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Health & BiophysicsEntry № 02.03Verified ISO Standard

Daily Calorie & TDEE Calculator (Mifflin-St Jeor)

A clinical metabolic rate model calculating Basal Metabolic Rate (BMR) and Total Daily Energy Expenditure (TDEE).

Popular Searches:How many calories should I eat per day to lose weight?BMR vs TDEE: What is the difference?Calorie deficit calculation (500 kcal rule for 0.5kg/week)Mifflin-St Jeor formula for men and women
Mifflin-St Jeor Caloric & TDEE Engine
Daily Caloric Target
Maintenance Intake (TDEE)
2,350
Basal Metabolic Rate: 1709 kcal
Weight Loss Target500 kcal deficit (~0.5 kg/week)
1850 kcal
Weight Gain Target500 kcal surplus for hypertrophy
2850 kcal
Mifflin-St Jeor: BMR = 10w + 6.25h − 5a + s
Mathematical Proof & FormulaISO-80000-2 Notation

How This Calculation Formula is Formulated

The Mifflin-St Jeor equation is clinically recognized by the American Dietetic Association as the gold standard predictive model for resting energy expenditure. BMR measures the energy required to sustain vital organ function at complete rest. TDEE is calculated by scaling BMR by a physical activity level factor (PAL) ranging from 1.2 (sedentary) to 1.9 (extremely active).

Standard Algebraic Representation
BMR = 10·w(kg) + 6.25·h(cm) − 5·a(y) + s (Men: s=+5, Women: s=−161)
Verified against regulatory standards and peer-reviewed conventions.

Variable Definitions & Measurement Units

w
Body Weight (kg)
Total gravitational mass measured in kilograms.
h
Height (cm)
Standing stature height measured in centimeters.
a
Chronological Age
Age in years (metabolic rate slows by approximately 5 kcal/year).
s
Sex Constant
Biological sex constant reflecting endocrine differences (+5 for men, −161 for women).
Step-by-Step Calculation Example

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):

1
Weight Contribution (10 × w)
10 × 80 kg = 800 kcal
Basal mass maintenance component.
2
Height Contribution (6.25 × h)
6.25 × 180 cm = 1,125 kcal
Body surface area thermal component.
3
Age Deduction (5 × a)
5 × 30 years = 150 kcal
Age-related metabolic decline.
4
Combine for Basal Metabolic Rate (BMR)
800 + 1,125 − 150 + 5 (male) = 1,780 kcal/day
Energy burned at complete bedrest.
5
Scale by Activity (TDEE = BMR × 1.55)
1,780 × 1.55 = 2,759 kcal/day
Daily maintenance intake to keep weight constant.
6
Weight Loss Deficit (500 kcal reduction)
2,759 − 500 = 2,259 kcal/day
Predicts ~0.5 kg (1 lb) of fat loss per week.
Conclusion: The individual requires 2,759 kcal daily to maintain current weight. Consuming 2,259 kcal per day creates a steady 500 kcal deficit, yielding safe, sustainable fat loss.
In-Depth Editorial Analysis

Energy Balance Thermodynamics & The 3,500 kcal Rule

Body composition change adheres strictly to the First Law of Thermodynamics: Energy In minus Energy Out equals Δ Storage. One pound of adipose tissue stores approximately 3,500 kilocalories of metabolic chemical energy.

Creating a cumulative deficit of 500 calories per day over 7 days produces a 3,500 calorie shortfall, translating directly into approximately 1 pound (0.45 kg) of fat loss per week.

Frequently Asked Questions

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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Deterministic Precision & 100% Client-Side Privacy

All calculations execute in your local browser using IEEE 754 double-precision floating-point arithmetic. Your figures and financial metrics remain private and are never uploaded or saved to any cloud servers.