Macro Calculator — Free Macros for Bulking, Cutting & Maintenance with AI
This macro calculator uses the Mifflin-St Jeor formula and research-backed protein, fat, and carb ratios — trusted by nutrition coaches and reviewed against peer-reviewed sports nutrition guidelines — to build a personalized daily target.
Your details
All fields are required. Height and weight are entered in metric units.
What is a Macro Calculator?
A macro calculator is a tool that converts your daily calorie target into specific gram amounts of protein, carbohydrates, and fat based on your body stats, activity level, and goal. Instead of just telling you "eat 2,200 calories," it tells you how to split those calories — for example, 180g protein, 220g carbs, and 60g fat — so you can plan meals that support muscle retention, energy levels, and your weight goal at the same time.
Below is a quick reference for how protein, carbs, and fat typically shift depending on your goal and diet style. Protein is shown in grams per kilogram of bodyweight (g/kg), fat as a percentage of total calories, and carbs fill whatever calories remain.
| Goal | Diet style | Protein (g/kg) | Fat (% of calories) | Carbs |
|---|---|---|---|---|
| Cut | Balanced / High-protein | 2.2 g/kg | 25% | Remainder |
| Cut | Low-carb | 2.0 g/kg | 35% | Remainder (lower) |
| Maintain | All styles | 1.8 g/kg | 25-35% | Remainder |
| Bulk | Balanced / Low-carb | 1.8 g/kg | 25-35% | Remainder (higher) |
| Bulk | High-protein | 2.0 g/kg | 25% | Remainder |
| Any | High-protein adjustment | +0.2 g/kg | 25% | Remainder (lower) |
How the Macro Calculator Works — The Formula
This calculator runs three calculations in sequence: it estimates your basal metabolic rate (BMR), scales that by your activity level to get total daily energy expenditure (TDEE), then adjusts for your goal and splits the resulting calories into protein, carb, and fat targets.
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 × activity multiplier
Step 3 — Goal adjustment
Cut: TDEE − 500 kcal/day (roughly 0.45 kg / 1 lb of fat loss per week). Bulk: TDEE + 400 kcal/day, a moderate surplus that supports muscle gain without excessive fat gain. Maintain: calories stay equal to TDEE. The calculator never lets the final target fall below 1,200 kcal/day for women or 1,500 kcal/day for men — if your inputs would drop below that floor, the target is clamped and a warning explains why.
Step 4 — Macro split
Protein is set first as grams per kilogram of bodyweight, based on your goal and diet preference (see the table above). Fat is set as a percentage of total calories — 25% for balanced and high-protein diets, 35% for low-carb. Carbs receive whatever calories remain after protein and fat are accounted for:
Carb calories = Total calories − (Protein g × 4) − (Fat g × 9)
Carb grams = Carb calories ÷ 4
- BMR
- Basal metabolic rate — calories burned at complete rest.
- TDEE
- Total daily energy expenditure — your maintenance calories, including activity.
- g/kg
- Grams of a nutrient per kilogram of your bodyweight.
- kcal
- Kilocalories — the energy unit used for food labels and daily targets.
- Deficit/Surplus
- The difference between your calorie target and your TDEE.
Worked example
A 30-year-old man, 75 kg, 175 cm, moderately active, choosing to cut on a balanced diet:
- BMR = 10 × 75 + 6.25 × 175 − 5 × 30 + 5 = 750 + 1,093.75 − 150 + 5 = 1,698.75 kcal
- TDEE = 1,698.75 × 1.55 ≈ 2,633 kcal
- Cut target = 2,633 − 500 ≈ 2,133 kcal
- Protein = 2.2 g/kg × 75 kg = 165g (660 kcal)
- Fat = 25% of 2,133 kcal ≈ 533 kcal ÷ 9 ≈ 59g
- Carbs = (2,133 − 660 − 533) ÷ 4 ≈ 235g
Cutting calories too aggressively — going far below your BMR — can backfire. A deficit larger than about 500-750 kcal/day often leads to muscle loss, fatigue, and a slowed metabolism, and is harder to sustain. Pairing a steep deficit with low protein makes muscle loss even more likely. Stick to a moderate deficit and keep protein at or above about 1.6-2.2 g/kg.
How to Use the Macro Calculator
- Select your Sex (Male or Female) — this determines which BMR formula is used.
- Enter your Age, Height (cm), and Weight (kg).
- Choose your Activity level — be honest, since this is the most common source of error in calorie estimates.
- Pick your Goal (Cut, Maintain, or Bulk) and your Diet preference (Balanced, Low-carb, or High-protein).
- Click Calculate to see your results instantly.
- Scroll to the AI Insights section to understand what your result means.
How to Interpret Your Macro Calculator Results
What a Good Result Looks Like
A solid macro plan has protein in the 1.6-2.2 g/kg range, which research consistently links to muscle retention and satiety for active individuals — our cutting targets default to the top of that range. Your calorie target should also represent a sustainable change of about 300-500 kcal/day above or below maintenance, not a drastic swing. If your numbers fall in these ranges, the plan is reasonable to start with.
Warning Signs in Your Results
Be cautious if your daily calorie target sits below roughly 1,200 kcal for women or 1,500 kcal for men — sustained intake below these floors is difficult to maintain and can affect energy, hormones, and training performance, which is why this calculator clamps the target and flags it. On a "low-carb" selection, if carbs fall below about 26% of total calories without you intending a strict ketogenic approach, the plan may feel unnecessarily restrictive. And if protein drops below about 1.2 g/kg while cutting, you're at higher risk of losing muscle along with fat.
