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Macro Calculator

Calculate your daily protein, carbohydrates & fat targets — powered by TDEE + Mifflin-St Jeor

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Formulas Used

BMR (Mifflin, Male)
= (10 × kg) + (6.25 × cm) − (5 × age) + 5
BMR (Mifflin, Female)
= (10 × kg) + (6.25 × cm) − (5 × age) − 161
TDEE = BMR × Activity Factor
Protein (g) = Cals × % ÷ 4
Carbs (g) = Cals × % ÷ 4
Fat (g) = Cals × % ÷ 9

Katch-McArdle: BMR = 370 + 21.6 × Lean Mass (kg)  |  Harris-Benedict (M): 88.362 + 13.397×kg + 4.799×cm − 5.677×age

Worked Examples

Weight Loss

80 kg Male, 178 cm, 32 yr, Moderately Active

BMR = (10×80) + (6.25×178) − (5×32) + 5
BMR = 800 + 1112.5 − 160 + 5 = 1,757 kcal
TDEE = 1,757 × 1.55 = 2,724 kcal
Target = 2,724 − 500 = 2,224 kcal
Protein167g (30%)
Carbs222g (40%)
Fat74g (30%)
Muscle Gain

60 kg Female, 163 cm, 26 yr, Very Active

BMR = (10×60) + (6.25×163) − (5×26) − 161
BMR = 600 + 1018.75 − 130 − 161 = 1,328 kcal
TDEE = 1,328 × 1.725 = 2,290 kcal
Target = 2,290 + 250 = 2,540 kcal
Protein (High-Protein)254g (40%)
Carbs222g (35%)
Fat71g (25%)
Athletic Maintenance

75 kg Male, 180 cm, 24 yr, Very Active

BMR = (10×75) + (6.25×180) − (5×24) + 5
BMR = 750 + 1125 − 120 + 5 = 1,760 kcal
TDEE = 1,760 × 1.725 = 3,036 kcal
Target = 3,036 kcal (maintain)
Protein (Athletic)190g (25%)
Carbs418g (55%)
Fat68g (20%)

What is a Macro Calculator?

A macro calculator — short for macronutrient calculator — determines how many grams of protein, carbohydrates, and fat you should eat each day to meet your specific health or fitness goal. Unlike a simple calorie counter, a macro calculator tells you what to eat, not just how much. Hitting the right macro targets is the foundation of evidence-based nutrition, used by athletes, physique competitors, and anyone seeking sustainable body composition changes.

This calculator first estimates your Total Daily Energy Expenditure (TDEE) using the Mifflin-St Jeor BMR equation — the most validated formula for general populations — then adjusts calories up or down based on your goal, and finally splits those calories into protein, carb, and fat grams using your chosen macro ratio.

How Are Macros Calculated?

Step 1 — Basal Metabolic Rate (BMR)

BMR is the number of calories your body burns at complete rest to keep organs functioning. The Mifflin-St Jeor equation (1990) is the most accurate general-purpose formula:

SexFormula
Male(10 × kg) + (6.25 × cm) − (5 × age) + 5
Female(10 × kg) + (6.25 × cm) − (5 × age) − 161

Step 2 — Total Daily Energy Expenditure (TDEE)

TDEE = BMR × Activity Factor. Activity factors range from 1.2 (sedentary desk worker) to 1.9 (extremely active person with a physical job plus daily intense training). The multiplier accounts for all calories burned through movement, digestion, and non-exercise activity.

Step 3 — Goal Adjustment

Your calorie target is adjusted from TDEE based on your goal: −500 kcal/day for fast fat loss, −250 kcal/day for slow fat loss, 0 for maintenance, +250 kcal/day for slow muscle gain, or +500 kcal/day for aggressive bulking. A deficit of 500 kcal/day produces roughly 0.5 kg of fat loss per week.

Step 4 — Macro Split

Your calorie target is then divided into grams of each macronutrient. Protein and carbohydrates each provide 4 kcal per gram; fat provides 9 kcal per gram. For example, if your target is 2,000 kcal and you use a 30/40/30 split:

  • Protein: 2,000 × 30% ÷ 4 = 150 g/day
  • Carbs: 2,000 × 40% ÷ 4 = 200 g/day
  • Fat: 2,000 × 30% ÷ 9 = 66.7 g/day

Which Macro Split Should I Choose?

