Macro Calculator

This calculator works out your daily calorie target from your size, activity level and goal, then splits it into protein, fat and carbohydrate. Change the split and the calories stay the same; only the balance between the three moves.

What macronutrients are

In health and fitness, macronutrients are the compounds we eat in large quantities that supply energy: carbohydrate, protein and fat. Some definitions stretch to water, calcium, sodium and chloride, on the grounds that the body needs them in bulk. This calculator covers the three that carry calories.

Micronutrients are the other half of nutrition: vitamins and dietary minerals such as vitamin A, copper, iron and iodine. Macronutrients are needed in grams per day. Micronutrients are usually needed in under 100 milligrams.

Only four things in the diet supply energy, and the arithmetic behind every macro split comes from these numbers:

Nutrient	Calories per gram
Fat	9
Alcohol	7
Protein	4
Carbohydrate	4

Fat carries more than twice the energy of protein or carbohydrate per gram, which is why a fat-heavy split always produces a smaller-looking number of grams for the same calories.

Protein

Proteins are organic compounds built from amino acids. Nine of those amino acids cannot be made by the body and have to come from food, which is why they are called essential. Protein in the diet is where they come from.

Sources are both animal, including meat and dairy, and plant, including beans, legumes, nuts and seeds. Supplements exist and are useful for convenience rather than for anything they do that food cannot. As with most things, moderation matters, and some protein sources are better than others.

Healthier choices include soy, beans, nuts, fish, skinless poultry, lean beef, pork and low-fat dairy. Less healthy ones include fried meats, processed meats such as deli slices, sausages and fast-food burgers, high-sugar yogurts, processed protein bars and many cheeses.

The RDA is 0.8 grams per kilogram of body weight a day, which is the floor for avoiding deficiency rather than a target for anyone training. Research on resistance training points to roughly 1.6 grams per kilogram as the level where the benefit for building and keeping muscle flattens out. Protein also has the highest thermic effect of the three, costing 20% to 30% of its own calories to digest, and it does more for fullness per calorie than fat or carbohydrate.

Carbohydrates

Carbohydrates are classified as sugar, starch or fibre. Sugar is the simplest form; starch and fibre are complex. They are also grouped by how many saccharide units they contain: monosaccharides and disaccharides are the simple carbohydrates, while oligosaccharides and polysaccharides are the complex ones.

Glucose, a monosaccharide, is a primary energy source for humans and most other animals. Polysaccharides such as cellulose cannot be broken down by humans at all, but they still matter as dietary fibre, which supports digestion. Large amounts of sugar, which is what processed food tends to supply, carry real health costs. Complex carbohydrates from vegetables, fruit, whole grains and legumes, especially the ones that bring fibre with them, are useful and necessary.

The fibre target is about 14 grams per 1,000 calories eaten, which works out near 25 grams a day for women and 38 for men. Most people in Western countries eat around half of that. Fibre is the part of a carbohydrate target that changes how a diet feels, because it slows digestion and blunts the blood sugar response of the meal it arrives in.

Fat

Fats are molecules made largely of carbon and hydrogen. Cholesterol, phospholipids and triglycerides are the familiar examples. Dietary fat has a poor reputation it does not deserve: it has structural and metabolic jobs, it carries the fat-soluble vitamins A, D, E and K, and it is the body's most efficient way of storing energy.

Fats are classified by how their carbon atoms bond. The dietary categories that come up are saturated, unsaturated, trans, monounsaturated, polyunsaturated and omega-3 fatty acids. Saturated and trans fats are generally treated as the ones to limit, while monounsaturated, polyunsaturated and omega-3 fats are the better sources.

The Dietary Guidelines for Americans recommend avoiding trans fats wherever possible, keeping saturated fat under 10% of daily calories, and replacing saturated fat with monounsaturated and polyunsaturated fat rather than with refined carbohydrate. Trans fats have largely left the US food supply since the FDA removed partially hydrogenated oils from the generally-recognised-as-safe list in 2018. The same guidelines cap added sugars at under 10% of calories.

Fat also has a floor. Below about 20% of calories it becomes difficult to absorb fat-soluble vitamins properly and hormone production suffers, which is why the accepted range starts there rather than at zero.

Daily calorie needs

Calorie needs depend on height, weight, age, activity and whether you want to hold, lose or gain weight. The calculator estimates basal metabolic rate or resting daily energy expenditure first, then multiplies by an activity factor.