How to Improve Your Result
If your numbers don't match how you feel in practice, start by re-checking your activity level — most people overestimate it, which inflates the calorie target. If your deficit or surplus feels too aggressive, choose a smaller adjustment (closer to 250-300 kcal/day) for a slower but more sustainable change. If protein feels too low, switch your diet preference to "High-protein" to add roughly 0.2 g/kg. Finally, recalculate every 4-6 weeks as your bodyweight changes — your TDEE shifts along with it, so a target that worked at a higher weight will gradually need adjusting.
Macro Calculator Examples
Bulking Macro Split for a 75kg Lifter
A 25-year-old male lifter wants to add muscle while limiting fat gain.
- 75 kg, 178 cm, moderately active, Goal: Bulk, Diet: Balanced
Result: roughly 3,000 kcal/day with about 135g protein, 85g fat, and 380g carbs. What this means: the extra carbs fuel heavier training sessions and recovery, while protein at 1.8 g/kg protects against excess fat gain relative to muscle gain. What to do next: track weekly bodyweight — gaining more than about 0.5 kg/week suggests the surplus is too large.
Cutting Macros on a Low-Carb Diet
A 35-year-old woman wants to lose fat without feeling constantly hungry, and prefers fewer carbs.
- 65 kg, 165 cm, lightly active, Goal: Cut, Diet: Low-carb
Result: roughly 1,500 kcal/day with about 130g protein, 58g fat, and 110g carbs. What this means: the higher fat percentage (35%) and elevated protein (2.0 g/kg) help with satiety during a deficit, while carbs are reduced but not eliminated. What to do next: if 110g of carbs feels too low for training energy, consider switching to "Balanced" to free up more carbs at the same calorie level.
Maintenance Macros for a Moderately Active Adult
A 40-year-old man wants to hold his current weight while improving body composition slightly.
- 85 kg, 180 cm, moderately active, Goal: Maintain, Diet: Balanced
Result: roughly 2,800 kcal/day with about 153g protein, 78g fat, and 350g carbs. What this means: calories match TDEE, so weight should stay roughly stable while protein at 1.8 g/kg supports muscle maintenance. What to do next: if body composition goals shift toward fat loss or muscle gain later, switch the Goal field to Cut or Bulk and recalculate.
This calculator provides an estimate only and is not medical or nutrition advice. It uses standard formulas and general guidelines that may not reflect your individual metabolism, medical history, medications, or activity patterns. Calorie and macro needs vary significantly between individuals, and the AI Insights are generated from your inputs, not a clinical assessment. If you have a medical condition, are pregnant or breastfeeding, are managing an eating disorder, or are unsure how to apply these numbers, consult a registered dietitian or doctor before making changes to your diet.
Frequently Asked Questions about the Macro Calculator
What are macros and why do they matter?
Macros (macronutrients) are the three nutrient groups that supply calories: protein, carbohydrates, and fat. Each has a different role — protein builds and repairs muscle, carbs fuel activity and brain function, and fat supports hormones and nutrient absorption. Hitting calorie and macro targets together gives you more control over body composition than counting calories alone, because two diets with the same calories can produce very different results depending on the protein-to-fat-to-carb split.
How does this macro calculator determine my targets?
It first estimates your basal metabolic rate (BMR) using the Mifflin-St Jeor equation from your sex, age, height, and weight. That BMR is multiplied by your activity level to get your TDEE (maintenance calories). Your goal (cut, maintain, or bulk) adjusts that calorie number, then protein is set per kilogram of bodyweight based on your goal and diet preference, fat is set as a percentage of total calories, and carbs fill the remaining calories.
How do protein, carb, and fat ratios change for cutting vs. bulking?
On a cut, protein is set higher (around 2.0-2.4 g/kg) to protect muscle while in a calorie deficit, and calories run about 500 below maintenance. On a bulk, protein sits closer to 1.8-2.0 g/kg and calories run about 400 above maintenance, leaving more room for carbs to fuel training and recovery. Maintenance uses a moderate 1.8 g/kg protein target with calories at TDEE.
How accurate is the TDEE estimate behind these macros?
The Mifflin-St Jeor formula is generally accurate to within about 10% for most people, but the activity multiplier you choose is the biggest source of error. Many people overestimate how active they are, which inflates the calorie target. Treat the result as a starting point: track your actual intake and bodyweight for 2-3 weeks and adjust from there.
How often should I recalculate my macros?
Recalculate every 4-6 weeks, or sooner if your bodyweight changes by more than about 2-3 kg, your activity level changes significantly, or you switch goals (e.g. from cutting to maintenance). Your TDEE shifts as your bodyweight changes, so a target that worked at 80 kg may need adjusting once you reach 75 kg.
What is the difference between low-carb, balanced, and high-protein diets here?
Balanced sets fat at 25% of calories and protein at standard levels, leaving a moderate carb allowance. Low-carb raises fat to 35% of calories and slightly lowers the protein-per-kg target on a cut, which reduces carbs significantly — useful if you find high-carb eating leaves you hungrier. High-protein keeps fat at 25% but adds roughly 0.2 g/kg more protein than the balanced setting, trimming carbs slightly in exchange for more protein, which can help with satiety and muscle retention.
What if I'm not seeing results after following my macros?
First confirm you are actually hitting your targets consistently — most "not working" cases are tracking errors, not metabolic ones. If intake is accurate and weight has not moved in 2-3 weeks, adjust calories by about 100-200 kcal/day in the direction of your goal (down for a stalled cut, up for a stalled bulk) and re-check after another 2-3 weeks. Also re-verify your activity level is realistic.
Does this macro calculator replace advice from a dietitian or doctor?
No. This tool provides a mathematical estimate based on standard formulas and general guidelines — it does not account for medical conditions, medications, eating disorders, pregnancy, or individual metabolic differences. If you have a health condition, are pregnant or breastfeeding, or have a history of disordered eating, talk to a registered dietitian or doctor before adopting a new calorie or macro target.