How to Calculate Macros: Protein, Carbs and Fat per Day

Learning how to calculate macros turns a vague eating plan into clear daily numbers. Instead of guessing how much protein, carbohydrate and fat you should eat, you start from your total daily energy expenditure and divide it into three targets you can actually follow. This guide explains that process step by step, so you can work out your own figures with confidence and check them against the Macro Calculator whenever you want a quick result.

Macros, short for macronutrients, are the three nutrients that supply almost all of your food energy: protein, carbohydrates and fat. Alcohol also supplies energy, but it is not counted as a macro in this kind of plan. Once you know your daily calorie target and the percentage split you want, converting those percentages into grams is simple arithmetic, and that is exactly what this guide will show you.

The Method / Formula

The method has three stages. First, estimate your basal metabolic rate, or BMR, which is roughly the energy your body uses at rest to keep you alive. The tool uses the Mifflin-St Jeor equation. For men, BMR is 10 times weight in kilograms, plus 6.25 times height in centimetres, minus 5 times age in years, plus 5. For women, the same calculation ends with minus 161 instead of plus 5.

Second, multiply BMR by an activity factor to get your total daily energy expenditure, or TDEE. This is an estimate of the calories you burn in a typical day, including movement, work and exercise. A sedentary factor is the lowest, while a very active factor is the highest, so choosing an honest activity level matters more than getting every other detail perfect.

Third, adjust TDEE for your goal and split the result between the three macros. For maintenance, you use TDEE unchanged. For a cut, you multiply TDEE by 0.85, which creates a 15 percent deficit. For a bulk, you multiply TDEE by 1.10, which adds a 10 percent surplus. The standard splits used by the tool are then applied to that goal calorie figure.

• Maintain: 30 percent protein, 40 percent carbohydrate and 30 percent fat.
• Cut: 40 percent protein, 35 percent carbohydrate and 25 percent fat.
• Bulk: 30 percent protein, 45 percent carbohydrate and 25 percent fat.

Finally, turn calories into grams using the energy each macro supplies. Protein provides 4 kilocalories per gram, carbohydrate provides 4 kilocalories per gram, and fat provides 9 kilocalories per gram. That is why fat grams are always much lower than protein or carbohydrate grams, even when fat supplies a similar share of calories. The formulas are: protein grams equal calories times protein percentage divided by 4, carbohydrate grams equal calories times carbohydrate percentage divided by 4, and fat grams equal calories times fat percentage divided by 9.

How to Calculate Macros Step by Step

1. Write down your sex, age, weight in kilograms and height in centimetres.
2. Work out your BMR with the Mifflin-St Jeor equation for your sex.
3. Multiply BMR by your activity factor to get your TDEE.
4. Adjust TDEE for your goal: keep it the same to maintain, multiply by 0.85 to cut, or multiply by 1.10 to bulk.
5. Choose your split for that goal, such as 30, 40 and 30 percent for maintenance.
6. Convert each share into grams by dividing protein and carbohydrate calories by 4 and fat calories by 9, then round to whole grams for everyday use.

Worked Example

Take the example shown on the tool page: a man aged 30 years, weighing 70 kg, measuring 175 cm, moderately active, with a goal of maintaining his weight. His TDEE is 2,555.56 kcal per day. Using the maintain split of 30 percent protein, 40 percent carbohydrate and 30 percent fat, the working is as follows.

• Protein: 2,555.56 times 0.30 divided by 4 equals 191.67 g per day.
• Carbohydrates: 2,555.56 times 0.40 divided by 4 equals 255.56 g per day.
• Fat: 2,555.56 times 0.30 divided by 9 equals 85.19 g per day.

Those three figures add up to the full 2,555.56 kcal, which is a useful check. Protein supplies about 767 kcal, carbohydrates supply about 1,022 kcal, and fat supplies about 767 kcal. If you switch the same person to a cut, the calorie target would fall to about 2,172 kcal, and the higher 40 percent protein share of the cut split would protect muscle while the deficit does its work. If he bulked instead, the target would rise to about 2,811 kcal, with extra carbohydrate supplying most of the additional energy.

Common Mistakes / Good to Know

• Do not split your BMR instead of your TDEE. BMR covers rest only, so using it as your calorie target will leave you well short of the energy you actually burn in a day.
• Do not divide fat calories by 4. Fat supplies 9 kcal per gram, so using 4 would more than double your fat target and throw the whole plan out of balance.
• Do not forget the goal adjustment. The same TDEE cannot serve maintenance, cutting and bulking at once; apply 0.85 for a cut or 1.10 for a bulk before you split the calories.
• Do not chase exact grams every single day. These are estimates, not laboratory measurements, so treat them as daily targets with a small range of about 5 percent. Weekly consistency matters more than hitting every gram on any one day, and you should adjust the targets if your weight moves in an unexpected direction over several weeks.

For an instant check, try the TDEE Calculator, and read our related guide How to Calculate TDEE for a closer look at the first stage of this method.

Frequently Asked Questions