How this macro calculator works
Your macros are set in three steps: estimate the calories you burn, adjust for your goal, then split the result into grams. The burn estimate uses the Mifflin-St Jeor equation, published in the American Journal of Clinical Nutrition in 1990 and still the standard recommendation for the general population:
- Men: BMR = 10 × weight (kg) + 6.25 × height (cm) − 5 × age + 5
- Women: BMR = 10 × weight (kg) + 6.25 × height (cm) − 5 × age − 161
BMR is what you burn at rest — the BMR calculator covers it on its own. An activity factor between 1.2 (sedentary) and 1.9 (extra active) scales it up to your total daily energy expenditure; the TDEE calculator explains those multipliers in detail. Your goal then shifts the calories: 500 below maintenance to lose about 0.5 kg (1 lb) per week, 250 above to gain slowly.
From calories to grams: the 4/4/9 rule
Each macro carries a fixed amount of energy: protein 4 calories per gram, carbohydrate 4, fat 9. The calculator multiplies your calorie target by each preset percentage, then divides by the calories per gram. A worked example: a 30-year-old woman, 165 cm and 65 kg, moderately active, has a BMR of 1,370 kcal and a TDEE near 2,124. Cutting 500 leaves 1,624 kcal a day. On the balanced preset that is 122 g protein, 162 g carbs, and 54 g fat.
What are macros?
Macronutrients are the three nutrients your body needs in large amounts. Everything you eat is some mix of them, and together they account for every calorie on your plate.
Protein (4 kcal per gram)
Protein builds and repairs muscle and is the most filling macro per calorie, which is why every preset here holds it at 30% or higher. Meat, fish, eggs, dairy, tofu, and legumes are the dense sources. For a target based on body weight rather than calories, use the protein calculator.
Carbohydrates (4 kcal per gram)
Carbs are your main training fuel and the brain’s preferred energy source. Whole-food carbs such as oats, rice, potatoes, and fruit also carry the fiber that keeps digestion and appetite steady. Carbs are the flexible macro: the presets range from 40% down to 5%.
Fat (9 kcal per gram)
Fat supports hormone production and lets you absorb vitamins A, D, E, and K. Because it packs 9 calories into each gram, small portions move your totals fast. Holding fat under about 20% of calories for long stretches is a bad idea for most people.
How to choose your macro split
At equal calories, every split below produces a similar result on the scale — total intake decides that. The split changes how full you feel, how you perform, and what kinds of meals fit your day. Here is each preset at 2,000 kcal:
| Preset | Protein / carbs / fat | Protein | Carbs | Fat |
|---|---|---|---|---|
| Balanced | 30 / 40 / 30 | 150 g | 200 g | 67 g |
| Low-carb | 40 / 20 / 40 | 200 g | 100 g | 89 g |
| High-protein | 40 / 35 / 25 | 200 g | 175 g | 56 g |
| Keto | 30 / 5 / 65 | 150 g | 25 g | 144 g |
Balanced (30/40/30)
The default. Enough protein to hold muscle, enough carbs to train well. If you have no strong preference, start here.
Low-carb (40/20/40)
Fewer carbs, more fat and protein. Some people find appetite easier to manage this way. It does not burn more fat at equal calories, so pick it for preference, for how it feels.
High-protein (40/35/25)
The dieting split: maximum satiety and muscle retention while calories are low. Hitting 40% protein takes planning — expect a protein source at every meal.
Keto (30/5/65)
Carbs drop to 5%, about 25 g at 2,000 kcal, and fat covers most of your energy. If you have diabetes or take medication, talk to your doctor before starting keto; the carb change can affect blood sugar and dosing.
Macros for your goal
Weight loss
Set protein first and let the deficit do the work. The lose option here cuts 500 kcal, roughly 0.5 kg (1 lb) per week. To size the deficit yourself or see a goal date, the calorie deficit calculator handles that side.
Muscle gain
The gain option adds 250 kcal over maintenance. Small surpluses build muscle with little fat; large ones mostly add fat. Keep protein near 1.6–2.2 g per kg and train with progressively heavier loads.
Maintenance
Eating at maintenance is the skill most dieters skip: it is how results survive after a cut. The maintenance calorie calculator is built for exactly that phase. Whatever the goal, recalculate your macros after about 5 kg (10 lb) of weight change or a two-to-three-week stall.
How to hit your macros
Within about 5 g of each target counts as on plan; nobody lands exact numbers every day. Prioritize protein when you cannot hit all three, and judge yourself on the weekly average rather than any single day. Weigh the dense foods — oils, nut butters, cheese — for a week or two, since they cause most silent overshoots. Tracking is the whole game here, and logging meals in Joules turns these three targets into a running daily count.
