What is Macro Calculator?

Estimates your daily protein, carb, and fat needs based on your body stats, activity level, and fitness goal. Pick your goal and get a macro split tailored to cutting, maintaining, or bulking.

The tool uses the Mifflin–St Jeor equation to estimate basal metabolic rate, multiplies by an activity factor (1.2 to 1.9) for total daily energy expenditure, then applies a goal adjustment scaled by your chosen pace (a Moderate cut subtracts 500 kcal, a Moderate bulk adds 300, with Mild and Aggressive smaller or larger). If you lift weights, protein is nudged up and tapered slightly by training experience. Macro splits default to 35/40/25 (cut), 30/40/30 (maintain), and 30/45/25 (gain), and every number stays above a 1,200 kcal safety floor.

How to use

1. Enter your weight, height, age, and gender, then select your activity level from sedentary to very active.
2. Choose your goal (lose weight, maintain, or gain muscle) and the calculator adjusts your total calories and macro split.
3. Review your daily targets in grams for protein, carbs, and fat, plus the calorie breakdown for each macronutrient.

When to use

• Setting up a starting point before tracking food in MyFitnessPal or Cronometer.
• Adjusting macros when you move from cutting to maintenance after hitting goal weight.
• Planning a meal-prep day around protein, carb, and fat grams instead of just calories.

Result

A 28-year-old male, 180 lbs, 5'10", moderately active, wants to lose weight. The calculator recommends 2,100 calories: 180g protein (34%), 210g carbs (40%), 60g fat (26%) — a high-protein deficit plan to preserve muscle.

FAQ

Which BMR formula does the calculator use, and why?

Mifflin–St Jeor (1990), the formula most major studies treat as the most accurate for the general adult population. It's typically within 10% of true measured BMR. Harris–Benedict, an older formula, tends to overestimate slightly.

What does the Mild, Moderate, or Aggressive pace change?

It sets the size of your daily calorie offset. A cut runs at about 250, 500, or 750 kcal below maintenance; a bulk at about 150, 300, or 500 above. Moderate (the 500 kcal cut) is the sweet spot most coaches use, since it loses roughly 0.45 kg (1 lb) of fat a week while protecting muscle. Aggressive moves the scale faster but brings more fatigue and muscle-loss risk, so total intake never drops below a 1,200 kcal floor.

Why is the cutting protein at 35% when many sites suggest 40%?

35% protein at a moderate deficit typically lands around 2.0 to 2.4 g/kg of body weight, which research shows is enough to preserve muscle. Going higher is fine but isn't required and crowds out carbs, which fuel lifts. Bump protein toward 40% if you're in a steep deficit or older.

Do I really need 1.9x activity multiplier if I work out daily?

Probably not. 1.9x is reserved for physical-labour jobs (construction, landscaping, farming) on top of training. A desk worker who lifts 5 days a week is closer to 1.55 to 1.6. Overestimating activity is the most common reason cuts stall.

How often should I recalculate?

Every 4 to 6 kg (10 lb) of weight change, since calorie needs shift with body mass. Also recalculate after a long break from training (activity multiplier drops) or after a steady plateau of 2 to 3 weeks at the same scale weight.

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