Health & Fitness

Macro Calculator

Calculate your optimal daily calories and precise grams of protein, carbohydrates, and fats for fat loss, muscle building, or healthy weight maintenance.

Biological Gender Mifflin-St Jeor formula adjusts for baseline metabolic variance

Age

years

Valid range: 15 to 100 years

Current Weight

lbs

Enter your morning body weight before eating

Height

Enter feet and remaining inches

Height

Enter height in centimeters

Physical Activity Level Be conservative: most people who work desk jobs and train 3 days fall into Lightly to Moderately Active

Fitness & Weight Goal Adjusts daily caloric intake relative to your maintenance burn

Macronutrient Split Profile High-protein splits maximize muscle preservation during cuts

Daily Meal Frequency (for per-meal target breakdown) Divides your daily targets evenly to guide portion sizing

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Enter your age, weight, and height above, or click "Try an example" to view instant macro targets.

Standard Fat Loss (-500 kcal)

Target Daily Caloric Intake

2,334

Calories / Day (kcal)

Eat this amount to lose approximately 1.0 lb (~0.45 kg) of body fat per week

Protein

233 g

933 kcal

40% of calories

Carbohydrates

204 g

817 kcal

35% of calories

Dietary Fats

65 g

583 kcal

25% of calories

Macronutrient Energy Share 40% Protein • 35% Carbs • 25% Fat

Protein (4 kcal/g)

Carbohydrates (4 kcal/g)

Dietary Fats (9 kcal/g)

Maintenance Baseline (TDEE)

2,834 kcal

Calories to maintain current weight

Basal Metabolic Rate (BMR)

1,828 kcal

Resting metabolic calorie floor

Weekly Net Caloric Deficit

-3,500 kcal

Expected fat loss: -1.0 lb / week

Protein Intake Density

1.23 g / lb

grams per pound of bodyweight

Daily Nutrition & Per-Meal Portions (4 meals/day)

Macronutrient	Daily Target	Daily Calories	Per Meal Target
Protein (4 kcal/g)	233 g	933 kcal	58.3 g / meal
Carbohydrates (4 kcal/g)	204 g	817 kcal	51.0 g / meal
Dietary Fats (9 kcal/g)	65 g	583 kcal	16.3 g / meal
Total Energy Intake	502 g	2,334 kcal	583 kcal / meal

How to Use This Calculator

Follow these four simple steps to calculate your custom daily macronutrient targets:

Choose Your Unit System: Select either US Customary (pounds, feet, inches) or Metric (kilograms, centimeters) using the toggle at the top of the card.
Enter Your Personal Metrics: Enter your biological gender, age, morning body weight, and height. These baseline metrics determine your Basal Metabolic Rate (BMR).
Select Your Activity Level & Goal: Choose your weekly exercise frequency and your target fitness goal—whether you want to cut body fat, maintain current weight, or build lean muscle mass.
Pick Your Macronutrient Split: Choose a diet profile (Balanced, High-Protein Athletic, Low-Carb, or Keto) and set your preferred daily meal frequency to review your itemized per-meal portion guide.

The Formula

GrabCalc utilizes the clinically validated Mifflin-St Jeor equation—widely recognized by the American Dietetic Association as the most accurate clinical BMR formula—combined with standardized macronutrient energy densities:

Step 1: Basal Metabolic Rate (Mifflin-St Jeor) Men: BMR = 10 × Weight (kg) + 6.25 × Height (cm) − 5 × Age + 5 Women: BMR = 10 × Weight (kg) + 6.25 × Height (cm) − 5 × Age − 161 Step 2: Total Daily Energy Expenditure (TDEE) TDEE = BMR × Physical Activity Factor • Sedentary (1.20) • Lightly Active (1.375) • Moderately Active (1.55) • Very Active (1.725) Step 3: Target Caloric Intake Target Calories = TDEE + Goal Calorie Delta • Standard Fat Loss: −500 kcal/day (∼1 lb/week fat loss) • Lean Muscle Bulk: +250 to +500 kcal/day Step 4: Macronutrient Gram Conversions Protein Grams = (Target Calories × Protein %) ÷ 4 kcal/g Carb Grams = (Target Calories × Carb %) ÷ 4 kcal/g Fat Grams = (Target Calories × Fat %) ÷ 9 kcal/g

