0. Why TDEE matters — the foundation of every nutrition plan
Total Daily Energy Expenditure (TDEE) is the number of calories your body burns in a 24-hour period including basal metabolism, the thermic effect of food, non-exercise activity thermogenesis (NEAT), and intentional exercise. Every weight-loss, weight-gain, and body-recomposition plan starts here. Without an accurate TDEE estimate you are flying blind: a 300-kcal-per-day error compounds into a 9-kg-per-year swing in body mass for sedentary adults. This calculator gives you three independently validated formulas so you can sanity-check the result, then translates the calorie target into protein, fat, and carbohydrate grams using five science-backed macro presets.
1. BMR Formulas — Which to Use?
The calculator supports three formulas. Select the one that best fits your data:
| Formula | Best for | Inputs needed |
|---|---|---|
| Mifflin-St Jeor | General population — most validated (2002 ADA recommendation) | Sex, age, height, weight |
| Harris-Benedict (revised) | Historical standard; tends to run 5–10% higher | Sex, age, height, weight |
| Katch-McArdle | Athletes, very lean/obese individuals with known body-fat % | Weight + body fat % |
2. BMR — Mifflin-St Jeor (default)
Male: 10 × kg + 6.25 × cm − 5 × age + 5 Female: 10 × kg + 6.25 × cm − 5 × age − 161
Current gold standard for the general population (±10% for most). Recommended by the American Dietetic Association since 2002.
3. BMR — Harris-Benedict (Roza & Shizgal 1984 revision)
Male: 88.362 + 13.397 × kg + 4.799 × cm − 5.677 × age Female: 447.593 + 9.247 × kg + 3.098 × cm − 4.330 × age
Older formula, generally predicts 5–10% higher BMR than Mifflin. Useful for comparison or when you've seen this formula used in research references.
4. BMR — Katch-McArdle (lean mass based)
BMR = 370 + 21.6 × lean body mass (kg) lean mass = weight × (1 − body fat % / 100)
More accurate for athletic or very lean/obese individuals when body-fat % is known. Enter body fat % on the calculator to enable this option.
5. Activity multipliers (TDEE)
| Level | Multiplier |
|---|---|
| Sedentary (desk job) | × 1.2 |
| Light (1–3 days/week) | × 1.375 |
| Moderate (3–5 days) | × 1.55 |
| Active (6–7 days) | × 1.725 |
| Very active (2×/day, manual labor) | × 1.9 |
6. Goal-based target kcal
- Lose: TDEE − 500 kcal (≈ 0.45 kg/week)
- Maintain: TDEE
- Gain: TDEE + 300 kcal (≈ 0.25 kg/week)
- Cut: TDEE × 0.8, minimum 1,200 kcal
7. Macro Presets — Protein/Fat/Carb ratios
| Preset | Protein | Fat | Carbs | Best for |
|---|---|---|---|---|
| Balanced | 30% | 30% | 40% | General fitness, recomp |
| High Protein | 40% | 25% | 35% | Muscle building, cutting with muscle retention |
| Keto | 25% | 70% | 5% | Ketogenic diet, insulin sensitivity, seizure management |
| Zone | 30% | 30% | 40% | Zone diet / anti-inflammatory approach (same as Balanced) |
| Low Fat | 25% | 15% | 60% | Endurance athletes, high-volume training, cholesterol management |
Note: The default "Balanced" mode uses goal-based protein (1.6–2.2 g/kg body weight), not a fixed percentage, which is more accurate for body composition goals.
8. When to deviate
- Endurance athletes benefit from higher carbs (50–60% of kcal) — use Low Fat preset.
- Strict keto requires fat 70%+ and carbs under 50g/day — use Keto preset.
- Older adults may need protein as high as 2.0 g/kg to preserve muscle.
- If formulas disagree significantly (>200 kcal), provide body fat % for Katch-McArdle.
9. Putting it together — a worked example
Take a 32-year-old male, 178 cm, 80 kg, moderate activity (gym 3–5 days/week), goal: lose 0.5 kg/week with muscle retention.
- BMR (Mifflin): 10 × 80 + 6.25 × 178 − 5 × 32 + 5 = 800 + 1112.5 − 160 + 5 = 1757.5 kcal.
- TDEE: 1757.5 × 1.55 = 2724 kcal maintenance.
- Cut target: 2724 − 500 = 2224 kcal/day.
- Protein: 2.0 g/kg × 80 kg = 160 g = 640 kcal (29%).
- Fat: 25% of 2224 = 556 kcal = 62 g.
- Carbs: 2224 − 640 − 556 = 1028 kcal = 257 g (46%).
Two weeks later, the scale stalls. Possibilities: NEAT compensation (body unconsciously moves less), water retention from cortisol or training, measurement error, or the original TDEE estimate was 100–200 kcal high. The fix is to re-weigh on the same day of the week for 7-day rolling averages instead of single weigh-ins, and adjust the calorie target by ±100 kcal every 2–3 weeks until rate of loss matches the goal.
10. Common mistakes when interpreting TDEE numbers
- Treating the result as exact. Even the best formula has a ±10% standard deviation. Use it as a starting point and adjust based on real weight-trend data over 2–4 weeks.
- Choosing the activity multiplier optimistically. The biggest source of error: people log 5 gym sessions a week but spend the rest of the day sedentary. Office worker + 3 gym sessions is usually 1.375 (light), not 1.55 (moderate).
- Cutting too aggressively. A 1000 kcal deficit produces muscle loss, hormonal disruption, and rebound eating for most people. Cap deficits at 25% below TDEE.
- Ignoring protein during cuts. Protein intake of 1.6–2.2 g/kg prevents most of the muscle loss that would otherwise accompany a calorie deficit. This is the single most important macro for body composition.
- Forgetting fiber and micronutrients. Macros are 80% of the picture — the other 20% (fiber 25–35 g/day, vitamins from real food, hydration 30–40 ml/kg) determines whether the diet is sustainable.
11. References & further reading
- Mifflin et al., Am J Clin Nutr 1990. A new predictive equation for resting energy expenditure in healthy individuals.
- Roza & Shizgal, Am J Clin Nutr 1984 (Harris-Benedict revision).
- Katch-McArdle, Exercise Physiology. Lean-mass-based BMR derivation.
- ISSN Position Stand: Protein & Exercise (Stokes et al., 2018).
- Trexler et al., JISSN 2014. Metabolic adaptation to weight loss.
This guide is for educational purposes only and is not medical or nutritional advice. Consult a registered dietitian for personalized planning, especially if you have metabolic, kidney, or eating-disorder history.