About the Macro Calculator
This macro calculator works out how many grams of protein, carbohydrate and fat to eat each day. It first estimates your maintenance calories (Mifflin-St Jeor BMR × activity), adjusts them for your goal — losing fat, maintaining or building muscle — and then divides those calories using the macro split you choose.
Pick a ready-made split such as balanced 30/40/30, high protein, low carb, the US Acceptable Macronutrient Distribution Ranges, low fat or keto, or enter your own percentages. The result shows daily grams, calories from each macro and per-meal targets, so you can plug the numbers straight into a tracking app or meal plan.
Macros are converted using 4 kcal per gram for protein and carbohydrate and 9 kcal per gram for fat. The calculator also shows your protein in grams per kilogram of body weight — for most active people 1.6–2.2 g/kg is a useful target, so check that line before settling on a split.
With the default inputs, the daily calories is 2,263 kcal. Change any value above to recalculate instantly.
How to use the macro calculator
- 1Enter your sex, age, height, weight and activity level.
- 2Choose a goal: fat loss, maintenance or muscle gain.
- 3Pick a macro split, or choose Custom and enter your own percentages.
- 4Set how many meals you eat per day.
- 5Use the grams per day (and per meal) as targets in your food tracker.
Formula and method
Maintenance calories come from the Mifflin-St Jeor BMR equation multiplied by an activity factor (1.2 to 1.9). The goal adds or subtracts a fixed amount: 250–500 kcal below maintenance for fat loss, or 250–500 kcal above for muscle gain.
The calorie target is then divided by the chosen percentages. Protein and carbohydrate provide about 4 kcal per gram and fat about 9 kcal per gram (Atwater factors), so each macro’s calories are divided by its energy density to get grams. Custom percentages that do not total 100% are scaled proportionally.
- P%, C%, F%
- Share of calories from protein, carbohydrate and fat
- 4, 4, 9
- kcal per gram of protein, carbohydrate and fat
Worked examples
30-year-old man, 5 ft 10 in, 180 lb, moderately active, fat loss, balanced split
His BMR is about 1,783 kcal and maintenance about 2,763 kcal. Subtracting 500 kcal gives 2,263 kcal. A 30/40/30 split gives 2,263 × 0.30 ÷ 4 ≈ 170 g protein, 2,263 × 0.40 ÷ 4 ≈ 226 g carbs and 2,263 × 0.30 ÷ 9 ≈ 75 g fat — about 57 g protein per meal over 3 meals.
35-year-old woman, 165 cm, 62 kg, lightly active, maintaining on a high-protein split
BMR = 10 × 62 + 6.25 × 165 − 5 × 35 − 161 ≈ 1,315 kcal, so maintenance is about 1,808 kcal. At 40/30/30 that is about 181 g protein, 136 g carbs and 60 g fat per day.
Custom 25/45/30 split on a lean bulk
Adding 250 kcal to 2,763 kcal maintenance gives about 3,013 kcal. At 25% protein, 45% carbs and 30% fat that is roughly 188 g protein, 339 g carbs and 100 g fat per day.
Frequently asked questions
What are macros?+
Macronutrients are the three nutrients that supply calories: protein (about 4 kcal per gram), carbohydrate (about 4 kcal/g) and fat (about 9 kcal/g). Alcohol also provides about 7 kcal/g but is not counted as a macro target.
What is the best macro split for weight loss?+
Total calories matter most for weight loss, but a higher protein intake — around 1.6–2.2 g per kg of body weight — helps preserve muscle and control hunger. Carbs and fat can then be split to suit your preferences and training.
What macro ratio do the dietary guidelines recommend?+
US Acceptable Macronutrient Distribution Ranges for adults are 10–35% of calories from protein, 45–65% from carbohydrate and 20–35% from fat. The “AMDR” option uses 20/50/30, which sits inside all three ranges.
Do I need to hit my macros exactly?+
No. Being within about 5–10 g of your protein target and roughly on your calorie target most days is enough. Carbs and fat can flex against each other as long as calories stay similar.
How do I count macros?+
Log what you eat in a food-tracking app or read nutrition labels, weigh foods where possible, and compare daily totals to your targets. Many people start by tracking only calories and protein, then add carbs and fat later.
This tool gives general estimates and is not medical advice. Talk to a doctor or qualified professional about your health, diet or training.