Estimate your daily calorie target from your stats and activity level, then see it split into protein, fat, and carb targets based on whether you're cutting, maintaining, or building.
Your BMR (calories burned at rest) is estimated with the Mifflin-St Jeor formula, multiplied by an activity factor to get your daily maintenance calories (TDEE), then adjusted for your goal and split into protein, fat, and carbs.
"Macros" is short for macronutrients — the three sources of dietary energy: protein, fat, and carbohydrates. While total calories determine whether you gain, lose, or maintain weight, the macro split determines the quality of that outcome: enough protein to preserve muscle during a deficit or build it during a surplus, enough fat for hormone health, and carbs to fuel training and daily activity. Two people eating the same total calories but very different macro splits can see meaningfully different results in body composition, energy levels, and training performance.
Where W is weight in kg, H is height in cm, and A is age in years. This is the widely-used Mifflin-St Jeor equation, generally considered more accurate than older formulas like Harris-Benedict for most adults.
Activity multipliers range from 1.2 (sedentary, little or no exercise) to 1.9 (extra active, athletes training daily) — this scales your resting burn up to reflect how much you actually move in a typical day.
| Goal | Adjustment |
|---|---|
| Lose weight | TDEE − 500 kcal/day (roughly 0.5 kg/week loss) |
| Maintain | TDEE (no adjustment) |
| Gain weight | TDEE + 300 kcal/day (lean, gradual gain) |
This calculator uses a balanced 30% protein / 30% fat / 40% carbs split by default — a reasonable general-purpose starting point. Protein and carbs each provide 4 kcal per gram; fat provides 9 kcal per gram.
Example — Moderate activity, maintaining: A 30-year-old, 75 kg, 175 cm male with moderate activity has a BMR of about 1,724 kcal, a TDEE of about 2,672 kcal, and — since the goal is maintenance — a target of roughly 2,672 kcal split into about 200 g protein, 89 g fat, and 267 g carbs.
Example — Cutting: The same profile aiming to lose weight targets 2,172 kcal/day (TDEE minus 500), with macros scaling down proportionally to about 163 g protein, 72 g fat, and 217 g carbs.
Example — Lower activity female: A 28-year-old, 62 kg, 165 cm female with light activity has a BMR of about 1,317 kcal and a TDEE of about 1,811 kcal at maintenance.
Which BMR formula does this calculator use? The Mifflin-St Jeor equation, which is widely regarded as more accurate for most adults than older formulas like Harris-Benedict.
Why does my calorie target change with my activity level? Because TDEE (total daily energy expenditure) scales your resting metabolic rate up based on how active you are — a more active lifestyle burns more calories on top of BMR.
How much of a deficit is safe for weight loss? A deficit of around 500 kcal/day is a common, moderate target that typically produces roughly 0.5 kg (about 1 lb) of loss per week without being overly aggressive.
Why is the macro split 30/30/40 by default? It's a balanced, general-purpose starting point suitable for most goals — athletes or specific diet approaches (like higher-protein or lower-carb) may prefer a different split.
Should I eat exactly this many calories every single day? Treat it as a weekly average target rather than a strict daily rule — day-to-day variation is normal and expected.
How often should I recalculate my macros? Recalculate whenever your weight changes by roughly 5–10 lbs (2–5 kg), or if your activity level changes significantly.
Does this account for muscle mass or body fat percentage? No — this uses a standard formula based on weight, height, age, and sex only; body composition tools like a body fat calculator can refine this further.
Why is protein important even at maintenance calories? Adequate protein supports muscle repair and maintenance regardless of whether you're losing, maintaining, or gaining weight.
What if my real-world results don't match this estimate? BMR formulas carry a typical margin of error of 10–15% — track your actual results for 2–3 weeks and adjust calories by 100–200 kcal if needed.