Calculators / Macro calculator
Macro calculator
A macro calculator turns sex, age, height, weight and activity into a daily calorie target and the grams of protein, fat and carbohydrate that make it up. This one runs the MacroDiet v2 algorithm unchanged and prints the arithmetic under every result.
Also on macrodiet.fit in six languages — same formula, same numbers.
How the math works
Four steps, the same code MacroDiet runs, in order:
- BMR — Mifflin-St Jeor: 10 × kg + 6.25 × cm − 5 × age + 5 for men, − 161 instead of + 5 for women. Example: 850 + 1,125 − 150 + 5 = 1,830.
- TDEE — round(BMR × multiplier). The activity level maps onto two inputs, training days per week and daily movement, and the multiplier is their sum (table below). Example: 1,830 × 1.55 = 2,837.
- Target — maintain is TDEE. Lose or gain converts a weekly rate to a daily change: kg × rate% × 7,700 ÷ 7, capped at 35% of TDEE. On a cut the target is then held at a calorie floor (1,500 kcal men / 1,200 kcal women; a lower 1,200 / 1,000 mode exists). Example, moderate cut: 85 × 0.5% × 7,700 ÷ 7 = 467 → 2,370 kcal.
- Split — protein kg × tier (+0.2 on a cut; capped at 50% of calories); fat = (target − protein kcal) × style%, floored at max(0.6 g/kg, 20% kcal); carbohydrate = whatever is left ÷ 4. Keto fixes carbohydrate at 30 g and lets fat balance instead.
Activity levels and their multipliers
| Level | Training days / week | Daily movement | Multiplier |
|---|---|---|---|
| Sedentary (little or no exercise) | 0 | sedentary | × 1.15 |
| Lightly active (1–3 days/week) | 1-3 | sedentary | × 1.325 |
| Moderately active (3–5 days/week) | 4-6 | moderate | × 1.55 |
| Very active (6–7 days/week) | 7+ | very active | × 1.825 |
| Extra active (2× per day or physical job) | 7+ | very active | × 1.825 |
The two top levels resolve to the same v2 inputs (7+ days, very active) and therefore the same multiplier — that is the source algorithm's behaviour, kept so the numbers here match macrodiet.fit exactly. Multipliers: training days {0: 1.2, 1–3: 1.375, 4–6: 1.55, 7+: 1.725} plus daily movement {sedentary −0.05, moderate 0, very active +0.1}.
What the numbers are not
Mifflin-St Jeor is a population equation: for an individual it can be a few hundred kcal off in either direction, and 7,700 kcal per kg is a convention, not a measurement of anyone's tissue. Treat the output as a starting estimate to check against the weight trend over weeks — which is what MacroDiet does — and treat the floors and caps as the algorithm's guardrails, not as medical thresholds. This is arithmetic, not medical advice.
Frequently asked
What are macronutrients?
Protein, fat and carbohydrate — the three nutrients that carry energy. The calculator counts them at 4, 9 and 4 kcal per gram, so a macro target is just a calorie target split three ways: for the 2,837 kcal example that is 136 g protein (544 kcal), 89 g fat (801 kcal) and 373 g carbohydrate (1,492 kcal).
How are macros calculated?
In four steps. Mifflin-St Jeor gives BMR (1,830 kcal here); an activity multiplier gives TDEE (× 1.55 = 2,837); the goal moves the target up or down by a weekly rate converted to kcal per day; then protein is set from body weight, fat as a share of what is left, and carbohydrate fills the remainder. Every step is printed under the result.
How many macros do I need to lose fat?
The calculator's "lose" setting takes a weekly rate of 0.3%, 0.5% or 0.75% of body weight, converts it at 7,700 kcal per kg (85 kg at the moderate rate is 467 kcal/day, target 2,370 kcal), adds 0.2 g/kg to the protein tier (153 g) and keeps fat at 35% of the remaining calories on the balanced style (68 g), leaving 287 g carbohydrate. That is the algorithm's output for the example, not a prescription — the rate, cap and floors are described below.
How much protein do I need per kg of body weight?
The calculator offers four tiers — 1.2, 1.6, 2 and 2.4 g per kg of body weight — and adds 0.2 g/kg when the goal is to lose. At 85 kg the moderate tier is 136 g a day; the same tier on a cut is 153 g. The algorithm warns above 3 g/kg and never lets protein take more than half the calories. Which tier suits a person is a coaching question, not something the arithmetic decides.
What is the minimum fat intake the calculator allows?
Fat is set as a share of the calories left after protein (20% low fat, 35% balanced, 50% low carb, 70% keto) and then held to a floor of whichever is larger: 0.6 g per kg of body weight or 20% of total calories. For the example that floor is 63 g, so the low-fat style cannot push fat below it. The floor is an algorithm rule so the split stays coherent; it is not a health recommendation.
Do macros change with activity level?
Yes, through the multiplier. The same 85 kg example at "sedentary" (× 1.15) has a TDEE of 2,105 kcal instead of 2,837; protein stays at 136 g because it is set from body weight, so fat drops to 61 g and carbohydrate to 253 g. In other words activity changes total calories and, because protein is fixed in grams, the percentages shift too.
Should I track macros for muscle gain?
Whether to track is a personal choice; what the calculator does on "gain" is add the same rate-based surplus it would subtract on a cut — 85 kg at the moderate rate is +468 kcal/day, target 3,305 kcal — capped at 35% of TDEE, with the protein tier unchanged (no +0.2 bump on a gain). MacroDiet then logs food against that target so you can see whether the surplus is actually being eaten.
Related calculators
Track against these targets
MacroDiet's own calculators run this exact v2 formula, and the same zyra-algo engine sets the targets inside the app — where logged food is compared against them and the dashboard shows the weight trend. Web app, live at macrodiet.fit — nothing to install.
Zyra is a training and nutrition tracking tool. Nothing on this page is medical advice, a diagnosis, or an individual prescription. The numbers are estimates from published formulas and the apps' own rules — consult a qualified professional for decisions about your health, and a coach for your training.