Macro Calculator
Get your daily calories and protein, carb, and fat targets based on your body, activity level, and goal. Uses the Mifflin–St Jeor equation.
| Macro | % of calories | Grams/day |
|---|---|---|
| Protein | 30% | 202 g |
| Carbs | 40% | 269 g |
| Fat | 30% | 90 g |
Uses the Mifflin–St Jeor equation and a balanced 30/40/30 split. Estimates only — individual needs vary. Not medical advice.
How to use this calculator
Enter your biological sex, age, height (feet and inches), and weight (pounds). Choose your typical activity level and your goal — fat loss, maintenance, or lean gain. The calculator returns your daily calorie target and the corresponding grams of protein, carbohydrates, and fat.
Why macros matter beyond calories
Total calories determine whether you gain, lose, or maintain weight over time. But the composition of those calories — how much protein, carbohydrate, and fat you eat — shapes what you gain or lose. Adequate protein during a calorie deficit helps preserve lean muscle, which keeps your metabolism from slowing as sharply. Sufficient carbohydrates fuel high-intensity training so performance does not suffer. Fat supports hormone production and absorption of fat-soluble vitamins (A, D, E, K). Getting all three in reasonable proportions is what macro tracking is designed to ensure.
How the calculation works, step by step
The calculator follows this sequence:
- Step 1 — BMR: Your resting calorie burn is estimated with the Mifflin–St Jeor equation (10×kg + 6.25×cm − 5×age ± constant).
- Step 2 — TDEE: BMR is multiplied by an activity factor (1.2 to 1.9) to account for movement and exercise.
- Step 3 — Goal adjustment: For fat loss, calories are set approximately 20% below TDEE. For maintenance, TDEE is the target. For lean gain, calories are set approximately 15% above TDEE.
- Step 4 — Macro split: Adjusted calories are allocated 30% to protein, 40% to carbohydrates, and 30% to fat.
- Step 5 — Grams: Protein and carbohydrate grams are calculated at 4 calories per gram; fat grams at 9 calories per gram.
Worked example — step by step
A 30-year-old man, 5 feet 10 inches, 170 lb, moderately active, goal: fat loss.
- BMR: 10 × 77.1 + 6.25 × 177.8 − 5 × 30 + 5 ≈ 1,815 calories
- TDEE (×1.55): 1,815 × 1.55 ≈ 2,810 calories
- Fat-loss target (−20%): 2,810 × 0.80 ≈ 2,250 calories
- Protein (30%): 2,250 × 0.30 ÷ 4 ≈ 169 g
- Carbohydrates (40%): 2,250 × 0.40 ÷ 4 ≈ 225 g
- Fat (30%): 2,250 × 0.30 ÷ 9 ≈ 75 g
Verification: (169 × 4) + (225 × 4) + (75 × 9) = 676 + 900 + 675 = 2,251 calories ✓
How to interpret your results
Your macro targets are starting points, not immovable rules. Aim to hit your protein target first — it is the most important for body composition during both deficit and surplus phases. Carbohydrates and fat can flex based on preference and how your energy and hunger respond. Track your average intake over a week rather than stressing over each individual day.
If your weight is not moving in the expected direction after 2–3 weeks, adjust total calories by 100–200 kcal and reassess. Recalculate your macros any time your weight changes by 10 lb or more.
Common mistakes to avoid
- Neglecting protein on a deficit. Cutting calories without adequate protein is the fastest way to lose muscle alongside fat. Protein is the highest priority macro during fat loss.
- Quitting after one bad day. Missing your macros one day does not undo progress. Weekly averages matter far more than daily perfection.
- Not adjusting as you lose weight. As your body mass decreases, your TDEE decreases too. Recalculate every 10 lb to keep your targets accurate.
- Confusing net carbs with total carbs. This calculator uses total carbohydrates (including fiber). If you follow a low-carb approach, check how your tracking app handles fiber.
- Overestimating activity level. Choosing "very active" when "moderately active" fits better inflates your calorie target significantly and can stall fat loss.
The formulas
BMR (men): 10×kg + 6.25×cm − 5×age + 5
BMR (women): 10×kg + 6.25×cm − 5×age − 161
TDEE = BMR × activity factor · Adjusted calories = TDEE × goal multiplier
Protein(g) = calories × 0.30 ÷ 4 · Carbs(g) = calories × 0.40 ÷ 4 · Fat(g) = calories × 0.30 ÷ 9
Estimates for general informational purposes, not medical or dietary advice. Consult a registered dietitian or physician for personalized guidance.
How we calculate this
BMR is estimated with the Mifflin–St Jeor equation, multiplied by an activity factor (1.2–1.9) to get TDEE, then adjusted for goal (≈−20% for fat loss, +15% for lean gain). Calories are split 30% protein, 40% carbohydrate, 30% fat; grams are derived from caloric density (4 kcal/g protein and carbs, 9 kcal/g fat). Results are estimates; not medical or dietary advice.
Sources
Frequently asked questions
What are macros?
Macros — macronutrients — are the three nutrients that provide calories: protein, carbohydrates, and fat. Protein and carbohydrates each supply about 4 calories per gram; fat supplies about 9 calories per gram. Tracking the grams of each gives you much more control over body composition than counting calories alone.
How are my macros calculated?
The calculator estimates your BMR using the Mifflin–St Jeor equation, multiplies by your activity factor to get your maintenance calories (TDEE), then adjusts for your goal (roughly −20% for fat loss, +15% for lean gain). Those adjusted calories are split into grams using a 30% protein, 40% carbohydrate, and 30% fat ratio.
How much protein do I really need?
The calculator allocates 30% of calories to protein, which works out to roughly 0.7–0.9 g per lb of body weight for most people — a solid general target. Those cutting calories aggressively or training at high volume often benefit from the higher end of 0.7–1 g per lb to protect muscle mass during a deficit.
Can I adjust the macro ratios?
The default split (30/40/30) is a balanced starting point for general fitness. People following a lower-carb approach might shift carbs down and fat up while keeping protein the same. The total calorie target matters most; macro ratios are a secondary tool for managing energy, hunger, and training performance.
Should I eat the same macros every day?
Aiming for consistency is useful, especially early on, because it makes tracking simpler and lets you observe cause and effect. Over time, some people cycle macros — eating more carbs on training days and fewer on rest days. Either approach can work; pick the one you can sustain. Average intake over the week matters more than any single day.
What is the difference between macros and calories?
Calories measure total energy; macros tell you where that energy is coming from. 2,000 calories of mostly protein and vegetables affects satiety, muscle retention, and body composition very differently from 2,000 calories of refined carbohydrates and fat, even though the calorie total is identical.
How long does it take to see results from hitting my macros?
Meaningful body composition changes typically take 4–8 weeks to become visible, and scale weight may fluctuate for the first few weeks due to changes in water retention, food volume, and glycogen stores. Track trends over at least 3–4 weeks before deciding whether to adjust your targets.
Do macros differ by age or sex?
The ratio recommendations used here are broad population guidelines. Individual protein needs may be slightly higher for older adults (over 50) to help offset age-related muscle loss. Women generally have lower absolute calorie and macro targets than men of the same size due to differences in lean mass, but the ratio principles remain the same.