CheckBodyScore
Katch-McArdle BMR Calculator
Katch-McArdle Metabolic Rate
Comparison to Mifflin-St Jeor
Katch-McArdle is generally more accurate than Mifflin-St Jeor for very lean or very muscular individuals.
The Katch-McArdle Formula: BMR for Athletes
The **Katch-McArdle BMR Calculator** is the preferred method for calculating **Basal Metabolic Rate** (**BMR**) in individuals who have accurately measured their **Body Fat Percentage** and, consequently, their **Lean Body Mass** (**LBM**). Unlike the Mifflin-St Jeor equation, the **Katch-McArdle formula** does not use age or gender, focusing solely on the metabolically active tissue (**LBM**), which is more stable than total body weight.
The Katch-McArdle Formula
The formula is based on the constant energy requirement of lean tissue. Because muscle burns more calories than fat, accounting for **LBM** provides a superior estimate of the **resting energy expenditure** (**REE**) for **athletes** and dedicated fitness enthusiasts:
First, **LBM** is calculated: $\text{LBM} = \text{Weight} \times (1 - \text{BFP})$. The result is your daily caloric minimum, which is crucial for setting precise **calorie goals** for bulking, cutting, or maintenance.
Why LBM-Based BMR is Superior for Body Composition
If you are muscular, the Mifflin-St Jeor formula may **underestimate** your true **BMR** because it uses total weight without distinguishing muscle from fat. The **Katch-McArdle formula** solves this by relying on **Lean Body Mass** (everything but fat), making it ideal for anyone tracking **body composition** changes. We strongly recommend using our **Body Fat Percentage** calculator first, if you do not already have your **BFP** measurement.
Katch-McArdle BMR FAQs
The **Katch-McArdle BMR Calculator** is best used by **athletes** and individuals with a **low body fat percentage** who have an accurate measurement of their **BFP**. Since it uses **Lean Body Mass** (**LBM**) and ignores age/gender, it provides a more precise **BMR** than generic formulas for those with above-average muscle mass.
No. The **Katch-McArdle formula** is unique because it assumes the metabolic rate of **LBM** is the same across all adults. Therefore, it requires only **weight** and **Body Fat Percentage** (BFP) to determine **Lean Body Mass**, making the calculation gender- and age-independent.
For the most accurate **Katch-McArdle BMR** result, you need a reliable **Body Fat Percentage** (**BFP**). You can obtain this using field tests like the 3-site **Skinfold** caliper method, or lab tests like a DEXA scan. An accurate **BFP** is essential because errors in **LBM** calculation translate directly to errors in **BMR** estimation.