About the Macro Calculator
This macro calculator turns your stats into a concrete daily eating target. It first estimates the calories you burn using the Mifflin-St Jeor equation — the formula dietitians consider the most reliable for resting metabolism — scaled by your activity level, then shifts that number down for fat loss or up for muscle gain depending on your goal. The result is a calorie target you can actually plan meals around.
Calories alone don't tell you what to put on the plate, so the calculator splits your target into grams of protein, carbohydrate and fat across three ready-made patterns: a balanced split, a low-carb split and a high-protein split favored for preserving muscle while dieting. Pick the style that matches how you like to eat, and you'll have exact gram targets to plug into any food-tracking app tonight.
Features
- Calories from the Mifflin-St Jeor equation plus activity
- Goal modes for losing, maintaining or gaining weight
- Protein, carb and fat targets in exact grams
- Balanced, low-carb and high-protein diet splits
- Metric and imperial height and weight inputs
- Free, instant and private — no account needed
How to calculate your macros
- Enter your age, sex, height and weight.
- Choose the activity level that matches a typical week.
- Pick your goal: lose fat, maintain or build muscle.
- Read your daily calorie target.
- Choose a diet style to get protein, carb and fat grams.
Frequently asked questions
How are my calories and macros calculated?
Resting calories come from Mifflin-St Jeor: 10×weight(kg) + 6.25×height(cm) − 5×age, plus 5 for men or minus 161 for women. That's multiplied by an activity factor of roughly 1.2–1.9, then adjusted for your goal. Macros divide the final calories by each split's ratios, at 4 kcal per gram of protein or carbs and 9 per gram of fat.
How much protein do I actually need?
For active people, research generally supports around 1.6–2.2 g of protein per kilogram of body weight daily — well above the sedentary minimum. Higher intakes help preserve muscle in a calorie deficit, which is why the high-protein split is popular for dieting. The calculator's gram targets land in this evidence-backed zone.
What's the difference between the diet splits?
The balanced split spreads calories conventionally across all three macros and suits most people. Low-carb trims carbohydrates in favor of fat, which some find better for appetite control. High-protein pushes protein up at the expense of carbs and fat, prioritizing muscle retention and satiety during weight loss.
How fast will I lose or gain weight on these numbers?
The goal adjustment creates a moderate surplus or deficit — typically in the range that produces about 0.25–0.5 kg of change per week, a pace that's sustainable and protects muscle. Real-world results vary, so weigh yourself weekly and nudge calories up or down if progress stalls for several weeks.
Is this medical or dietetic advice?
No. These are estimates from population equations — your true metabolism can differ by a couple of hundred calories either way, and conditions like diabetes, thyroid disorders or a history of disordered eating change what's appropriate. Treat the numbers as a starting point and consult a professional for personal guidance.