BMR Calculator
Calculate your Basal Metabolic Rate using the Mifflin-St Jeor equation
What This Calculator Does
Your Basal Metabolic Rate (BMR) is the number of calories your body needs to perform basic life-sustaining functions like breathing, circulation, and cell production while at complete rest. The Mifflin-St Jeor equation used here is considered the most accurate BMR formula for most people. Your BMR typically accounts for 60 to 75 percent of your total daily calorie burn.
The Formula
Example Calculations
Example: 30-year-old male
A 30-year-old man weighing 180 lbs (81.6 kg) at 72 inches (182.9 cm). BMR = 10(81.6) + 6.25(182.9) - 5(30) + 5 = 1,814 calories per day at rest.
Example: 28-year-old female
A 28-year-old woman weighing 135 lbs (61.2 kg) at 64 inches (162.6 cm). BMR = 10(61.2) + 6.25(162.6) - 5(28) - 161 = 1,307 calories per day at rest.
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How to Use Your Results
Your BMR is the foundation of your daily calorie needs. It represents the minimum calories your body requires for basic functions. Never eat below your BMR for extended periods, as this can slow your metabolism and lead to muscle loss. To find your total daily needs, multiply your BMR by your activity factor or use our TDEE calculator for a complete picture.
Frequently Asked Questions
How accurate is the BMR Calculator?
The BMR Calculator uses well-established scientific formulas to provide reliable estimates. The Mifflin-St Jeor equation has been shown to estimate BMR within 10 percent of measured values for most healthy adults. For precise measurements, consult a healthcare professional or certified personal trainer.
Is the BMR Calculator free to use?
Yes, the Fitnit BMR Calculator is completely free with no sign-up required. Enter your values and get instant results. You can use it as many times as you like.
What formula does the BMR Calculator use?
The Mifflin-St Jeor equation is used: BMR = 10 x weight(kg) + 6.25 x height(cm) - 5 x age + 5 for men (or -161 for women). This equation was published in 1990 and has been validated as one of the most accurate BMR prediction formulas.
How often should I recalculate my bmr in calories/day?
We recommend recalculating every 4 to 6 weeks, or whenever your weight, activity level, or fitness goals change significantly. Regular updates ensure your targets stay aligned with your current body and lifestyle.
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