A macro calculator estimates your daily calories and splits them into grams of protein, carbohydrate and fat. Formula: BMR = 10w + 6.25h – 5age + 5 (male) or -161 (female). TDEE = BMR x activity; lose -500 / gain +300. Protein = 1.8w g; fat = 25% of TDEE / 9; carbs = remaining kcal / 4. A moderately active 70 kg, 175 cm, 30-year-old man needs about 2,556 calories: 126 g protein, 353 g carbs and 71 g fat.
On this page
How to use the macro calculator
- Enter weight, height, age and sex.
- Choose your activity level and goal.
- Read calories and grams of protein, carbs and fat.
How the macro calculator works
The macro calculator estimates your daily calories, then splits them into protein, carbohydrate and fat in grams. It works in four steps:
- BMR with the Mifflin-St Jeor equation: 10 × kg + 6.25 × cm − 5 × age + 5 for men, or − 161 for women
- Calories = BMR × activity factor, then − 500 to lose or + 300 to gain
- Protein = 1.8 g per kg of body weight; fat = 25% of calories ÷ 9
- Carbs = the remaining calories ÷ 4
Macro calculator worked example
A 30-year-old man who weighs 70 kg and is 175 cm tall has a BMR of 10 × 70 + 6.25 × 175 − 150 + 5 = 1,649 calories. Moderately active (× 1.55), he needs about 2,556 calories to maintain weight. The macro calculator sets protein at 126 g (504 calories), fat at 25% or 71 g (639 calories), and the rest, 353 g, as carbohydrate.
| Person | Activity | Goal | Calories | Protein g | Carbs g | Fat g |
|---|---|---|---|---|---|---|
| Man, 70 kg, 175 cm, 30 | Moderate | Maintain | 2,556 | 126 | 353 | 71 |
| Man, 70 kg, 175 cm, 30 | Moderate | Gain | 2,856 | 126 | 409 | 79 |
| Man, 80 kg, 180 cm, 40 | Moderate | Lose | 2,182 | 144 | 265 | 61 |
| Woman, 60 kg, 165 cm, 30 | Light | Maintain | 1,815 | 108 | 232 | 50 |
How the split compares with guidelines
The National Academies’ Dietary Reference Intakes set acceptable ranges for adults of 45% to 65% of calories from carbohydrate, 20% to 35% from fat and 10% to 35% from protein. In the example, carbs are 55%, fat 25% and protein 20%, all inside the ranges. The protein RDA is 0.8 g per kg; the macro calculator uses 1.8 g per kg, a higher level often chosen by active people and those trying to keep muscle while losing weight.
Choosing an activity level
The activity factor multiplies BMR to account for movement and exercise: about 1.2 for desk work and little exercise, 1.375 for light exercise, 1.55 for moderate exercise three to five days a week and higher for hard daily training. Most people overestimate activity, so start lower and adjust after two or three weeks based on how your weight actually changes.
Tips
- A 500-calorie daily deficit is a common starting point for gradual loss.
- Spread protein across meals.
- Choose mostly whole grains, fruit, vegetables, beans and lean proteins, as the Dietary Guidelines suggest.
For general information only, not medical or nutrition advice. A doctor or registered dietitian can give advice for your health and goals.
Adjusting your macros over time
The numbers are a starting estimate. Weigh yourself a few times a week at the same time of day and compare two-week averages. If you are losing more than about 1% of body weight a week, add 100 to 200 calories, mostly from carbohydrate. If nothing changes after three weeks, take away a similar amount. Re-run the macro calculator after every 4 to 5 kg of change, because a lighter body needs fewer calories.
Food labels list protein, carbohydrate and fat in grams per serving, and the FDA’s Nutrition Facts label uses 2,000 calories a day as a general reference. Tracking food for a week or two shows how close your normal eating is to the targets. You do not need to be exact every day; being close on average is what moves results. Drink enough water and include fiber-rich foods.
Related converters and calculators
Related calculators:
- TDEE calculator: daily calories
- BMR calculator: resting calories
- Protein calculator: protein
- Carbohydrate calculator: carbs
Sources
Mifflin MD, St Jeor ST et al. A new predictive equation for resting energy expenditure in healthy individuals. Am J Clin Nutr 1990; National Academies: Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids; Dietary Guidelines for Americans, 2025–2030.
Formula and method
Calories = BMR × activity (−500 to lose, +300 to gain). Protein = 1.8 × kg. Fat = 25% of calories ÷ 9. Carbs = (calories − protein × 4 − fat × 9) ÷ 4.
Metric weight (kg) and height (cm). Activity is a multiplier. Macro split is a fixed sketch, not individualized medical nutrition therapy.
Questions about this calculator
What formula does it use?
Mifflin-St Jeor for BMR.
How much protein does it set?
1.8 g per kg of body weight.
What share is fat?
25% of calories.
How big is the deficit to lose weight?
500 calories a day.
Are carbs fixed?
No, carbs take the remaining calories.
Check the assumptions and units before relying on a result. Financial, tax and health estimates do not replace advice for your individual circumstances.
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