Estimate how many grams of protein, carbohydrates, and fat to eat each day from your age, sex, height, weight, activity, and goal. Switch US and metric units, pick a plan (Balanced, Low Fat, Low Carb, High Protein, or a custom split), and see calories, kilojoules, guideline ranges, plus sugar and saturated-fat limits.
Formula
Calories start with basal metabolic rate (BMR), then activity and a weight goal. Mifflin St Jeor (the default) uses kilograms (W), centimetres (H), and years (A). Katch-McArdle uses lean mass from body-fat fraction (bf):
Men: BMR = 10W + 6.25H − 5A + 5
Women: BMR = 10W + 6.25H − 5A − 161
Katch: BMR = 370 + 21.6 × W × (1 − bf)
Calories = round(BMR × activity + goal)
kJ = round(calories × 4.1868)
Goal adjustments assume about 3,500 calories per pound: 0 (maintain), ±250 (0.5 lb / 0.25 kg per week), ±500 (1 lb / 0.5 kg), ±1,000 (2 lb / 1 kg).
Each plan assigns a percentage of those calories to protein, carbs, and fat.
Grams are round(calorie share ÷ kcal per gram) with 4.1 / 3.75 / 8.8 kcal/g.
| Plan | Protein | Carbs | Fat |
|---|---|---|---|
| Balanced | 25% | 50% | 25% |
| Low Fat | 27.5% | 52.5% | 20% |
| Low Carb | 30% | 40% | 30% |
| High Protein | 35% | 42.5% | 22.5% |
| Activity level | Factor |
|---|---|
| Basal Metabolic Rate (BMR) | 1.0 |
| Sedentary (little or no exercise) | 1.2 |
| Light (1–3 times/week) | 1.375 |
| Moderate (4–5 times/week) | 1.465 |
| Active (daily, or intense 3–4 times/week) | 1.55 |
| Very Active (intense 6–7 times/week) | 1.725 |
| Extra Active (very intense daily, or physical job) | 1.9 |
Sugar limit = round(Balanced carb grams × 0.2). Saturated fat limit = round(Balanced fat grams × 0.4).
These numbers are typical-situation estimates. If you are an athlete, pregnant, or on a medical diet, ask a doctor or registered dietitian before changing how you eat. Very low calorie intakes should only be used under medical supervision.
Exercise here means 15–30 minutes of elevated heart rate. Intense exercise is 45–120 minutes; very intense is 2+ hours.
What are macronutrients?
Protein, carbohydrate, and fat are the bulk energy nutrients. Protein supplies essential amino acids (from meat, dairy, beans, nuts, and seeds). Carbohydrates cover sugars, starches, and fiber; complex sources (vegetables, fruit, whole grains, legumes) are the usual priority over added sugar. Fat is the densest energy store and is needed for cell membranes and fat-soluble vitamins — unsaturated fats are generally preferred, trans fats avoided, and saturated fat kept under about 10% of calories in U.S. dietary guidance.
Micronutrients (vitamins and minerals) matter too, but they are needed in milligrams, not tens of grams, and are not totaled here.
Macronutrients in common foods
| Food | Serving | Protein | Carbs | Fat |
|---|---|---|---|---|
| Apple | 1 (4 oz.) | 0.3 g | 14.4 g | 0.2 g |
| Banana | 1 (6 oz.) | 1.9 g | 38.9 g | 0.6 g |
| Broccoli | 1 cup | 2.6 g | 6.0 g | 0.3 g |
| Chicken, cooked | 2 oz. | 16 g | 0 g | 1.8 g |
| Egg | 1 large | 6.3 g | 0.4 g | 5.0 g |
| Rice, cooked | 1 cup | 4.2 g | 44.1 g | 0.4 g |
| Milk (2%) | 1 cup | 8.1 g | 11.4 g | 4.8 g |
| Greek yogurt (low-fat) | 1 cup | 12.9 g | 17.3 g | 3.8 g |
Examples
Man, 25, 5 ft 10 in, 165 lb, moderate, maintain
Mifflin St Jeor at moderate activity (1.465) is 2,549 Calories/day (10,672 kJ). Balanced macros are 155 g protein, 340 g carbs, 72 g fat, with ranges 75–218 / 272–462 / 58–101 g, sugar under 68 g, and saturated fat under 29 g. Low Fat is 171/357/58, Low Carb 187/272/87, and High Protein 218/289/65.
Woman, 30, 5 ft 4 in, 140 lb, light activity, mild loss
Female Mifflin at light activity (1.375) minus 250 calories is 1,593 Calories/day (6,670 kJ). Balanced macros are 97 g protein, 212 g carbs, 45 g fat.
Metric default, 180 cm, 65 kg
The same age-25 male at moderate activity in metric units is 2,425 Calories/day, Balanced 148 / 323 / 69 g.