Get your personalized daily protein, carbs & fat targets — calculated with Mifflin-St Jeor and TDEE. Free, no sign-up.
Macronutrients — or macros — are the three nutrients your body needs in large quantities to fuel every function. Unlike micronutrients (vitamins and minerals), macros provide the energy (calories) your body runs on:
Tracking macros goes beyond simply counting calories. Two people eating 2,000 kcal/day can have radically different body composition outcomes depending on how those calories are split between protein, carbs and fat.
This calculator uses two established methods combined:
The Mifflin-St Jeor equation (1990) is considered the gold standard for BMR estimation in healthy adults, with a mean error of roughly ±10% compared to indirect calorimetry. Your TDEE is then adjusted for your goal: a 500 kcal/day deficit for fat loss (targeting approximately 0.5 kg/week of fat loss), maintenance for body recomposition, or a 250 kcal/day surplus for lean muscle gain.
| Activity Level | Multiplier | Who it suits |
|---|---|---|
| Sedentary | 1.2× | Desk job, no planned exercise |
| Lightly active | 1.375× | Walking, light exercise 1–3 days/week |
| Moderately active | 1.55× | Gym or sport 3–5 days/week |
| Very active | 1.725× | Hard training 6–7 days/week |
| Extra active | 1.9× | Athlete training 2×/day or physical labor |
Most people underestimate their activity level. If you work a desk job but train 4 times a week, “moderately active” is usually the right fit. When in doubt, choose a lower multiplier and add 100 kcal if you stop losing weight after 2–3 weeks.
The 30% protein / 40% carbs / 30% fat split is a well-rounded starting ratio backed by decades of research:
If you follow a specific diet style (keto, low-fat, high-protein), you can adjust manually once you have your total calorie target. The most important variable for body weight is total calories; the most important variable for body composition is protein intake.
Macros (macronutrients) are the three main nutrient categories: protein (4 kcal/g), carbohydrates (4 kcal/g) and fat (9 kcal/g). Tracking macros gives you control over body composition beyond just counting total calories.
It uses the Mifflin-St Jeor equation to estimate your BMR, multiplies by your activity factor to get TDEE, adjusts for your goal (deficit/maintenance/surplus), then splits calories 30/40/30 across protein, carbs and fat.
Research supports 1.6–2.2 g per kg of body weight for active individuals. This calculator’s 30% protein split typically lands in that range. Sedentary adults can do well on as little as 0.8 g/kg.
Tracking macros gives more control over body composition. Start with calories if you’re new to tracking, then add macro targets once you’re comfortable. The most impactful lever for most people is ensuring adequate protein intake.
TDEE (Total Daily Energy Expenditure) is the total calories your body burns in a day, including exercise and non-exercise activity. Eating at your TDEE maintains your weight. Eating below it creates a deficit for fat loss.
The Mifflin-St Jeor equation has a mean error of ±10%. Use the output as a starting point, track for 2–3 weeks, and adjust by 100–200 kcal if your weight isn’t moving as expected.