Quick Answer
Enter your age, sex, weight, height, activity level and goal in the calculator below to get your exact daily grams of protein, carbs and fats.
The tool uses the Mifflin-St Jeor equation for your calorie baseline and then dials in protein by bodyweight (0.8 to 2.2 g/kg) before splitting the remaining calories.
This avoids the trap of generic 40/30/30 percentage splits, which under-feed light bodies and over-feed heavy ones.
What is a macro split?
A macro split is the daily ratio of protein, carbohydrates and fats that makes up your total calories. Protein and carbs each provide 4 kcal per gram, fats provide 9.
Hitting the right split is what separates "weight loss" from "fat loss". Calories drive the scale, but macros drive your body composition.
The protein-first method
Most calculators use percentages, which scale poorly across body sizes. I use a three-step protein-first method instead.
- Step 1: Set protein from bodyweight (0.8 to 2.2 g/kg, scaled to activity).
- Step 2: Subtract protein calories from your daily total.
- Step 3: Split the remaining calories between carbs and fats based on your carb-timing preference.
Macro Split Calculator
Protein-first split tailored to your goal and carb timing.
Get a personalised gram split of protein, carbs, and fats for fat loss, maintenance, or muscle gain.
Activity levels and protein dosing
Protein needs scale with physical demand. Use this table to see how the calculator dials in your gram target.
| Activity Level | Protein Factor | Who is this for |
|---|---|---|
| Sedentary | 0.8 g/kg | Office job, little to no exercise (RDA minimum) |
| Lightly Active | 1.2 g/kg | Light exercise or sport 1 to 3 days a week |
| Moderate | 1.6 g/kg | Moderate training 3 to 5 days a week (general fitness) |
| Very Active | 2.0 g/kg | Hard exercise 6 to 7 days a week |
| Extra Active | 2.2 g/kg | Physical job plus hard training (athlete max) |
Carb timing options
Once protein is locked in, the remaining calories are split between carbs and fats based on your training style.
| Option | Carbs | Fats | Best for |
|---|---|---|---|
| Standard | 50% | 50% | Balanced, flexible everyday eating |
| Low Carb | 25% | 75% | Sedentary days, fat-adaptation phases |
| High Carb | 60% | 40% | Endurance and hypertrophy training |
Why track macros at all?
- Satiety: hitting protein targets reduces hunger and cravings.
- Body composition: ensures the weight you lose is fat, not muscle.
- Performance: adequate carbs fuel high-intensity workouts and recovery.
- Hormonal health: dietary fat supports testosterone, estrogen and vitamin absorption.
Calculation methodology
BMR is calculated with the Mifflin-St Jeor equation, the gold standard for resting energy.
- Men: 10 × W + 6.25 × H − 5 × A + 5
- Women: 10 × W + 6.25 × H − 5 × A − 161
TDEE is BMR multiplied by your activity factor (1.2 to 1.9). Goal calories adjust TDEE by −500 kcal for fat loss or +300 kcal for muscle gain. Protein grams are weight × your protein factor. Remaining calories are then split between carbs and fats by your chosen ratio.
Frequently asked questions
How accurate is this macro calculator?
It uses Mifflin-St Jeor for BMR and evidence-based protein dosing of 0.8 to 2.2 g/kg. That is significantly more accurate than fixed percentage calculators because it respects body size first.
What is the 4-4-9 rule?
It is the calorie value of each macro per gram. Protein and carbs both supply 4 kcal per gram, fats supply 9. The calculator uses this to convert your gram targets back into total daily calories.
Why protein first instead of percentage splits?
A 50 kg person needs far less protein than a 100 kg athlete. Setting protein by bodyweight ensures realistic minimums for muscle and health, then the rest of the calories are split between carbs and fats.
Is a 40/30/30 split good for fat loss?
The Zone Diet split (40% carbs, 30% protein, 30% fat) is a solid starting point. The protein-first method usually lands close to it for moderate trainers, but adjusts upward for heavier or very active people.
Is 30% fat too high?
No. 30% fat is healthy and sustainable. Fat is essential for hormone production and vitamin absorption. Going below 20% for long stretches can hurt mood, hormones and skin.
What is the best macro split for fat loss?
One you can stick to. Physiologically, higher protein wins for fat loss because it preserves muscle and increases satiety. The Standard or Low Carb timing usually works best in a deficit.
Is this a good macro calculator for bodybuilding?
Yes. Pick Very Active or Extra Active to push protein to 2.0 to 2.2 g/kg, and pair it with High Carb timing to maximise glycogen replenishment for heavy lifting.
Does it work for women?
Yes. The BMR equation accounts for sex, and I recommend keeping fats around the Standard split to support hormonal health.
What if I get a "calories too low" error?
Your protein target exceeded your remaining calorie budget. Increase your activity level or switch from fat loss to maintenance to give the calculation more headroom.
How often should I recalculate macros?
Every 4 to 6 weeks, or whenever your weight shifts by 3 to 5 kg. As you lose weight, your BMR drops and your targets need a refresh.
Should I worry more about calories or macros?
Calories drive weight, macros drive composition. If you only care about the scale, calories matter most. If you care about looking toned and keeping muscle, hitting your protein number matters just as much.
Is my data safe?
Yes. The calculation runs entirely in your browser. Nothing is stored or sent to a server.
Related calculators
- Calorie Calculator, set the daily total your macros split out of.
- BMR and TDEE, see your resting and total daily burn.
- Body Fat Calculator, fine-tune protein targets using lean mass.
- BMI Calculator, quick weight-status screen against WHO standards.
Medical disclaimer
This calculator and article are for general educational and wellness purposes only. They are not a substitute for professional medical advice, diagnosis or treatment. Results are estimates based on population formulas and do not account for every individual factor.
If you are pregnant or breastfeeding, under 18, over 65, an athlete, recovering from illness or surgery, or living with a chronic condition (diabetes, heart, kidney, thyroid, eating disorder), speak to a qualified healthcare professional before changing your diet, exercise or hydration habits based on these numbers.
See the full site-wide Disclaimer & Notice for the complete terms that apply to every calculator and tool on dmbio.
