About

Estimating daily energy needs acts as the foundational step for any nutritional strategy. This tool calculates the Total Daily Energy Expenditure or TDEE which represents the number of kilocalories required to maintain current body weight. The calculation relies on the Revised Harris-Benedict equation. This formula remains a widely used standard in clinical settings for approximating Basal Metabolic Rate or BMR. BMR accounts for the energy consumed by vital organs like the heart and lungs at complete rest.

Accuracy in these estimates prevents the common pitfalls of drastic under-eating or unintentional over-consumption. The output provides a baseline. Athletes often require higher intakes due to muscle tissue density while sedentary individuals may need less. The distinction between a Calorie and a kilocalorie often confuses users. In nutritional science contexts these terms are used interchangeably where 1 Calorie with a capital C equals 1000 small calories or 1 kcal. This tool uses kcal for technical precision.

Formulas

The calculator utilizes the Revised Harris-Benedict Equation to determine the Basal Metabolic Rate BMR. This value is then multiplied by an Activity Factor A to find the Total Daily Energy Expenditure TDEE.

Men:

BMR = 88.362 + (13.397 × W) + (4.799 × H) − (5.677 × Age)

Women:

BMR = 447.593 + (9.247 × W) + (3.098 × H) − (4.330 × Age)

Where:

W is weight in kg
H is height in cm
Age is in years

TDEE = BMR × A

Reference Data

Activity Level	Multiplier	Description	Typical Lifestyle
Sedentary	1.2	Little or no exercise	Desk job, reading, watching TV
Lightly Active	1.375	Light exercise 1-3 days/week	Teacher, light walking, house cleaning
Moderately Active	1.55	Moderate exercise 3-5 days/week	Construction work, jogging, gym classes
Very Active	1.725	Hard exercise 6-7 days/week	Agricultural work, professional athlete
Extra Active	1.9	Very hard exercise or physical job	Coal mining, marathon training, military
Sleep BMR	1.0	Basal Metabolic Rate Only	Coma, complete bed rest
Digestion (TEF)	+10%	Thermic Effect of Food	Energy used to process intake
NEAT	Variable	Non-Exercise Activity Thermogenesis	Fidgeting, standing, pacing

Frequently Asked Questions

Wearable devices estimate caloric burn using heart rate data and accelerometers which provides a real-time snapshot. This calculator uses a predictive equation based on population averages. Devices measure actual movement while this tool estimates requirements based on your input profile. Neither is 100% perfect but the calculator offers a stable baseline for planning.

If you selected an activity level like "Moderately Active" the equation already accounts for your exercise energy. Adding exercise calories on top of this TDEE result often leads to overeating (double counting). Only add extra calories if your activity level significantly exceeds the category you selected for that specific day.

The tool includes strict validation protocols. Entering a weight below 20kg or above 300kg triggers a warning. These equations are not validated for extreme underweight or extreme obesity scenarios where body composition alters metabolic predictability. In such cases clinical calorimetry is the gold standard.

Yes. In scientific terms a "calorie" (lowercase c) is the energy needed to heat 1 gram of water by 1 degree Celsius. This is too small for dietary use. Food labels use "Calories" (capital C) or "kilocalories" (kcal). 1 Calorie = 1000 calories = 1 kcal. This tool uses kcal to avoid ambiguity.

The Harris-Benedict equation does not directly factor in body fat percentage. Muscle tissue burns more energy at rest than fat tissue. If you are very muscular the result here may slightly underestimate your needs. If you have higher body fat it might slightly overestimate. The Katch-McArdle formula is an alternative if you know your exact body fat percentage.