Macro Calculator
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What Your Result Means
- Daily Calories: Your estimated total daily energy expenditure (TDEE) adjusted for your goal. For weight loss, 500 calories are subtracted (roughly 1 lb/week loss); for gain, 500 are added. Maintenance holds TDEE steady.
- Protein: Grams per day at 4 kcal/g. Higher protein during a cut (35%) helps preserve lean mass. During maintenance or gain, 30% provides sufficient amino acids for recovery and growth.
- Carbs: Grams per day at 4 kcal/g. Carbs fuel high-intensity exercise and replenish glycogen stores. The gain preset allocates 50% to support heavy training loads.
- Fat: Grams per day at 9 kcal/g. Fat supports hormone production, cell membranes, and absorption of fat-soluble vitamins. Even 20–25% of total calories provides adequate dietary fat for most adults.
How This Calculator Works
You enter age, sex, height, weight, activity level, and goal. The tool estimates BMR using the Mifflin-St Jeor equation — the most validated simple BMR formula — then multiplies by an activity factor to get TDEE. A ±500 kcal adjustment is applied for fat loss or gain. Calories are split into protein, carbs, and fat using goal-specific ratios and converted to grams (4 kcal/g for protein and carbs, 9 kcal/g for fat). It does not account for body fat percentage, metabolic adaptation, or medical conditions.
Quick Questions
How accurate is Mifflin-St Jeor?
Studies show it predicts BMR within about 10% for most healthy adults, making it the most accurate simple formula available. However, it can underestimate needs for very muscular individuals and overestimate for those with high body fat percentage.
Is a 500-calorie deficit safe?
A 500 kcal/day deficit targets roughly 1 pound of weight loss per week, which is generally considered safe and sustainable for most adults. Larger deficits may lead to muscle loss, fatigue, and nutrient deficiencies. Consult a healthcare provider for personalized guidance.
What activity level should I choose?
Most people overestimate their activity level. If you exercise 3–4 days per week for 30–60 minutes, "moderately active" is typically appropriate. Desk workers who exercise 1–2 days per week should generally select "lightly active."
Should I track macros or just calories?
For general weight management, tracking total calories is usually sufficient. Macro tracking adds value if you're trying to optimize body composition (preserve muscle while losing fat), fuel athletic performance, or follow a specific dietary protocol.
How does this differ from the Macro Split calculator?
The Macro Split calculator takes a calorie number you already know and divides it into macros. This calculator estimates your calorie needs from scratch using your stats and activity level, then splits them into macros — it is the more comprehensive starting point.
Sources
- Mifflin et al. (1990) — A new predictive equation for resting energy expenditure (Mifflin-St Jeor BMR formula)
- USDA Dietary Guidelines for Americans (calorie and macronutrient guidance)
- Jäger et al. (2017) — ISSN Position Stand on Protein and Exercise (protein recommendations for active individuals)
Method & review
Estimate only. Results reflect your inputs and standard formulas — they are not financial, tax, legal, health, or investment advice. Verify important decisions with a qualified professional.