BMR Calculator
What is BMR?
BMR Calculator Overview
Our BMR Calculator estimates your Basal Metabolic Rate (BMR), which is the number of calories your body needs to maintain basic functions at rest. This information can be used to help you manage your weight and optimize your diet.
What is Basal Metabolic Rate (BMR)?
Basal Metabolic Rate (BMR) is the amount of energy your body uses daily when at complete rest. It accounts for about 60-75% of your daily calorie expenditure and includes energy used for essential functions like:
- Breathing
- Circulation
- Nutrient processing
- Cell production
Factors Affecting BMR
Several factors can influence your BMR:
- Age: BMR tends to decrease with age.
- Sex: Men generally have higher BMRs than women due to more muscle mass.
- Body Composition: Muscle burns more calories than fat, so people with more muscle mass have higher BMRs.
- Genetics: Genetic factors can influence metabolic rate.
- Hormone Levels: Thyroid hormones play a significant role in regulating BMR.
How to Use BMR for Weight Management
Knowing your BMR can help you estimate your daily calorie needs for weight maintenance, loss, or gain:
- Weight Maintenance: Consume calories equal to your BMR multiplied by an activity factor.
- Weight Loss: Create a calorie deficit by consuming fewer calories than your BMR multiplied by an activity factor.
- Weight Gain: Consume more calories than your BMR multiplied by an activity factor.
BMR Calculation Formulas
Our calculator uses the following formulas to estimate BMR:
Mifflin-St Jeor Equation
Considered the most accurate for most people:
- For men: BMR = 10W + 6.25H - 5A + 5
- For women: BMR = 10W + 6.25H - 5A - 161
Revised Harris-Benedict Equation
An updated version of one of the earliest methods for estimating BMR:
- For men: BMR = 13.397W + 4.799H - 5.677A + 88.362
- For women: BMR = 9.247W + 3.098H - 4.330A + 447.593
Katch-McArdle Formula
Estimates Resting Daily Energy Expenditure (RDEE) by including lean body mass:
- BMR = 370 + 21.6(1 - F)W
Variables:
- W: Body weight (kg)
- H: Height (cm)
- A: Age (years)
- F: Body fat percentage (expressed as a decimal)
Disclaimer
BMR calculations are estimates and may not accurately reflect individual metabolic rates. Consult with a healthcare professional or registered dietitian for personalized advice.
How to Use the BMR Calculator
1Enter Your Personal Information
- Select your preferred unit system (US or Metric)
- Enter your age (between 15-80 years)
- Select your biological sex (affects the calculation formula)
- Enter your height and weight accurately
2Choose Additional Settings
- Select your preferred results unit (Calories or Kilojoules)
- Choose a BMR formula that suits your needs:
- Mifflin-St Jeor: Most accurate for general population
- Harris-Benedict: Alternative formula, sometimes preferred
- Katch-McArdle: Best when body fat percentage is known
- If using Katch-McArdle, enter your body fat percentage
3Understand Your Results
- BMR: The number of calories your body needs at complete rest
- Daily calorie needs: BMR multiplied by activity level factors
- Different activity levels show how many calories you need based on your exercise frequency
- These values represent maintenance calories (to maintain current weight)
4Apply Your Results
- Weight maintenance: Consume calories equal to your activity level
- Weight loss: Create a moderate deficit of 500-1000 calories/day
- Weight gain: Consume 300-500 calories above your activity level
- Track your food intake and adjust based on results over 2-4 weeks
Important Considerations
- BMR calculations are estimates and may vary by ±10% from your actual BMR
- Never consume fewer calories than your BMR for extended periods
- Consult with a healthcare provider before making significant dietary changes
- Recalculate your BMR after significant weight changes (±10 lbs/5 kg)
- For medical conditions affecting metabolism, work with healthcare professionals
BMR Formula Comparison
| Formula | Best For | Accuracy | Considerations |
|---|---|---|---|
| Mifflin-St Jeor | General population | ±10% | Most widely recommended by nutrition professionals |
| Harris-Benedict | Historical comparison | ±15% | Older formula, may overestimate BMR slightly |
| Katch-McArdle | Athletes, bodybuilders | ±8% | Requires accurate body fat percentage measurement |