PresetProteinCarbsFatBest For
Standard30%40%30%General health & balanced dieting
High Protein40%35%25%Muscle building or cutting with muscle retention
Low Carb / Keto30%10%60%Ketogenic diet, insulin sensitivity, fat adaptation
High Carb Athletic25%55%20%Endurance athletes, runners, cyclists
Balanced25%50%25%Everyday active individuals, maintainers

How Much Protein Do I Actually Need?

The minimum for general health is 0.8 g/kg/day. For body composition goals, research consistently supports 1.6–2.2 g/kg/day of lean body mass for muscle building and preservation during fat loss. A 70 kg person aiming to build muscle should target roughly 112–154 g of protein per day. Higher protein intake also increases satiety, which helps with adherence to a calorie deficit.

Frequently Asked Questions

What are macros (macronutrients)?
Macronutrients — commonly called "macros" — are the three main categories of nutrients your body uses for energy: protein, carbohydrates, and fat. Protein provides 4 kcal per gram and is essential for muscle repair and growth. Carbohydrates provide 4 kcal per gram and are the body's preferred energy source. Fat provides 9 kcal per gram and supports hormone production, vitamin absorption, and cell function. Tracking macros lets you control body composition beyond simple calorie counting.
How does this macro calculator work?
The calculator uses a three-step process. First, it calculates your Basal Metabolic Rate (BMR) — the calories your body burns at rest — using the Mifflin-St Jeor equation. Second, it multiplies your BMR by an activity factor to find your Total Daily Energy Expenditure (TDEE). Third, it adjusts your TDEE up or down based on your goal, then splits the resulting calorie target into protein, carbohydrate, and fat grams using your chosen macro ratio.
How much protein do I need per day?
For general health, 0.8 g per kg of body weight is the minimum. For muscle building or fat loss while preserving muscle, 1.6–2.2 g per kg is recommended by sports nutrition research. The calculator's Standard split allocates 30% of calories to protein. For a 2,000 kcal diet that equals 150 g of protein per day. If you are very active or focused on muscle gain, the High Protein preset (40% protein) is more appropriate.
What is the difference between BMR and TDEE?
BMR (Basal Metabolic Rate) is the number of calories your body needs at complete rest to maintain basic life functions — breathing, circulation, and cell repair. TDEE (Total Daily Energy Expenditure) is your BMR multiplied by an activity factor, representing the total calories you actually burn in a day including exercise and daily movement. To lose fat, eat below your TDEE. To gain muscle, eat above it. Your macro targets are then calculated from this calorie goal.
What is the best macro split for weight loss?
For weight loss, higher protein intake helps preserve muscle while in a calorie deficit. The Standard (30/40/30) or High Protein (40/35/25) presets work well for most people. If you prefer a low-carbohydrate approach, the Keto preset (30/10/60) can be effective. The most important factor is maintaining a sustained calorie deficit — usually 250–500 kcal below your TDEE — while consistently hitting your protein target.
What macro split is best for building muscle?
For muscle gain (bulking), a calorie surplus of 250–500 kcal above TDEE combined with adequate protein is key. The High Protein preset (40/35/25) or High Carb Athletic preset (25/55/20) are popular choices. Carbohydrates fuel intense training sessions and support recovery, so athletes often benefit from higher carb intakes. Protein should be at least 1.6 g per kg of body weight to maximise muscle protein synthesis.
What is the Katch-McArdle formula and when should I use it?
The Katch-McArdle formula calculates BMR based on lean body mass (total weight minus fat mass) rather than total weight. It is more accurate for people who know their body fat percentage — particularly leaner individuals or athletes — because it correctly accounts for the fact that muscle burns more calories at rest than fat does. To use it, enter your body fat percentage in Advanced Mode. If you do not know your body fat, Mifflin-St Jeor is the recommended default.
How much water should I drink per day?
A common guideline is approximately 35 ml of water per kg of body weight per day, with additional amounts for physical activity. The Advanced Mode adds 300–1,200 ml depending on your activity level. For example, a 70 kg moderately active person would need roughly 3,050 ml (about 3 litres) per day. These are estimates — thirst, climate, and sweat rate all affect individual needs.

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