Total Daily Energy Expenditure (TDEE) is the total number of calories your body burns in a day, combining Basal Metabolic Rate (BMR) with activity level. The Mifflin-St Jeor equation — recommended by the Academy of Nutrition and Dietetics since 2005 — estimates BMR as (10 x weight in kg) + (6.25 x height in cm) - (5 x age) - 161 for women (+5 for men). TDEE is calculated by multiplying BMR by an activity factor ranging from 1.2 (sedentary) to 1.9 (extremely active).
What is TDEE and Why Does It Matter?
TDEE (Total Daily Energy Expenditure) is the total number of calories your body burns in a day, including your basal metabolism, physical activity, and the thermic effect of food. It's the single most important number for any nutrition goal: if you eat less than your TDEE, you lose weight; if you eat more, you gain weight; if you match it, you maintain.
TDEE is calculated by multiplying your BMR (Basal Metabolic Rate) — the calories your body burns at complete rest — by an activity multiplier. The Mifflin-St Jeor equation, published in 1990 and validated across multiple populations, is more accurate than the older Harris-Benedict equation (1919) because it was developed with modern subjects and accounts for changes in average body composition over the past century.
Cutting, Maintaining, or Bulking: Which Goal is Right for You?
Your goal determines how many calories you should eat relative to your TDEE:
- Cutting (−500 cal/day) — Creates a moderate deficit to lose approximately 0.5 kg (1 lb) per week. This is the recommended rate for sustainable fat loss while preserving muscle. Protein is kept high (40%) to prevent muscle breakdown during the deficit.
- Maintaining (TDEE) — Eating at your TDEE keeps your weight stable. This is ideal for body recomposition (losing fat while gaining muscle) or simply fueling your current activity level. A balanced 30/40/30 macro split covers all bases.
- Bulking (+300 cal/day) — A moderate surplus to support muscle growth with minimal fat gain. Carbs are increased to 45% to fuel training performance and recovery. A surplus of 300 calories (rather than 500+) minimizes unnecessary fat gain — this is sometimes called a "lean bulk."
How to Calculate Your Macros
Macronutrients (macros) are the three categories of nutrients that provide calories: protein (4 cal/g), carbohydrates (4 cal/g), and fat (9 cal/g). The ratio between them affects body composition, energy levels, and performance.
This calculator assigns macro ratios based on your goal. For cutting, protein is set to 40% to maximize muscle retention during a deficit — research shows higher protein intake (up to 2.4g/kg) is critical when in a caloric deficit. For bulking, carbs are increased to 45% because carbohydrates are the primary fuel for resistance training and support recovery through glycogen replenishment.
How do popular diet macro splits compare?
Different diets distribute macronutrients in distinct ways. The table below compares the seven presets available in this calculator:
| Diet | Protein | Carbs | Fat |
|---|---|---|---|
| Balanced | 30% | 40% | 30% |
| High Protein | 40% | 30% | 30% |
| Low Carb | 35% | 25% | 40% |
| Keto | 20% | 5% | 75% |
| High Carb | 20% | 55% | 25% |
| Mediterranean | 20% | 50% | 30% |
| Zone (40/30/30) | 30% | 40% | 30% |
No single split is universally "best" — the right choice depends on your goal, food preferences, and adherence. Research consistently shows that total calorie intake and protein adequacy matter more than the exact carb/fat ratio for body composition. Pick a style you can sustain long-term, and use the Custom option if none of the presets fit your needs.
What is Body Recomposition?
Body recomposition means losing fat and gaining muscle at the same time — without traditional cutting/bulking cycles. It works best for beginners (untrained muscles respond dramatically to stimulus), people with higher body fat (more stored energy available), and those returning after a break (muscle memory allows rapid regain). The protocol: eat at maintenance, hit 2g protein per kg bodyweight, train with progressive overload, and sleep 7-9 hours.
For intermediate and advanced lifters with low body fat, traditional cut/bulk cycles are typically more efficient because the body has less "room" to simultaneously build and burn.