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Katch-McArdle TDEE Calculator

The Katch-McArdle formula stands apart from other BMR equations because it uses your **lean body mass** — not just total weight — to estimate resting metabolic rate. This makes it particularly valuable for athletes, bodybuilders, and anyone who carries significantly more (or less) muscle than the average person. Standard formulas like Mifflin-St Jeor assume an average body composition, which can overestimate BMR for people with high body fat or underestimate it for muscular individuals. If you know your body fat percentage (from a DEXA scan, Navy method calculator, or caliper test), the Katch-McArdle formula will give you a tighter, more personalised TDEE estimate.

Your Details

ℹī¸ Moderately Active Typically: Moderate exercise 3-5 days/week.

Example Use Cases

A 90 kg male bodybuilder at 12% body fat has a lean body mass of 79.2 kg. Katch-McArdle estimates his BMR at ~1,981 kcal — about 150 kcal higher than Mifflin-St Jeor would suggest, reflecting his above-average muscle mass.

A 70 kg female at 30% body fat has a lean mass of 49 kg. Katch-McArdle estimates BMR at ~1,356 kcal, slightly lower than Mifflin-St Jeor, reflecting a lower-than-average lean mass for her weight.

How to Interpret Your Results

Katch-McArdle is most useful when your body fat percentage is known with reasonable accuracy. If you're estimating body fat via visual references (which can be off by Âą5%), the advantage over Mifflin-St Jeor diminishes. For the best result, measure body fat with the Navy method or calipers first using our Body Fat Calculator.

Frequently Asked Questions

Methodology & Limitations

Formulas Used

This calculator uses three peer-reviewed BMR equations: **Mifflin-St Jeor** (1990), **Harris-Benedict (revised)** (1984), and **Katch-McArdle** (1996). Each BMR is multiplied by a standard physical activity level (PAL) factor to estimate TDEE.

Page-Specific Notes

When the user enters a body fat percentage, the calculator highlights the Katch-McArdle result as 'Recommended for your profile'. The other two formulas (Mifflin-St Jeor and Harris-Benedict) are still displayed for comparison.

Limitations

TDEE estimates can vary ±10–15% from actual expenditure. Factors like genetics, NEAT (non-exercise activity thermogenesis), hormonal status, and medication use are not captured. Use the result as a starting point and adjust based on real-world results over 2–4 weeks.

Sources & Citations

  1. Mifflin MD, St Jeor ST, et al. A new predictive equation for resting energy expenditure in healthy individuals. Am J Clin Nutr. 1990;51(2):241-247.
  2. Roza AM, Shizgal HM. The Harris Benedict equation reevaluated. Am J Clin Nutr. 1984;40(1):168-182.
  3. McArdle WD, Katch FI, Katch VL. Exercise Physiology: Energy, Nutrition, and Human Performance. 5th ed. 2001.
Last updated: 2026-02-12Reviewed by: PhysiqueLogic Editorial Team

Medical Disclaimer: This calculator provides estimates based on published formulas and is not a substitute for professional medical advice. Always consult a qualified healthcare provider before making changes to your diet or exercise routine.

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