BodyCalWhat this macro calculator does
This calculator turns your body stats and goal into a concrete daily eating plan: how many calories to eat, and exactly how to split them across protein, carbohydrate, and fat in grams. Instead of guessing, you get targets you can track in any food app, plus a visual breakdown so you can see your plate at a glance.
It's built for whatever you're chasing — losing fat, maintaining, or building muscle — and lets you choose a diet style (balanced, lower-carb, or higher-protein) to match how you like to eat.
How your numbers are calculated
The calculator works in three steps:
- Maintenance calories (TDEE): estimated from your age, sex, height, weight, and activity using the Mifflin–St Jeor equation — the formula recommended by the Academy of Nutrition and Dietetics.
- Goal adjustment: about a 20% calorie deficit for fat loss, maintenance calories to stay the same, or a roughly 15% surplus to support muscle gain.
- Macro split: your target calories are divided into protein, carbs, and fat using your chosen diet style, then converted to grams (protein and carbs at 4 kcal/g, fat at 9 kcal/g).
Why protein comes first
Of the three macros, protein is the one most worth getting right. It preserves muscle while you're in a calorie deficit, has the strongest effect on fullness, and costs the most energy to digest. Research supports around 1.6–2.2 g per kilogram of body weight per day for people who train or are losing weight. The high-protein and balanced presets here aim for that range.
Carbs and fat: fuel and function
Carbohydrates are your body's preferred fuel for hard training and brain function; cutting them too low can sap energy and workout quality. Dietary fat supports hormones and the absorption of vitamins A, D, E, and K, so going extremely low-fat is also a mistake. The right balance between them is largely personal preference — pick the split you can sustain.
How to use your targets
Log your food in any tracker and aim to land within about 5–10 grams of each target most days, prioritising your protein goal first. Re-run the numbers every few weeks or after a noticeable weight change, since your calorie needs shift as your body does. Pair this with our calorie deficit calculator to plan your timeline, and the body fat calculatorto confirm you're losing fat rather than muscle. New to all this? Start with our beginner's guide to counting macros for weight loss.