Calculate macronutrient breakdown.
Enter calories and ensure sum = 100%.
Guide to Macronutrients
Importance of macronutrients
Macronutrients are the three main nutrients providing energy: protein, carbohydrates, and fat. Each plays a unique role in the body. Protein is essential for building and repairing tissues, carbohydrates provide energy for activity and brain function, and fat supports vitamin absorption and hormone production. Proper macronutrient distribution is key to achieving training goals.
Recommended ratios
- Protein - 25-40% of calories (1.6-2.2 g/kg for athletes)
- Carbohydrates - 40-55% of calories (5-8 g/kg for active)
- Fat - 20-30% of calories (0.6-1 g/kg)
Meal planning
Distribute your macronutrients across 4-5 meals throughout the day, starting with breakfast. Each meal should contain protein sources (poultry, fish, eggs, legumes), complex carbohydrates (grains, rice, vegetables), and healthy fats (olive oil, nuts, avocado). Increase carbohydrates before training, focus on protein with moderate carbs after training.
Individualization
Ideal ratios depend on goal, body type, and training intensity. People losing weight may benefit from more protein (40%) at the expense of carbohydrates. Endurance athletes need more carbohydrates (60%+). Experiment and observe how your body responds for 2-3 weeks, then adjust ratios based on results.
A 30% protein target means 1.69 g/kg or 2.81 g/kg depending only on how much you eat
Macros expressed as percentages of calories float with your intake. For an 80 kg person, the same 30% protein rule gives 135 g at 1,800 kcal and 225 g at 3,000 — 1.69 g/kg against 2.81 g/kg. Protein requirement tracks body mass, not calorie intake, so a percentage rule moves the target every time you change how much you eat.
How it works
- Splits a calorie target into protein, carbohydrate and fat in grams.
- Accepts protein as g/kg of body weight as well as a percentage, since the two answer different questions.
- Converts between grams and calories at 4, 4 and 9 kcal per gram.
protein 4 kcal/g · carbohydrate 4 kcal/g · fat 9 kcal/g set protein from body mass: grams = weight (kg) × target g/kg set fat as a share of calories, then carbohydrate takes the remainder carb kcal = total − protein kcal − fat kcal
Worked example
An 80 kg person at a protein target of 1.8 g/kg, across different calorie levels.
- 1.8 g/kg × 80 kg = 144 g protein = 576 kcal, at every calorie level
- a 30% rule at 1,800 kcal gives 135 g → 1.69 g/kg
- the same rule at 2,200 kcal gives 165 g → 2.06 g/kg
- at 2,600 kcal gives 195 g → 2.44 g/kg
- at 3,000 kcal gives 225 g → 2.81 g/kg
One percentage rule produces a 66% range in the figure that actually matters. Anchoring protein to body mass keeps it fixed at 144 g whether you are eating 1,800 or 3,000, which is the behaviour you want when calories change and your body does not.
Reading the result
- Fat carries 2.25 times the energy of protein or carbohydrate per gram, so a percentage of calories is a much smaller share of the food. At 2,400 kcal, fat at 30% of calories is 80 g — only 16.0% of the total grams on the plate.
- The order that works is protein first from body mass, fat next as a share of calories, carbohydrate last as whatever remains. Carbohydrate is the flexible term because it is the one with no separate minimum requirement in the way the other two have.
- Commonly used protein ranges run from roughly 1.2 g/kg for general health up to around 2.2 g/kg when training hard in a calorie deficit. These are population guidelines rather than individual prescriptions, and higher is not automatically better.
- Anyone with kidney disease, diabetes, an eating-disorder history, or who is pregnant should set macro targets with a clinician rather than a calculator. The arithmetic here is sound and says nothing about whether a given split is appropriate for you.
Common questions
- Should I set protein as a percentage or per kilogram?
- Per kilogram. Your protein requirement is a function of body mass and training, not of how many calories you happen to be eating. A percentage rule silently raises the target when you eat more and lowers it when you eat less, which is backwards during a deficit.
- Why does a low-fat plan look like so much food?
- Because fat is 9 kcal per gram against 4 for the others. Shifting calories out of fat and into carbohydrate more than doubles the grams they occupy — at 2,400 kcal, moving fat from 40% to 20% of calories adds 120 g of carbohydrate to the plate.