Macro Calculator

Find your daily protein, carbohydrate, and fat targets based on your body metrics, activity level, and goal. Uses the Mifflin-St Jeor formula with weight-based nutrient scaling.

Estimate daily calories and macronutrients

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Calculation Examples

Calculation Case Result
Cut: male, 30 years, 85 kg, 180 cm, active Approx. 2,200 kcal: 204 g protein, 77 g fat, 173 g carbs
Maintain: female, 25 years, 60 kg, 165 cm, lightly active Approx. 1,800 kcal: 108 g protein, 54 g fat, 221 g carbs
Bulk: male, 22 years, 70 kg, 175 cm, very active Approx. 3,000 kcal: 140 g protein, 63 g fat, 468 g carbs

How to Use the Macro Calculator

Enter your gender, age, height, current weight, and activity level, then select your goal: Cut (fat loss), Maintain, or Bulk (muscle gain). Click Calculate to see your daily calorie target and gram targets for protein, fat, and carbohydrates.

The calculator works in three stages. First, it computes your Basal Metabolic Rate (BMR) using the Mifflin-St Jeor equation. Second, it multiplies BMR by your activity factor to find your Total Daily Energy Expenditure (TDEE). Third, it applies a goal modifier: a 20% calorie deficit for cutting, a 10% surplus for bulking, or no change for maintenance, with a minimum floor of 1,200 kcal/day to protect metabolic health.

Unlike calculators that apply fixed percentage splits (e.g., "30% protein"), this tool scales nutrients directly to your body weight: 2.4 g of protein per kg for cutting, 2.0 g/kg for bulking, 1.8 g/kg for maintenance, and 0.9 g of fat per kg across all goals. The remaining calories after protein and fat are allocated to carbohydrates. Weight-based scaling reflects how protein needs relate to lean mass, not total calories — the method used by registered sports dietitians.

How Your Macros Are Calculated

The Mifflin-St Jeor equation, validated in a 2005 review by the Academy of Nutrition and Dietetics as the most accurate BMR formula for the general population, is the foundation of this calculator. The formulas are: \[\text{Men: } BMR = 10 \times W + 6.25 \times H - 5 \times A + 5\] \[\text{Women: } BMR = 10 \times W + 6.25 \times H - 5 \times A - 161\] where \(W\) is weight in kg, \(H\) is height in cm, and \(A\) is age in years. TDEE is then calculated by multiplying BMR by an activity factor ranging from 1.2 (sedentary) to 1.9 (super active).

The protein-first allocation approach is grounded in sports nutrition research. A 2017 meta-analysis by Morton et al. published in the British Journal of Sports Medicine found that protein intakes above 1.62 g/kg produced no additional muscle gain on average, but higher intakes during a caloric deficit (2.3–3.1 g/kg, per Helms et al., 2014) help preserve lean mass. This calculator uses 2.4 g/kg for cutting as a practical target within that range. The 0.9 g/kg fat floor supports testosterone production, fat-soluble vitamin absorption (A, D, E, K), and essential fatty acid requirements, consistent with ACSM dietary guidelines.

Macronutrient breakdown diagram showing protein, fat, and carbohydrate gram targets for cut, maintain, and bulk goals

Useful Tips 💡

  • Recalculate every time your weight changes by 2–3 kg. As body weight decreases during a cut, TDEE drops — eating the same calories as before will eventually stall fat loss.
  • Hit your protein gram target first each day before worrying about fat and carbohydrate precision. Protein is the most metabolically important macro for both fat loss and muscle gain.
  • Choose your activity level based on your total weekly movement, not just gym sessions. A person who trains 4 days per week but sits at a desk otherwise is typically "lightly active," not "very active."

📋Steps to Calculate

  1. Enter your gender, age, height, and weight. Use kg and cm, or switch to lbs and inches.

  2. Select your activity level based on your weekly exercise frequency, not your job activity alone.

  3. Choose your goal: Cut, Maintain, or Bulk.

  4. Click Calculate to see daily targets for calories, protein, fat, and carbohydrates.

Mistakes to Avoid ⚠️

  1. Selecting "Very Active" or "Super Active" when daily life is sedentary: overestimating activity inflates TDEE and creates a calorie surplus disguised as a maintenance or deficit target.
  2. Ignoring the 1,200 kcal/day minimum floor: cutting below this threshold risks nutrient deficiencies, muscle loss, and metabolic adaptation that slows future fat loss.
  3. Mixing unit systems: entering weight in pounds but height in centimeters, or vice versa, produces an incorrect BMR. Confirm both inputs use the same system before calculating.
  4. Tracking only calorie totals and ignoring gram targets: hitting 2,000 kcal from mostly fat and little protein produces a very different body composition outcome than 2,000 kcal distributed per the calculated macro split.

