Macro Calculator

Macros is short for macronutrients — the three energy-providing nutrients your body needs in large amounts: protein (4 kcal/g), carbohydrate (4 kcal/g), and fat (9 kcal/g). The ratio in which you eat them affects body composition, athletic performance, satiety, and hormonal health. "Counting macros" means hitting specific gram targets for each one each day rather than just tracking total calories. Protein adequacy and total calorie balance matter most — the exact carbs-to-fat split is more flexible.

This macro calculator uses a three-step process: (1) Calculate BMR using the Mifflin-St Jeor equation (10w + 6.25h − 5a + sex constant). (2) Multiply BMR by your activity factor (1.2 sedentary → 1.9 extra active) to get TDEE. (3) Add or subtract calories for your goal (cut −500, bulk +500), then split the total into protein, carbs, and fat by your chosen percentages. Divide each percentage by the calories per gram (4 for protein and carbs, 9 for fat) to get gram targets.

For fat loss, prioritise high protein (1.6-2.2 g per kg of body weight, or about 30-40% of calories) to preserve muscle in a deficit. Set fat at 0.5-0.8 g/kg (20-30% of calories) for hormonal health, and fill the rest with carbs. A typical cutting split is 35% protein / 35% carbs / 30% fat. The exact carbs-to-fat ratio is personal preference — adherence matters far more than the ratio. Stick to whole foods, lean protein, vegetables, and fruit, and you'll succeed at any split.

For muscle gain you need a calorie surplus (+250-500 kcal/day) and enough protein (1.6-2.0 g/kg) plus high-quality training. A common bulk split is 25% protein / 50% carbs / 25% fat. The higher carb percentage fuels hard training and supports recovery; the moderate fat keeps testosterone production healthy. Protein above 2.2 g/kg gives no extra muscle-building benefit and just displaces carbs and fat from your calorie target — so don't go overboard.

Evidence-based ranges by goal: Sedentary adults 0.8 g/kg minimum (RDA). Active adults & strength trainers 1.6-2.2 g/kg (roughly 0.7-1.0 g/lb). Cutting / fat loss 1.8-2.5 g/kg — higher protein protects muscle during a calorie deficit and increases satiety. Older adults preserving muscle 1.2-1.6 g/kg. Going above 2.5 g/kg has no proven extra benefit for most people and just displaces other macros from your calorie budget. Spread protein over 3-5 meals of 20-50 g each for best muscle-protein synthesis.

A standard ketogenic split is approximately 70-75% fat, 20-25% protein, 5-10% carbs — usually under 50 g of net carbs per day, and sometimes under 20 g. This carb restriction shifts your body into ketosis, where it burns fat (via ketone bodies) for fuel instead of glucose. Keto works for some people — it controls appetite well and may help with insulin sensitivity — but it is not magical; total calorie balance still determines fat loss. Keto can be hard to sustain, restrictive socially, and may underperform for high-intensity athletes whose performance depends on stored glycogen.

Not necessarily. Total calories matter most for body composition. But hitting a protein target (1.6-2.2 g/kg) makes any calorie target much more effective: more muscle preservation in a cut, more lean gain in a bulk, more satiety overall. Many people get great results from tracking protein only and eating intuitively from the remaining calorie budget. Counting all three macros is most useful for athletes, competitors, and anyone whose previous calorie-only approach has stalled.

No, carbs are not bad. The "carbs are evil" narrative was a marketing story from the low-carb diet boom of the 2000s — not science. Carbs are the body's preferred energy source for high-intensity exercise and brain function. What actually matters is total calorie balance, protein adequacy, and food quality. Whole-food carbs (vegetables, fruit, oats, rice, potatoes, beans) support performance, satiety, and gut health. Ultra-processed carbs and sugary drinks are best limited — but moderate intake of any carb in a calorie-controlled diet won't sabotage results.

Aim for at least 0.5-0.8 g of fat per kg of body weight per day (typically 20-35% of total calories). Fat is essential for hormone production (especially testosterone and oestrogen), absorption of vitamins A, D, E, and K, brain function, and joint health. Going below 0.4 g/kg long-term can disrupt hormonal balance and recovery. Most people do well in the 25-35% range; ketogenic dieters push it to 70%+, while extreme cuts may briefly drop to 15-20%. Prioritise unsaturated fats (olive oil, nuts, fish, avocado) over saturated and trans fats.

The Mifflin-St Jeor BMR equation is accurate within ±10% for most healthy adults, and the macro ratios are evidence-based starting points used by registered dietitians and sports nutritionists worldwide. Real-world accuracy depends on three things: how honestly you log food, how consistently you train, and how your individual metabolism responds. Treat the calculator's output as a starting point. After 2-3 weeks at the target, adjust calories by 100-150 kcal/day if the scale isn't moving in the right direction.

For most people: yes — a flat daily split is simplest and works well. Some advanced lifters benefit from carb cycling: higher carbs on training days, lower carbs on rest days, with a weekly average that matches their target. The evidence for an advantage over a flat split is mixed, but carb cycling can help with appetite control and may improve performance on key training sessions. Start with a flat split — only experiment with cycling once you have several months of consistent tracking behind you.

Use a free nutrition tracking app like MyFitnessPal, Cronometer, or MacroFactor. Weigh whole foods on a digital kitchen scale for the most accurate logs — measuring cups are notoriously imprecise for things like rice, oats, peanut butter, and oils. Aim to be within ±5 g of each macro target most days; occasional misses are fine. Most people find that 10 days of careful logging teaches them roughly what their meals contain, after which they can eyeball portions and only formally log when changing diet or scaling up.