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Fill in your details and tap Calculate My Macros to see your personalised daily calorie target and protein, carbohydrate, and fat breakdown.
The following table shows the macro splits used by this online macronutrient calculator for each goal preset, alongside the resulting calorie adjustment from your TDEE.
| Goal | Calorie Adjustment | Protein | Carbohydrates | Fat | Best For |
|---|---|---|---|---|---|
| Lose Fast | −20% (aggressive deficit) | 40% | 30% | 30% | Jump-start weight loss |
| Lose Weight | −15% (moderate deficit) | 35% | 35% | 30% | Steady fat loss, muscle retention |
| Maintain | ±0% (TDEE) | 30% | 40% | 30% | Body recomposition, health |
| Lean Muscle Gain | +10% (lean surplus) | 30% | 45% | 25% | Muscle growth with minimal fat |
| Bulk / Fast Gain | +20% (aggressive surplus) | 25% | 50% | 25% | Mass gain, off-season athletes |
| Keto | ±0% to −10% | 25% | 5% | 70% | Ketosis, low-carb fat loss |
* Protein minimum is always set to at least 0.7g per lb bodyweight (1.55g/kg) to protect lean mass.
An online macronutrient calculator converts your personal stats — age, sex, height, weight, and activity level — into daily gram targets for the three macronutrients: protein, carbohydrates, and fat. It works in two stages: first it estimates your Total Daily Energy Expenditure (TDEE), then it splits those calories across the macros based on your chosen goal. Think of it as a precision nutrition macro calculator — one that replaces generic advice with numbers specific to your body.
Unlike a simple calorie counter, a macro calculator tells you where those calories should come from, which matters because protein, carbs, and fat each serve distinct biological roles — muscle repair, energy supply, and hormone production respectively. Getting the ratios right is what separates goal-driven eating from guesswork.
Your Basal Metabolic Rate (BMR) is the number of calories your body burns at complete rest — breathing, cell maintenance, organ function. Your Total Daily Energy Expenditure (TDEE) multiplies BMR by an activity factor (1.2 to 1.9) to account for movement, training, and daily tasks. TDEE is your maintenance calorie level: eat at it to hold weight, below it to lose fat, above it to build muscle.
This calculator uses the Mifflin-St Jeor equation by default — the most validated formula for the general population. If you enter your body fat percentage, it automatically switches to the more precise Katch-McArdle formula, which calculates BMR from lean body mass directly. Athletes and experienced lifters typically get better results with Katch-McArdle.
Protein is the most important macronutrient for body composition regardless of your goal. It builds and repairs muscle tissue, provides satiety, and has the highest thermic effect of food — your body burns roughly 20–30% of protein calories just to digest it. The precision nutrition macro calculator approach recommends a protein baseline of at least 0.7–1.0g per pound of bodyweight (1.55–2.2g/kg) for active adults.
During a calorie deficit, going higher — up to 1.2g/lb — actively protects lean muscle from being broken down for fuel. For muscle building, research supports 0.8–1.0g/lb. At 4 calories per gram, a 150g protein target equals 600 kcal and is typically the anchor around which carbs and fat are then distributed.
Carbohydrates are your body's preferred energy source, particularly for the brain and during moderate-to-high-intensity exercise. At 4 calories per gram, they fill the gap between your protein target and total calorie goal. For most active individuals on a maintenance or muscle-building protocol, carbs represent 40–50% of total calories — fuelling training and glycogen replenishment.
For fat loss goals, carbs are typically pulled back to 30–40% to create the calorie deficit while keeping dietary fat and protein stable. Net carbs (total carbs minus fiber) are particularly relevant for keto diet calculator users, where the target is often below 25–50g net carbs per day to maintain nutritional ketosis.
The ketogenic diet shifts your primary fuel source from glucose to ketone bodies — molecules produced by the liver from fat when carbohydrate intake is severely restricted. A standard keto diet calculator targets roughly 70% fat, 25% protein, and 5% carbohydrates. Achieving and maintaining ketosis requires keeping net carbs below 25–50g per day for most individuals, though this threshold varies by person.
Fat becomes the dominant macro at 9 calories per gram. On a 2,000 kcal keto plan that means roughly 155g of fat daily — from sources like avocados, olive oil, nuts, cheese, and fatty fish. Protein must be adequate but not excessive, as surplus protein can be converted to glucose through gluconeogenesis, potentially disrupting ketosis. Our keto diet calculator preset sets these ratios automatically and enforces the protein floor.
Fat at 9 kcal/gram is the most calorie-dense macronutrient. It is essential for absorbing fat-soluble vitamins (A, D, E, K), producing sex hormones, protecting organs, and maintaining cell membrane integrity. A precision nutrition approach recommends fat at no less than 20% of total calories to avoid hormonal disruption, particularly in women.
The type of fat matters as much as the quantity. Unsaturated fats from olive oil, avocados, salmon, and nuts support heart health and reduce inflammation. Saturated fats should be kept moderate. Trans fats should be eliminated entirely. This online macronutrient calculator focuses on quantity; for fat quality guidance, see our nutrition articles.