Applications of Macro Tracking📊

  1. Fat loss (cut): Use the calculated protein target (2.4 g/kg) to preserve muscle during a caloric deficit and minimize the risk of metabolic adaptation.

  2. Muscle gain (bulk): Identify the precise caloric surplus and carbohydrate target needed to fuel high-intensity training and support hypertrophy without excessive fat gain.

  3. Maintenance and general health: Establish a stable daily intake that matches energy expenditure, supports hormonal function, and provides adequate micronutrient intake.

  4. Diet planning: Use the gram targets as daily limits when logging food in apps like MyFitnessPal or Cronometer to replace guesswork with measurable nutritional structure.

Questions and Answers

What is a macro calculator and how does it work?

A macro calculator computes your daily targets for the three macronutrients — protein, carbohydrates, and fat — in grams, based on your body metrics, activity level, and goal. It first estimates your Total Daily Energy Expenditure (TDEE) using the Mifflin-St Jeor equation and an activity multiplier, then allocates calories to each macronutrient using weight-based scaling rather than fixed percentage splits. The result is a personalized daily blueprint that gives you specific gram targets to hit, rather than a generic calorie number.

How is the macro calculator for weight loss different from a basic calorie counter?

A basic calorie counter tells you how many calories to eat. A macro calculator for weight loss also tells you how to distribute those calories to protect muscle during the deficit. During a caloric deficit, the body can break down muscle protein for energy — a process that slows metabolism and reduces long-term fat loss. This calculator assigns 2.4 g of protein per kg of body weight during a cut, a level supported by research (Helms et al., 2014, International Journal of Sport Nutrition and Exercise Metabolism) to minimize muscle loss while maximizing fat oxidation.

Why does the macro calculator use different values for men and women?

The Mifflin-St Jeor equation includes a gender constant: +5 for men and -161 for women. This adjustment reflects the average difference in lean mass and basal metabolic rate between sexes at equivalent body weights. Women typically have a higher proportion of fat mass relative to lean mass, which is metabolically less active, resulting in a lower BMR per kilogram of total body weight. Using a gender-neutral formula consistently overestimates calorie needs for most women, leading to a caloric surplus rather than the intended deficit or maintenance.

How often should I recalculate my macros?

Recalculate every time your weight changes by approximately 2–3 kg (4–6 lbs). TDEE is proportional to body weight — a lighter body requires fewer calories to sustain. If you lose 5 kg during a cut and do not recalculate, your original deficit shrinks as your TDEE decreases, and fat loss will eventually plateau. Regular recalculation keeps the deficit accurate relative to your current body composition.

Can I use this as a keto macro calculator?

Yes, with a manual adjustment. The calculator provides your total calorie and protein targets, which remain valid for ketogenic diets. For keto, cap carbohydrates at 20–50 g/day and redistribute those calories to fat. The protein target from this calculator is still the correct starting point: too little protein on keto accelerates muscle loss, while too much can be converted to glucose (gluconeogenesis) and interfere with ketosis. Adjust fat upward to fill remaining calories after protein and capped carbs are accounted for.

Why does the macro calculator for muscle gain allocate so many calories to carbohydrates?

After protein and fat minimums are met, remaining calories go to carbohydrates because carbohydrates are the primary fuel source for high-intensity resistance training. During a bulk, total calorie intake is above maintenance, creating a surplus that is largely allocated to carbohydrates. Muscle glycogen — stored carbohydrate — is the dominant energy substrate for sets performed above 70% of one-repetition maximum (Burke et al., 2011, Journal of Sports Sciences). Adequate carbohydrate intake also stimulates insulin release, which aids amino acid transport into muscle cells and supports post-workout recovery.

What makes this macro calculator more accurate than fixed-percentage tools?

Fixed-percentage macro calculators (e.g., "30% protein, 40% carbs, 30% fat") produce protein targets that scale with total calories rather than with body weight. At very low calorie intakes (1,200 kcal), 30% protein is only 90 g — inadequate for a 75 kg person trying to preserve muscle. At very high intakes (4,000 kcal), 30% protein is 300 g — more than necessary and displacing carbohydrates that would better fuel training. Weight-based scaling (g per kg of body weight) keeps protein and fat in a physiologically appropriate range regardless of total calorie level, which is the approach used in clinical sports nutrition practice.

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Disclaimer: This calculator is designed to provide helpful estimates for informational purposes. While we strive for accuracy, financial (or medical) results can vary based on local laws and individual circumstances. We recommend consulting with a professional advisor for critical decisions.