Home▸Rehabilitation & Sports Medicine▸Calorie Expenditure Calculator — BMR, TDEE & Goal Calories

🔥 Calorie Expenditure Calculator — BMR, TDEE & Goal Calories

Calculate Basal Metabolic Rate with the Mifflin-St Jeor equation, scale it to Total Daily Energy Expenditure by activity level, and see the daily calorie target for losing, maintaining or gaining weight.

Rehabilitation & Sports Medicine3DEasy60 FPS

Basal Metabolic Rate

This simulation uses the Mifflin-St Jeor equation, generally considered more accurate than the older Harris-Benedict formula: for men, BMR = 10×weight(kg) + 6.25×height(cm) − 5×age + 5; for women, BMR = 10×weight(kg) + 6.25×height(cm) − 5×age − 161. BMR is the energy your body burns at complete rest just to keep breathing, circulation and cell repair running.

From BMR to TDEE

Total Daily Energy Expenditure scales BMR by an activity factor: 1.2 for a sedentary desk job, 1.375 for light activity, 1.55 for moderate exercise, 1.725 for very active, and 1.9 for extra-active manual labour or professional training. TDEE is the calorie level at which your weight stays stable.

Setting a Calorie Goal

A daily deficit or surplus of roughly 500 kcal corresponds to about 0.45 kg (1 lb) of body-mass change per week, since roughly 7,700 kcal are stored per kilogram of body mass. This simulation applies exactly that ±500 kcal adjustment to TDEE for the Lose and Gain goals, and reports the resulting estimated weekly weight change.

About this simulation

This simulation walks through the standard three-stage energy-expenditure model used by dietitians and fitness apps: Basal Metabolic Rate (calories burned at complete rest), scaled up to Total Daily Energy Expenditure by an activity multiplier, then adjusted by ±500 kcal to hit a chosen weight-loss, maintenance or weight-gain goal.

🔬 What it shows

Three side-by-side bars — BMR, TDEE and your daily goal calories — so you can see at a glance how much of your energy budget is basal metabolism, how much extra activity adds on top, and how far your goal sits above or below maintenance.

🎮 How to use

Enter your weight, height, age and sex to compute BMR via the Mifflin-St Jeor equation, pick your activity level from Sedentary through Extra Active to scale it into TDEE, then choose Lose, Maintain or Gain to see the resulting daily calorie target and estimated weekly weight change.

💡 Did you know?

Moving from Sedentary to Very Active can raise TDEE by more than 40% for the same body — the activity multiplier alone often has a bigger effect on your calorie budget than any single dietary change, which is why non-exercise activity (walking, standing, fidgeting) matters so much for weight management.

Frequently asked questions

What is the difference between BMR and TDEE?

BMR (Basal Metabolic Rate) is the energy your body burns at complete rest — breathing, circulation, cell repair. TDEE (Total Daily Energy Expenditure) multiplies BMR by an activity factor to account for everything else you do in a day, from walking around the house to structured exercise. TDEE is always higher than BMR.

Why does this simulation use the Mifflin-St Jeor equation?

Mifflin-St Jeor (men: 10×weight + 6.25×height − 5×age + 5; women: 10×weight + 6.25×height − 5×age − 161) is generally regarded as more accurate for modern populations than the older Harris-Benedict equation from 1919, and is the formula most commonly recommended by dietitians today.

Why 500 kcal for the Lose/Gain goals?

Roughly 7,700 kcal are stored per kilogram of body mass, so a sustained daily deficit or surplus of 500 kcal works out to about 500×7/7700 ≈ 0.45 kg (1 lb) of change per week — a widely used, moderate, sustainable rate of weight change.

Why do activity levels make such a big difference?

The activity multiplier is applied to your entire BMR, not added as a flat number, so it compounds: someone with a BMR of 1,600 kcal goes from a TDEE of 1,920 kcal at Sedentary (×1.2) to 3,040 kcal at Extra Active (×1.9) — nearly double, purely from the activity factor.

Is this calculator accurate for everyone?

It is a widely used population-level estimate, not an individual measurement. Actual expenditure varies with genetics, muscle mass, hormones and health conditions; the only way to measure it precisely is indirect calorimetry. Treat the numbers here as a sensible starting point to adjust based on real-world results.

⚙ Under the hood

Three.jsBMRTDEEcalorie expenditureMifflin-St Jeor

3D · Three.js / WebGL renderer · 60 FPS target · runs fully client-side, no install