Macro Calculator
Calculate your TDEE and optimal macronutrient targets using the Mifflin-St Jeor equation. Get personalized protein, carb, and fat goals for fat loss, maintenance, or muscle building.
Your results
BMR
1,741
TDEE
2,699
Target calories
2,699cal
Maintenance — no adjustment
Protein
202g
Protein per lb
0.80 g/lb
Carbs
270g
Fat
90g
What Are Macronutrients?
Macronutrients — protein, carbohydrates, and fat — are the three categories of nutrients that supply all the calories in your diet. Each serves a distinct physiological role and contains a set number of calories per gram:
- Protein (4 cal/g) — builds and repairs muscle tissue, supports immune function, and produces enzymes and hormones. Higher protein intake is especially important during fat loss to preserve lean mass.
- Carbohydrates (4 cal/g) — your body's preferred fuel source for high-intensity exercise and brain function. Stored as glycogen in muscles and liver.
- Fat (9 cal/g) — essential for hormone production (including testosterone), vitamin absorption, and cell membrane integrity. Provides sustained energy at lower intensities.
Tracking macros rather than just total calories gives you more control over body composition outcomes — two diets with the same calories but different macro ratios can produce very different results in muscle retention and performance.
TDEE Explained
Your Total Daily Energy Expenditure (TDEE) is the total number of calories you burn in a 24-hour period. It has four components:
- Basal Metabolic Rate (BMR) — calories burned at complete rest to keep you alive. This accounts for 60-75% of total expenditure.
- Thermic Effect of Food (TEF) — energy spent digesting food, roughly 10% of intake. Protein has the highest thermic effect at 20-30%.
- Exercise Activity Thermogenesis (EAT) — calories burned through intentional exercise.
- Non-Exercise Activity Thermogenesis (NEAT) — energy from all other movement: walking, fidgeting, standing, household tasks.
The activity multipliers used in this calculator (1.2 to 1.9) are estimates that account for TEF, EAT, and NEAT combined. Your actual TDEE may differ by 10-15% — treat the result as a starting point and adjust based on real-world weight trends over 2-3 weeks.
The Mifflin-St Jeor Formula
This calculator uses the Mifflin-St Jeor equation (1990) to estimate BMR. It is considered the gold standard among predictive metabolic equations and is recommended by the Academy of Nutrition and Dietetics.
Men: BMR = (10 × weightkg) + (6.25 × heightcm) − (5 × age) + 5
Women: BMR = (10 × weightkg) + (6.25 × heightcm) − (5 × age) − 161
The equation takes weight in kilograms and height in centimeters. If you enter imperial units, this calculator converts automatically before applying the formula. Your TDEE is then calculated as BMR multiplied by your activity factor.
How to Count Macros
Once you have your targets, tracking macros is straightforward:
- Step 1: Weigh your food using a kitchen scale. Volume measurements (cups, tablespoons) are less accurate, especially for calorie-dense foods like nuts and oils.
- Step 2: Log everything in a tracking app or spreadsheet. Focus on hitting your protein target first — it's the most important macro for body composition.
- Step 3: Fill remaining calories with carbs and fat according to your split. Some flexibility between carbs and fat is fine as long as neither goes extremely low.
- Step 4: Monitor your weight weekly (same time, same conditions). Adjust calories by 100-200 if weight trend doesn't match your goal after 2-3 weeks.
Frequently Asked Questions
What are macronutrients?
Macronutrients are the three main categories of nutrients your body needs in large amounts: protein (4 calories per gram), carbohydrates (4 calories per gram), and fat (9 calories per gram). Together they make up all the calories you consume.
How accurate is the Mifflin-St Jeor equation?
The Mifflin-St Jeor equation is considered the most accurate predictive BMR equation for most adults, with studies showing it predicts resting metabolic rate within 10% for about 80% of people. It was developed in 1990 and is recommended by the Academy of Nutrition and Dietetics.
How much protein do I need per day?
Research supports 0.7-1.0 grams of protein per pound of body weight for active individuals. For fat loss, higher protein (1g/lb) helps preserve muscle mass. For maintenance, 0.8g/lb is sufficient. For muscle building, 1g/lb is a well-supported target.
Should I eat below my TDEE to lose weight?
Yes. A deficit of 300-500 calories below your TDEE is a sustainable rate for fat loss, translating to roughly 0.5-1 pound per week. Larger deficits risk muscle loss, metabolic adaptation, and are harder to maintain long-term.
Do I need to hit my macros exactly every day?
No. Hitting your targets within 5-10 grams on protein and staying close on total calories matters most. Carb and fat ratios are more flexible. Consistency over weeks matters far more than perfection on any single day.