Macro calculator: protein, carbs and fat for your goal
Turn your calorie target into grams of protein, carbs and fat. Three goals, three splits and a fat floor, with the full math and a worked example.
How do I calculate my macros?
Start with a calorie target, then set protein first, fat second, and give carbs the rest. Protein is usually 1.6–2.4 g per kg of body weight depending on your goal. Fat is 25–40% of calories but not under about 0.6 g/kg. Protein and carbs carry 4 kcal per gram and fat 9, so divide each share of calories by those numbers to get grams.
How to use the calculator
- Enter your body and activityFill in sex, age, height and weight, then your activity level. Together they set your maintenance calories.
- Pick a goalLose fat takes 20% off maintenance, Maintain keeps it, and Build muscle adds 10%. The goal also sets your protein.
- Pick a splitChoose Balanced, Higher protein or Lower carb. Each one changes the share of calories from fat and how much protein you get.
- Read your gramsYou get a daily calorie target and grams of protein, carbs and fat, each with its share of calories. The colored bar shows the split at a glance.
Macros are the three nutrients that carry calories: protein, carbohydrate and fat. Calories decide whether your weight moves. Macros shape what that weight is made of and how you feel while it moves. Protein protects muscle. Carbs fuel hard training. Fat carries fat-soluble vitamins and supports hormone production. The longer explainer is what macros are.
The formula
The calculator works in four steps, in this order.
- Calories: TDEE (Mifflin-St Jeor BMR × activity factor) × goal adjustment, rounded to the nearest 10 kcal
- Protein (g): body weight (kg) × protein per kg for your goal and split
- Fat (g): calories × fat share ÷ 9, but never under 0.6 × body weight (kg)
- Carbs (g): (calories − protein × 4 − fat × 9) ÷ 4
| Goal | Calories | Balanced (30% fat) | Higher protein (25% fat) | Lower carb (40% fat) |
|---|---|---|---|---|
| Lose fat | −20% | 2.0 g/kg | 2.4 g/kg | 2.2 g/kg |
| Maintain | Maintenance | 1.6 g/kg | 2.0 g/kg | 1.8 g/kg |
| Build muscle | +10% | 1.8 g/kg | 2.2 g/kg | 2.0 g/kg |
The cells are protein per kg of body weight. Protein is highest when you are cutting, because a deficit is when muscle is most at risk. It sits in between for building muscle, where the extra calories already help. The Higher protein split adds 0.4 g/kg to any goal and the Lower carb split adds 0.2 g/kg.
A worked example
Take the default person: a woman of 30, 168 cm and 68 kg, exercising 3–5 days a week. Her maintenance is 1,419 × 1.55 = 2,199 kcal. She chooses Lose fat and Balanced. Her calories are 2,199 × 0.8 = 1,759, rounded to 1,760 kcal.
- Protein: 68 × 2.0 = 136 g, or 544 kcal (31%)
- Fat: 1,760 × 0.30 ÷ 9 = 59 g, or 528 kcal (30%)
- Carbs: (1,760 − 544 − 528) ÷ 4 = 172 g (39%)
Switch the goal to Maintain and she gets 2,200 kcal: 109 g protein, 276 g carbs and 73 g fat. Build muscle gives 2,420 kcal: 122 g protein, 301 g carbs and 81 g fat.
The fat floor
Fat is set as a share of calories, and that share can run thin when calories are low and body weight is high. So the calculator never lets fat drop under 0.6 g per kg. Take a 40-year-old man, 180 cm and 100 kg, sedentary, choosing Lose fat and Higher protein. His target is 1,850 kcal. A 25% fat share would be 51 g, but the floor lifts fat to 58 g. Protein is 233 g and carbs get the remaining 98 g.
The BMI cap
Per-kg rules scale with total weight, fat included, and the research behind them was done on fairly lean people. So for protein and the fat floor, the calculator uses your weight capped at the weight that gives a BMI of 30 for your height. For the man above that is 97 kg instead of 100, which barely moves anything. For a woman of 45, 160 cm and 120 kg, sedentary, choosing Lose fat, the cap is 77 kg. Her target is 1,740 kcal: 154 g protein, 58 g fat and 151 g carbs. Without the cap, protein would be 240 g and carbs would shrink to 33 g. Many dietitians make the same move by basing protein on a goal weight.
How accurate is it?
The grams are only as good as the calorie target above them, and that target is an estimate. Mifflin-St Jeor misses for some people, and activity levels are coarse. The protein numbers stand on firmer ground. They follow the research on training and dieting, which the protein calculator covers source by source. The split between carbs and fat matters least. Trials that hold calories and protein equal find similar fat loss on lower-carb and lower-fat diets, so pick the split you can keep eating.
What to do with your macros
Treat the grams as a daily budget, not a test. Hit protein most days, stay near the calorie target, and let carbs and fat float. Then log what you eat. A macro tracker shows where the day stands, and an AI calorie counter that reads a plate photo makes the logging quicker. FORM sets its own calorie targets with the same Mifflin-St Jeor equation × an activity factor. For muscle goals it sets protein at 2.0 g/kg, puts fat at about 25% of energy and gives carbs the rest. Every target is editable.
FAQ
What are good macros for weight loss?
Keep protein high, around 1.8–2.4 g per kg of body weight, and keep fat above a sensible floor. How you split the rest between carbs and fat matters less than landing near your calorie target.
Do I need to hit my macros exactly?
No. Hitting protein and landing near your calorie target most days does most of the work. Weekly averages matter more than any single day.
Should I pick the lower-carb split?
Pick it if you like eating that way. With calories and protein equal, lower-carb and higher-carb diets give similar fat loss in studies. If you train hard most days, more carbs often feel better.
Why is my protein target so high?
Training and dieting both call for well over the RDA, so it is set per kg of body weight. The weight it uses is capped at a BMI of 30 for your height, so the number does not run away if you carry a lot of body fat.
How many calories are in a gram of protein, carbs and fat?
Protein and carbohydrate have about 4 kcal per gram, fat about 9. Alcohol has about 7, so drinks add calories that don’t show up as protein, carbs or fat.