About TDEE Steps

TDEE Steps is a set of free energy-expenditure calculators that show their working. Instead of a single number, every calculator writes out the equation, substitutes your values and shows each intermediate result, so you can check the math yourself.

Who makes TDEE Steps

TDEE Steps is built and maintained by Houji, an independent developer. I am not a doctor, dietitian or registered nutrition professional, and no medical professional has reviewed this site. What I can stand behind is the arithmetic: every equation is listed below with where it comes from, and every step is shown so you can check it.

How the numbers are checked

Each equation is implemented exactly as written in its source and checked against hand-worked reference cases, which are kept as automated tests in the site’s code. For example, a 30-year-old man weighing 70 kg at 175 cm gives a Mifflin-St Jeor BMR of 1648.75 kcal/day and, moderately active, a TDEE of about 2556 kcal/day. Unit conversions are tested so that switching between metric and imperial never changes a result.

Last reviewed: October 20, 2026.

The equations

Mifflin-St Jeor (the main calculator): Mifflin MD, St Jeor ST, Hill LA, Scott BJ, Daugherty SA, Koh YO. “A new predictive equation for resting energy expenditure in healthy individuals.” American Journal of Clinical Nutrition, 1990;51(2):241-247.

Katch-McArdle (the body fat calculator): BMR = 370 + 21.6 × lean body mass in kg, as presented in McArdle WD, Katch FI, Katch VL, Exercise Physiology: Nutrition, Energy, and Human Performance (Lippincott Williams & Wilkins). It follows the lean-mass approach of Cunningham JJ, “A reanalysis of the factors influencing basal metabolic rate in normal adults,” American Journal of Clinical Nutrition, 1980;33(11):2372-2374.

Adaptive estimate (the adaptive calculator): works backwards from your own intake and weight change, treating one kilogram of body mass change as roughly 7,700 kcal. That figure is a widely used approximation, not an exact constant.

Steps-based estimate (the steps calculator): Mifflin-St Jeor BMR × 1.2, plus your daily steps × body weight × the net energy cost of one step. That cost uses the simple cadence-based metabolic equation for walking from Moore CC, Aguiar EJ, Ducharme SW, Tudor-Locke C, “Development of a Cadence-based Metabolic Equation for Walking,” Medicine & Science in Sports & Exercise, 2021;53(1):165-173, minus resting oxygen uptake (3.5 mL/kg/min), at about 5 kcal per litre of oxygen.

The activity multipliers (1.2, 1.375, 1.55, 1.725 and 1.9) are the most commonly published set used alongside these equations.

What these numbers are

These equations were developed in healthy adults, so all three calculators are intended for ages 18 and over and are not meant for pregnancy or breastfeeding. The Mifflin-St Jeor calculator asks for age and gives no result under 18; the body fat and adaptive calculators do not ask for age, so the same limit is stated next to them instead. Every result is an estimate. Individual metabolism varies, and predictive equations carry real error for any one person. Treat the number as a starting point and adjust it from your own weight trend over a few weeks. Intermediate steps are shown exactly where possible; values marked ≈ were rounded for display, and only the final result is rounded to a whole number.

This site is for general information only and is not medical or nutritional advice. If you are pregnant, managing a medical condition, or have a history of disordered eating, talk to a qualified professional before changing what you eat.