Macronutrients — protein, carbohydrates, and fat — make up the calories in everything you eat, and getting the right balance can make a huge difference for energy, body composition, and athletic performance. This macro calculator estimates your daily calorie needs using the Mifflin-St Jeor equation, then converts that calorie target into personalized protein, carbohydrate, and fat gram goals based on your activity level, fitness goal, and dietary preferences.
It’s designed for anyone from beginners learning to track meals to experienced lifters planning a cut or bulk. Simply enter your details, choose your activity level and goal, and the tool returns a full daily macro breakdown — including per-meal suggestions. Use it as a starting point, then adjust based on your hunger, energy, and weekly scale trends.
How to Use This Calculator
Enter your age, height, and weight in either metric or imperial units; the tool converts automatically. Choose an activity level that reflects your typical week — most desk workers who train two to three times should select Light rather than Moderate. Then pick a goal: the cut and bulk options apply a sensible percentage to your maintenance calories, and you can fine-tune with the dropdown after using the quick buttons. Set a protein target that matches your training volume, choose how much of your calories should come from fat, and select your usual meals per day. Press Calculate Macros to see BMR, TDEE, target calories, daily gram targets, and per-meal portions.
The Formula Behind It
This calculator uses the Mifflin-St Jeor equation to estimate basal metabolic rate:
- Men: BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age + 5
- Women: BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age − 161
Total daily energy expenditure (TDEE) = BMR × activity multiplier:
| Activity Level | Multiplier |
|---|---|
| Sedentary — little or no exercise | 1.2 |
| Light — exercise 1–3 days/week | 1.375 |
| Moderate — exercise 3–5 days/week | 1.55 |
| Active — exercise 6–7 days/week | 1.725 |
| Very active — physical job or intense training | 1.9 |
Goal calories = TDEE × your selected percentage. Protein is set from body weight, fat is a percentage of total calories, and carbohydrate calories fill the remainder. Since protein and carbs provide 4 kcal/g and fat provides 9 kcal/g, the tool converts calories into grams. See the Mifflin-St Jeor equation article on Wikipedia for more background.
Worked Example
A 32-year-old woman who is 165 cm, 62 kg, moderately active, and maintaining weight has BMR = 10×62 + 6.25×165 − 5×32 − 161 ≈ 1,330 kcal. Her TDEE is 1,330 × 1.55 ≈ 2,062 kcal.
Protein (standard): 1.6 × 62 ≈ 99 g → 396 kcal
Fat (25%): 0.25 × 2,062 ≈ 516 kcal → 57 g
Carbs: 2,062 − 396 − 516 ≈ 1,150 kcal → 288 g
Over 3 meals: ~33 g protein, 19 g fat, 96 g carbs per meal.
If the same person chose a 20% cut, her calories would drop to about 1,650 kcal, protein would stay high, and carb grams would be the main variable to change.
Choosing the Right Macro Split
Protein should remain moderately high — especially during a cut — to preserve lean mass, so the calculator uses 1.6 to 2.2 g per kg. Fat at 20–30% of calories supports hormones and satiety, while carbohydrates provide flexible energy for training. Endurance athletes can set fat lower and rely more on carbs; people who feel better on low-carb eating can choose the higher-fat setting. The best split is the one you can follow consistently while meeting protein needs.
Common Mistakes to Avoid
- Overestimating activity. An inflated multiplier can add 300–500 calories to your target and stall fat loss.
- Cutting protein too low. Protein protects muscle mass while you are in a deficit.
- Ignoring food quality. Whole foods make hitting macros easier and support health.
- Forgetting to recalculate. Re-run the calculator every 4–6 weeks or after a 4–5 kg change.
- Chasing perfection. Consistent week-to-week averages matter more than hitting every gram on every meal.
Frequently Asked Questions
Are these numbers exact? No. They are validated estimates, but individual metabolism varies by 5–10%. Use the output for two to three weeks, then adjust based on your weight trend, hunger, and energy.
Do macros change on rest days? Some people shift carbohydrates toward training days and keep protein and fat constant. The daily average remains a good reference.
Is low-carb necessary? No. The fat setting lets you create a lower-carb or higher-carb plan; consistency and protein intake matter more than a specific ratio.
When should I recalculate? After a 4–5 kg change, after significant training changes, or every 4–6 weeks.
How do I track fiber with macros? Fiber is a carbohydrate subtype; a separate target can help. Use this fiber calculator to set a fiber goal based on your calorie intake and gender.