The Mifflin-St Jeor equation predicts BMR from weight, height, age and sex, and is the widely adopted default. The Katch-McArdle formula predicts resting daily energy expenditure from lean body mass instead, which makes it more accurate for leaner people who know their body fat percentage, and useless for anyone who does not.

Calories = BMR x activity factor + goal adjustment

where:

• activity factor runs from 1.2 for sedentary to 1.9 for very intense daily training or a physical job
• goal adjustment is 0 to maintain, or 250, 500 and 1,000 calories either side for half a pound, a pound and two pounds a week

Depending on all of it, an average person needs somewhere between 1,600 and 3,000 calories a day. Recommendations run higher for men, roughly 2,000 to 3,000, than for women at 1,600 to 2,400, and activity moves the figure more than anything else on the list.

Splitting calories into macros

Grams = calories x percentage / calories per gram

A 25-year-old man of 5 feet 10 inches and 165 pounds, exercising four or five times a week, has a BMR of 1,740 and a maintenance figure of 2,549 calories. On a 30% protein, 30% fat, 40% carbohydrate split that is 191 g of protein, 85 g of fat and 255 g of carbohydrate. Shift to a lower-carb 40/40/20 split and the same 2,549 calories become 255 g protein, 113 g fat and 127 g carbohydrate.

The Institute of Medicine publishes Acceptable Macronutrient Distribution Ranges, which is the evidence-backed boundary rather than a single prescription: 10% to 35% of calories from protein, 20% to 35% from fat, and 45% to 65% from carbohydrate. Any split inside those ranges is defensible. The calculator prints your grams against the AMDR range so you can see when a split has moved outside it, which the lower-carb option does on purpose.

For weight change, total calories do the work and the split does not. Controlled feeding studies that match calories and protein find very little difference in fat loss between low-carbohydrate and low-fat diets. What the split changes is how easy the diet is to stick to, how training feels, and how full you are, and those are the things that decide whether anyone lasts more than a month.

Macronutrients in common foods

Food	Serving	Protein	Carbs	Fat
Apple	1 (4 oz)	0.3 g	14.4 g	0.2 g
Banana	1 (6 oz)	1.9 g	38.9 g	0.6 g
Broccoli	1 cup	2.6 g	6.0 g	0.3 g
Carrots	1 cup	1.2 g	12.3 g	0.3 g
Beef, regular, cooked	2 oz	14.2 g	0 g	10.4 g
Chicken, cooked	2 oz	16.0 g	0 g	1.8 g
Tofu	4 oz	7.8 g	2.7 g	3.1 g
Egg	1 large	6.3 g	0.4 g	5.0 g
Shrimp, cooked	2 oz	15.5 g	0.7 g	1.3 g
Bread, white	1 slice (1 oz)	1.9 g	12.7 g	0.8 g
Butter	1 tablespoon	0.1 g	0 g	11.5 g
Caesar salad	3 cups	16.3 g	21.1 g	45.9 g
Cheeseburger	1 sandwich	14.8 g	31.8 g	15.2 g
Pizza	1 slice (14 in)	13.3 g	34.0 g	12.1 g
Potato	6 oz	4.5 g	36.5 g	0.2 g
Rice	1 cup cooked	4.2 g	44.1 g	0.4 g
Milk (whole)	1 cup	7.9 g	11.0 g	7.9 g
Orange juice	1 cup	1.7 g	25.8 g	0.5 g
Yogurt (low-fat)	1 cup	12.9 g	17.3 g	3.8 g
Beer	1 can	1.6 g	12.6 g	0 g

The Caesar salad row is worth a second look. It carries more fat than a cheeseburger, almost entirely from the dressing, which is the sort of thing macro tracking surfaces and calorie counting alone does not.

Hitting the numbers in practice

Nobody hits three targets exactly. Getting within about 10 grams on protein and roughly right on the other two is enough for the split to do its job.

Protein is the one worth aiming at deliberately, because it is the hardest to reach by accident and the one carrying most of the benefit for body composition. Fat and carbohydrate can be treated as the remainder, split however suits your appetite and training. Set protein first, set fat to at least 20% of calories, and let carbohydrate fill the gap.

The figures returned here are estimates built on standards from bodies including the Academy of Nutrition and Dietetics, the Centers for Disease Control and Prevention and the World Health Organization. They describe an average person. Hold a target for two or three weeks, watch what actually happens to your weight and how you feel, and adjust from there rather than from the equation.