Maintenance Calories & Macros Estimate
Estimate a daily maintenance-calorie and macro reference range from published formulas. The output is an estimated range, not a diet prescription, and it does not replace advice from a doctor or registered dietitian.
Calculation basis and sources
Every formula, coefficient and band width this page uses is listed below. The numbers follow from these rules alone — no empirical tweaks, no AI.
1. Basal metabolic rate
Main basis, Mifflin-St Jeor: male BMR = 10×weight(kg) + 6.25×height(cm) − 5×age + 5; female BMR = 10×weight(kg) + 6.25×height(cm) − 5×age − 161.
Source: Mifflin MD, St Jeor ST, et al. “A new predictive equation for resting energy expenditure in healthy individuals.” American Journal of Clinical Nutrition, 1990;51(2):241–247.
Second basis, Katch-McArdle: BMR = 370 + 21.6 × lean mass(kg), where lean mass = weight × (1 − body-fat%). Computed only when body fat is entered, as a cross-check; it does not replace the main basis.
Source: the lean-mass prediction of Katch and McArdle, in “Exercise Physiology: Nutrition, Energy, and Human Performance”. Measurement error in the body-fat figure carries straight into the result, so it is offered only as an optional second basis.
2. Activity factors (multiplied by BMR for the point estimate)
| Daily activity level | Factor | What it describes in practice |
|---|---|---|
| Sedentary | ×1.2 | Desk-based or at home, essentially no training, under 5,000 steps a day. |
| Light | ×1.375 | Training 1–3 times a week, otherwise mostly seated. |
| Moderate | ×1.55 | Training 3–5 times a week, plus everyday walking (roughly 7,000–10,000 steps a day). |
| High | ×1.725 | Training 6–7 times a week, or training plus standing/carrying work. |
| Very high | ×1.9 | Two sessions a day, or heavy physical work alongside 5+ sessions a week. |
3. Goal bands
Maintain = point estimate ±10%; gentle fat loss = −20% to −10%; gentle muscle gain = +5% to +15%. All three are ranges; the page never outputs a single “intake” number.
4. Macro ranges
Protein: 1.6–2.2 g per kg of body weight. This is a general recommended range for people who train with weights, not an individual prescription; it does not change with the calorie band.
Fat: 20%–35% of that band's calories, converted at 9 kcal/g.
Carbohydrate: the remainder after protein and fat, at 4 kcal/g; the low end uses the most conservative combination and is never below 0.
5. Units and rounding
1 jin = 0.5 kg; 1 inch = 2.54 cm, 1 foot = 12 inches. Calculations run in kg and cm, while the page keeps the units you typed.
6. Input ranges
Weight 20–300 kg, height 100–250 cm, age 18–100, body fat 3%–60%. Out of range the page only warns and shows nothing — the formulas carry no usable meaning outside these bounds.
Calories are rounded to 10 kcal and grams to 5 g: deliberately not precise to the unit.
7. Version and updates
- Formula and coefficient version (in code): energy_v1
- Page basis version: 2026-09-15
- Last updated: 2026-09-15
- Review state: confirmed by a reviewer
The formulas and coefficients were confirmed item by item by the reviewer on 2026-09-15; an estimate is still an estimate, and individual variation can reach ±20%.