# FreeTDEECalculator.app

> FreeTDEECalculator.app is a free, evidence-based human metabolism calculation suite and educational knowledge base. It provides clinical-grade predictive equations for Total Daily Energy Expenditure (TDEE), Basal Metabolic Rate (BMR), caloric deficits, macronutrient distribution, and step-based non-exercise activity thermogenesis.

## Core Calculators

- [TDEE Calculator](https://freetdeecalculator.app/): Calculates daily maintenance calories using the Mifflin-St Jeor, Revised Harris-Benedict, and Katch-McArdle equations with real-time activity adjustments.
- [Calorie Deficit Calculator](https://freetdeecalculator.app/calorie-deficit-calculator/): Calculates safe caloric deficit sizing, projected fat loss timelines (0.5 to 2.0 lbs/week), and metabolic minimum safety thresholds.
- [Macro Calculator](https://freetdeecalculator.app/macro-calculator/): Translates daily caloric targets into precise gram allocations for protein, carbohydrates, and dietary fats across Balanced, High Protein, Low Carb, and Ketogenic distributions.
- [BMR Calculator](https://freetdeecalculator.app/bmr-calculator/): Computes baseline energy requirements required to sustain vegetative biological life at complete rest in a thermo-neutral state.
- [Intermittent Fasting Calculator](https://freetdeecalculator.app/intermittent-fasting-calculator/): Aligns 16:8, 18:6, and 20:4 time-restricted feeding protocols with daily energy expenditure and eating window targets.
- [Steps-Based TDEE Calculator](https://freetdeecalculator.app/tdee-calculator-with-steps/): Converts wearable step counts directly into Non-Exercise Activity Thermogenesis (NEAT) and calibrated daily energy burn.

## Guides & Educational Resources

- [What is TDEE?](https://freetdeecalculator.app/learn/what-is-tdee/): Comprehensive guide covering the 4 biological components: Basal Metabolic Rate (BMR), Non-Exercise Activity Thermogenesis (NEAT), Thermic Effect of Food (TEF), and Exercise Activity Thermogenesis (EAT).
- [TDEE vs BMR](https://freetdeecalculator.app/learn/tdee-vs-bmr/): Clarifies the critical difference between resting metabolic rate and total daily expenditure, explaining why BMR serves as a physiological intake floor.
- [Activity Level Guide](https://freetdeecalculator.app/learn/activity-level-guide/): Practical decision matrix and step-count benchmarks resolving the "desk job with 3-4 workouts per week" activity multiplier dilemma.
- [Beginner's Guide to TDEE & CICO](https://freetdeecalculator.app/blog/tdee-calculator-beginners-guide/): Step-by-step introduction to Calories In, Calories Out (CICO), food scale measurement, and setting sustainable fat loss deficits.
- [TDEE Calculator Accuracy](https://freetdeecalculator.app/blog/how-accurate-is-tdee-calculator/): Analysis of formula error margins (plus or minus 10% to 15%), user activity overestimation, wearable tracker inaccuracies, and a 2-week calibration protocol.
- [TDEE vs BMR for Weight Loss](https://freetdeecalculator.app/blog/tdee-vs-bmr-weight-loss/): The "Sandwich Method" for weight loss dieters: eating below TDEE while staying above BMR to prevent metabolic downregulation.

## Scientific Formulas & Multipliers

### 1. Basal Metabolic Rate (BMR)

#### Mifflin-St Jeor Equation (Clinical Standard)
- **Men:** BMR = (10 × weight_kg) + (6.25 × height_cm) - (5 × age_years) + 5
- **Women:** BMR = (10 × weight_kg) + (6.25 × height_cm) - (5 × age_years) - 161

#### Katch-McArdle Equation (Lean Body Mass)
- BMR = 370 + (21.6 × LBM_kg)
- LBM_kg = weight_kg × (1 - (body_fat_percentage / 100))

### 2. Physical Activity Level (PAL) Multipliers
- **Sedentary (desk job, < 5,000 steps/day):** TDEE = BMR × 1.200
- **Lightly Active (1-3 exercise days/week, 5,000-7,999 steps/day):** TDEE = BMR × 1.375
- **Moderately Active (3-5 exercise days/week, 8,000-11,999 steps/day):** TDEE = BMR × 1.550
- **Very Active (6-7 heavy training days/week, 12,000-15,000 steps/day):** TDEE = BMR × 1.725
- **Extremely Active (athletes, heavy manual labor, 15,000+ steps/day):** TDEE = BMR × 1.900

### 3. Macronutrient Energy Equivalents
- **Protein:** 4 kcal per gram (TEF: 20% to 30%)
- **Carbohydrates:** 4 kcal per gram (TEF: 5% to 10%)
- **Dietary Fat:** 9 kcal per gram (TEF: 0% to 3%)