
- Harris-Benedict equation – alternative validated method
- Katch-McArdle formula – precise for athletes with known body fat %
- Activity level multipliers – sedentary to very active
- TDEE calculation – total daily energy expenditure
- Weight goal targets – loss, maintenance, and gain options
- Metric and imperial units – cm/kg or in/lb support
- Formula comparison – view results from multiple methods
- 100% client-side – no data storage or transmission
- No registration required – instant results
FAQ
What is a normal BMR?
Most adults have a BMR between 1,200–2,000 calories depending on size, age, and sex. Larger individuals and men typically have higher BMRs.
Which BMR formula is most accurate?
Mifflin–St Jeor is the most reliable for general use. Katch-McArdle is best if you know your body fat %, as it accounts for lean body mass.
Is BMR the same as TDEE?
No. BMR is resting calories; TDEE includes movement and daily activity. TDEE = BMR × activity multiplier.
Does muscle increase BMR?
Yes. Lean mass increases metabolic rate significantly. Athletes and muscular individuals have higher BMRs than sedentary people of the same weight.
How do I use this for weight loss?
Use the standard loss target (TDEE - 500 kcal) for approximately 1 lb/week loss. Mild loss (-250 kcal) is slower but more sustainable.
Can I use this for bulking?
Yes. Use the mild gain (+250 kcal) or standard gain (+500 kcal) targets. Combine with strength training for best results.
Why do my results differ from other calculators?
Different formulas produce different results. Mifflin-St Jeor is generally most accurate, but individual variation is normal.
Is this medical advice?
No. These are estimates for general fitness and nutrition planning. Consult a healthcare professional or registered dietitian for personalized advice.