Macro calculation
The math behind the targets — Mifflin-St Jeor, TDEE, goal and Atwater distribution.
This page describes, step by step, how MacroMath arrives at your daily calorie and macronutrient targets. The whole calculation is deterministic and can be reconfigured manually.
1. Basal Metabolic Rate (BMR)
The app estimates resting energy with the Mifflin-St Jeor predictive equation:
Male: BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age(years) + 5
Female: BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age(years) − 1612. Total Daily Energy Expenditure (TDEE)
BMR is multiplied by a physical activity coefficient (collected in the initial quiz):
| Activity level | Coefficient |
|---|---|
| Sedentary | 1.2 |
| Light | 1.375 |
| Moderate | 1.55 |
| Active | 1.725 |
| Very active | 1.9 |
TDEE = BMR × activity coefficient3. Goal adjustment
A biological goal factor is applied to the TDEE:
| Goal | Calorie adjustment |
|---|---|
| Lose weight | Deficit |
| Maintain | Isocaloric |
| Gain mass | Surplus |
The goal speed (set in your profile) determines the magnitude of the deficit or surplus.
4. Macro distribution
The default macronutrient targets are distributed by calorie ratio:
| Macro | % of calories | Energy (Atwater) |
|---|---|---|
| Carbs | 50% | 4 kcal/g |
| Protein | 20% | 4 kcal/g |
| Fat | 30% | 9 kcal/g |
The grams of each macro are obtained by dividing that macro's target calories by its Atwater constant. The reference calorie formula is:
kcal = 4 × Protein(g) + 4 × Carbs(g) + 9 × Fat(g)Tip
These values are the starting point. You can manually reconfigure any target — the app and MacroAI will then respect your values.
What about water?
The hydration target is tracked separately from the energy macros and has its own daily progress. Water
Rigor with AI
When a plan is generated by MacroAI, the values go through a deterministic normalization pipeline that recalculates and rebalances everything to hit the targets. See AI and automation.