BMR Calculator

Our BMR Calculator helps you determine your baseline caloric needs with medical-grade precision. Here's how to use it:

Step 1: Select your biological sex. Men and women have different average muscle-to-fat ratios, which significantly impacts metabolic rate.

Step 2: Enter your age. Basal metabolic rate naturally slows as we age due to changes in hormonal balance and muscle mass.

Step 3: Enter your current height and weight. These dimensions determine your body surface area and the energy required to maintain basic organ function.

Step 4: (Optional) Enter your body fat percentage. If you have this data from a DEXA scan or calipers, our tool will switch to the Katch-McArdle formula, which is much more accurate for athletes and individuals with non-average body compositions.

Step 5: Click 'Calculate'. You will receive your BMR (calories burned doing nothing) and your TDEE (Total Daily Energy Expenditure), which accounts for your daily movement and exercise. Use the TDEE as your 'maintenance' calorie target.

We use two primary formulas:

1. Mifflin-St Jeor: Used when body fat is unknown. Generally the most accurate for modern populations. - Men: (10 × weight) + (6.25 × height) - (5 × age) + 5 - Women: (10 × weight) + (6.25 × height) - (5 × age) - 161

2. Katch-McArdle: Used if body fat percentage is provided. It focuses on Lean Body Mass (LBM). - BMR = 370 + (21.6 × LBM in kg)

TDEE is determined by multiplying BMR by an activity factor (1.2 for sedentary to 1.9 for extra active).

Basal Metabolic Rate (BMR) is the amount of energy (calories) your body needs to keep its most basic functions working while at rest. These functions include breathing, circulating blood, controlling body temperature, cell growth, brain and nerve function, and contraction of muscles. Even when you are sleeping, your body is hard at work burning energy to keep you alive.

This calculator utilizes the Mifflin-St Jeor equation, which is currently considered the most accurate formula for the general population in clinical settings. By understanding your BMR, you can make more informed decisions about your nutrition and fitness goals. To lose weight, you must consume fewer calories than your TDEE; to gain weight, you must consume more. However, it is generally recommended never to eat fewer calories than your BMR, as this can lead to metabolic slowdown, nutrient deficiencies, and muscle loss.

Important Medical Disclaimer: Caloric needs can vary significantly based on genetics, hormonal health, and medications. This calculator is for educational purposes only and should not replace advice from a registered dietitian or medical professional, especially if you have a history of eating disorders or metabolic conditions.