Macro Calculator
Enter your daily calorie target and select a diet goal to get your recommended protein, carbohydrate, and fat targets in grams and calories.
How Macro Calculator works
What are macronutrients?
Macronutrients are the three main categories of nutrients that provide energy: protein (4 kcal per gram), carbohydrates (4 kcal per gram), and fat (9 kcal per gram). Unlike micronutrients (vitamins and minerals), which are needed in small amounts, macronutrients are consumed in large quantities to fuel the body. The ratio of protein, carbs, and fat in the diet significantly affects body composition, energy levels, and health outcomes.
Protein targets
Protein is essential for muscle repair and growth, immune function, and satiety. The UK Reference Nutrient Intake (RNI) is 0.75g per kg of body weight per day for sedentary adults, but athletes, people losing weight, and older adults typically benefit from higher intakes of 1.2–2.2g per kg. Higher protein diets tend to preserve muscle during calorie restriction and improve satiety, making them popular for fat loss.
Carbohydrates and energy
Carbohydrates are the body's primary fuel source, particularly for the brain and during high-intensity exercise. The NHS recommends that carbohydrates make up about a third of the diet. Low-carbohydrate diets (20–100g/day) can be effective for weight loss and blood sugar control, particularly for people with type 2 diabetes. Ketogenic diets restrict carbs to below 50g/day, shifting the body to burn fat as its primary fuel.
Dietary fat
Fat is essential for hormone production, cell membrane health, and absorption of fat-soluble vitamins (A, D, E, K). Not all fats are equal: unsaturated fats (olive oil, nuts, fish) are beneficial; trans fats (partially hydrogenated oils) are harmful; saturated fats (butter, meat) should be moderated. Dietary fat does not directly cause body fat accumulation — overall calorie balance determines weight change.
Frequently asked questions
How much protein do I need per day?
The UK RNI is 0.75g per kg of body weight. For muscle building, most research supports 1.6–2.2g per kg of body weight. For weight loss, higher protein (1.6–2.4g/kg) helps preserve muscle mass. As a rough guide, 25–40% of calories from protein covers most people's needs.
What is a ketogenic diet?
A ketogenic (keto) diet restricts carbohydrates to around 5% of calories (typically under 50g/day), with 70% or more from fat and 25% from protein. When carbohydrate stores are depleted, the liver produces ketones from fat as an alternative fuel. Ketosis can aid fat loss and has therapeutic applications for epilepsy and some metabolic conditions.
Should I track my macros?
Macro tracking is useful for people with specific body composition goals (muscle gain, fat loss) or dietary requirements (managing blood sugar, athletic performance). For most people seeking general health improvement, focusing on food quality — vegetables, lean protein, healthy fats, whole grains — without precise tracking achieves good results.
What's the best macro split for weight loss?
There is no universally "best" split. Higher protein (35–40%) helps preserve muscle and increases satiety during a calorie deficit. Lower carbohydrate approaches may help some people manage hunger and blood sugar. The key factor for weight loss is the overall calorie deficit, not the specific macro ratio.
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This calculator provides estimates for informational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider.