# BMR Calculator

> Calculate your Basal Metabolic Rate—the calories your body needs to function at rest—using the accurate Mifflin-St Jeor formula.

**Category:** Health
**Keywords:** bmr, metabolism, calories, health, fitness, math
**URL:** https://complete.tools/bmr-calc

## How it calculates

Bmr Calc uses the Mifflin-St Jeor equation to calculate BMR. The formula is as follows: 
For men: BMR = 10 × weight(kg) + 6.25 × height(cm) - 5 × age(years) + 5 
For women: BMR = 10 × weight(kg) + 6.25 × height(cm) - 5 × age(years) - 161. 
In this formula, 'weight' is the individual's body mass in kilograms, 'height' is the person's height in centimeters, and 'age' is their age in years. The constants (10, 6.25, 5, and 161 for women) are derived from population studies that indicate average metabolic rates. The relationship established by this formula allows for the estimation of calorie needs based on fundamental biological differences between sexes and variations in body composition.

## Who should use this

Personal trainers calculating caloric needs for clients during weight loss programs. Nutritionists advising clients on daily caloric intake for health maintenance. Athletes determining their energy requirements to optimize performance and recovery. Researchers conducting studies related to metabolism across different demographics.

## Worked examples

Example 1: A 30-year-old woman weighing 70 kg and 165 cm tall. 
Using the formula for women: BMR = 10 × 70 + 6.25 × 165 - 5 × 30 - 161. 
Calculating: BMR = 700 + 1031.25 - 150 - 161 = 1420.25 kcal/day. 
This woman would require approximately 1420 kcal/day at rest.

Example 2: A 45-year-old man weighing 85 kg and 180 cm tall. 
Using the formula for men: BMR = 10 × 85 + 6.25 × 180 - 5 × 45 + 5. 
Calculating: BMR = 850 + 1125 - 225 + 5 = 1755 kcal/day. 
This man’s BMR indicates he needs around 1755 kcal/day to maintain his body functions at rest.

## Limitations

Bmr Calc has specific limitations including: 1) It assumes individuals have a standard body composition; those with high muscle mass or significant body fat may see inaccuracies. 2) It does not account for factors like hormonal changes, which can affect metabolism. 3) The Mifflin-St Jeor equation may not be as accurate for very tall or very short individuals due to its reliance on average population data. 4) BMR is calculated without consideration of individual metabolic variations, which can lead to discrepancies in caloric needs.

## FAQs

**Q:** How does BMR differ from TDEE?


**A:** BMR represents the number of calories needed at rest, while TDEE accounts for all calories burned in a day, including physical activity. 


**Q:** Why is the Mifflin-St Jeor equation preferred over other BMR equations?


**A:** The Mifflin-St Jeor equation is considered more accurate than previous equations, like the Harris-Benedict, for estimating BMR across different populations. 


**Q:** Can BMR calculations vary with different activity levels?


**A:** Yes, while BMR is a static measurement, TDEE varies with activity levels, necessitating adjustments based on lifestyle. 


**Q:** What role does body composition play in BMR calculations?


**A:** Body composition affects metabolic rate; individuals with higher muscle mass generally have higher BMRs compared to those with higher fat percentages.

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*Generated from [complete.tools/bmr-calc](https://complete.tools/bmr-calc)*