Understanding the Energy Densities

Protein (4 calories per gram): Required for repairing skeletal muscle fibers, synthesizing hormones, and maintaining high satiety while in a caloric deficit.
Carbohydrates (4 calories per gram): The body's primary and most efficient fuel source for high-intensity muscular contractions, brain cognition, and central nervous system stamina.
Dietary Fats (9 calories per gram): Dense energy carriers essential for testosterone production, thyroid regulation, joint lubrication, and the absorption of fat-soluble vitamins (A, D, E, K).

Example

Let us walk through a complete, realistic scenario for a 30-year-old male who wants to lose body fat while lifting weights:

Scenario: 30-Year-Old Male Cutting Body Fat

Weight: 190 lbs (86.18 kg)
Height: 5 ft 10 in (70 inches = 177.8 cm)
Activity Level: Moderately Active (lifts weights 4 days/week = 1.55x)
Goal: Standard Fat Loss (−500 kcal/day = ~1.0 lb loss per week)
Diet Style: High Protein Athletic (40% Protein / 35% Carbs / 25% Fat)

Step-by-Step Calculation:

Compute BMR:
$ ext{BMR} = (10 imes 86.18) + (6.25 imes 177.8) - (5 imes 30) + 5 = 861.8 + 1,111.25 - 150 + 5 = \mathbf{1,828 ext{ kcal/day}}$.
Compute TDEE:
$ ext{TDEE} = 1,828 imes 1.55 = \mathbf{2,834 ext{ kcal/day}}$ (maintenance level).
Apply Caloric Deficit:
$ ext{Target Calories} = 2,834 - 500 = \mathbf{2,334 ext{ kcal/day}}$.
Determine Macronutrient Grams:
- Protein (40%): $(2,334 imes 0.40) \div 4 = 933.6 \div 4 = \mathbf{233 ext{ grams}}$ ($1.23 ext{ g/lb}$ bodyweight).
- Carbohydrates (35%): $(2,334 imes 0.35) \div 4 = 816.9 \div 4 = \mathbf{204 ext{ grams}}$.
- Dietary Fat (25%): $(2,334 imes 0.25) \div 9 = 583.5 \div 9 = \mathbf{65 ext{ grams}}$.

Across 4 daily meals, this lifter aims for approximately 58g of protein, 51g of carbs, and 16g of fat per meal to achieve predictable fat loss without muscle wasting.

Frequently Asked Questions

What are macros and why are they important?

Macros (macronutrients) are the three primary dietary sources of energy: Protein (4 calories per gram), Carbohydrates (4 calories per gram), and Dietary Fats (9 calories per gram). Tracking macros ensures you preserve lean muscle mass during fat loss and optimize hormonal balance, rather than simply restricting total calories blindly.

How does this macro calculator determine my daily calories?

The calculator first determines your Basal Metabolic Rate (BMR) using the clinically validated Mifflin-St Jeor formula based on your gender, age, height, and weight. It multiplies BMR by your physical activity factor to find your Total Daily Energy Expenditure (TDEE), then adjusts for your specific weight goal (deficit for fat loss, surplus for muscle growth).

Which macro split profile should I choose?

For general wellness and sustainable weight management, the Balanced profile (40% carbs, 30% protein, 30% fat) works best for most people. For lifters, athletes, and intense cutting phases, High Protein (35% carbs, 40% protein, 25% fat) maximizes muscle retention and satiety. Low-Carb and Ketogenic profiles suit those managing insulin sensitivity or endurance protocols.

Should I weigh my food raw or cooked?

Weighing food in its raw state is always the most accurate practice. Cooking evaporates water from meats (making cooked meat calorie-denser per gram) and adds water to rice and pasta (making cooked grains lighter in calories per gram). Standard nutritional food labels reflect raw, unprepared ingredients.

Is my health or personal data private on GrabCalc?

Yes, 100%. All calculations execute entirely inside your local device browser via client-side JavaScript. Your age, weight, body measurements, and dietary goals are never stored, logged, or transmitted across any server.