Daily Calorie & TDEE Calculator
Calculate your daily calorie needs and burn rate for weight loss, maintenance, or muscle gain.
How This Calculation Formula is Formulated
The Mifflin-St Jeor equation is a widely referenced and validated predictive equation for estimating resting energy expenditure (REE/BMR). BMR measures the energy required to sustain vital physiological functions at complete rest. TDEE is estimated by scaling BMR by a physical activity level factor (PAL) ranging from 1.2 (sedentary) to 1.9 (extremely active).
Variable Definitions & Measurement Units
Worked Calorie & TDEE Example
Calculate the daily maintenance and fat-loss calories for a 30-year-old male weighing 80 kg with a height of 180 cm who exercises moderately (3-5 days/week, PAL = 1.55):
Energy Balance Thermodynamics & The 3,500 kcal Guideline
A 500 kcal/day deficit across 7 days theoretically creates a ~3,500 kcal shortfall, which roughly approximates the chemical energy in one pound (0.45 kg) of adipose tissue.
However, real-world body mass alteration is non-linear: metabolic adaptation, water and glycogen shifts, non-exercise activity thermogenesis (NEAT), and hormonal factors cause actual weight change to vary across individuals.
Frequently Asked Questions About Calorie Calculator
What is the difference between BMR and TDEE?
BMR (Basal Metabolic Rate) is the bare minimum energy your body requires to keep your heart beating, lungs breathing, and brain functioning at total rest. TDEE (Total Daily Energy Expenditure) includes all movement, work, digestion (TEF), and athletic exercise.
Can eating too few calories damage my metabolism?
Severe calorie restriction triggers adaptive thermogenesis (commonly called 'starvation mode'), where non-exercise activity thermogenesis (NEAT) drops and thyroid hormones downregulate. A moderate deficit of 300-500 kcal avoids this while preserving lean muscle mass.
How many calories should I eat to gain lean muscle mass?
For lean muscle hypertrophy, consume a modest surplus of 250-350 kcal above maintenance combined with progressive resistance training and 1.6-2.2 grams of protein per kilogram of body weight.
Why does Mifflin-St Jeor outperform the older Harris-Benedict formula?
Validated in clinical trials by the American Dietetic Association, Mifflin-St Jeor was found to be within 10% of measured calorimetry in over 82% of non-obese and obese subjects, whereas the 1919 Harris-Benedict formula systematically overestimates energy expenditure by 5% or more.
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