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Macro Calculator

Created by Bogna Szyk, Rita Rain and Dominika Śmiałek, MD, PhD candidate
Reviewed by Adena Benn
Based on research by
Mifflin, M. D., St Jeor, S. T., Hill, L. A., Scott, B. J., Daugherty, S. A., Koh, Y. O. A new predictive equation for resting energy expenditure in healthy individuals; The American journal of clinical nutrition; 1990See 1 more source
Ryan-Harshman M, Aldoori W. New dietary reference intakes for macronutrients and fibre; Canadian Family Physician; 2006
Last updated: May 30, 2024

This macronutrient calculator, or macro calculator for short, is a comprehensive tool that can serve as your diet companion. After providing a few essential pieces of information, such as your current level of exercise or target weight, you will receive a detailed, week-by-week diet plan based on your macros intake. Additionally, you can scroll down for some tips on how to calculate macros or what is the optimal calorie deficit for a safe weight loss. We will also elaborate on the pros and cons of the IIFYM (If It Fits Your Macros) diet.

We created this calculator in cooperation with a dietitian Dorota Sokół, who runs the portal Przewodnik Żywienia about healthy nutrition.

Remember that no online tool can replace a personalized consultation with a professional dietitian. If you're planning on losing or gaining a lot of weight, be sure to schedule an appointment with an expert before attempting a drastic change in your eating habits!

We try our best to make our Omni Calculators as precise and reliable as possible. However, this tool can never replace a professional doctor's assessment. All information on this website is for informational purposes only and is not intended to serve as a substitute for medical consultation. Always consult your results with a health care provider.

What are macronutrients?

Macronutrients are food components we need to take in daily to ensure our bodies are working properly. Some macronutrients provide energy in the form of calories. In contrast, others, such as water or fiber, are required for different reasons – for example, to facilitate the proper functioning of the digestive system.

If you're interested in macros for weight loss or weight gain, you will be focusing primarily on the three types that produce energy. These are:

  • Proteins: these macros build our muscles but also play a key role in regulating our metabolism and hormones. Some proteins are also essential for the immune system. You can find them in meat, fish, and dairy products and in vegan foods such as nuts or beans.

  • Carbohydrates: the main reason we need to consume carbohydrates is to provide energy (see the calorie calculator) to our bodies. Simple carbohydrates, such as white bread or white sugar, will give you a short-term energy boost, but you will soon need to eat more. Your body needs more time to digest complex carbohydrates, such as fruits or vegetables, which means they will fill you up for a bit longer.

  • Fats: this third type of macros is by far the most efficient: while 1 gram of proteins or carbohydrates is equivalent to only 4 calories, 1 gram of fats contains 9 kcal. This is why fats serve as an energy reserve – if you cannot provide your body with as many calories as it needs, your fat tissue will begin to break up to supply additional energy. You can find fats in products such as oil, nuts, avocados, pizzas, and chips.

What should my macros be?

If you're trying to estimate the daily intake of each macronutrient, you need to take a few aspects into consideration. The first one is your required calorie intake. This value is different for each individual; we base it on factors such as age, sex, weight, or activity level (i.e., calories burned). Additionally, you need to adjust this value based on the target weight – intuitively, you will need to eat more if you want to gain weight and less in the case of planned weight loss.

Once you know the total number of calories you should consume each day, you can calculate how many of them should come from proteins, carbohydrates, and fats. You can use the following rules of thumb:

  • 10%-35% of all calories should come from proteins. A second recommendation, issued by the Food and Nutrition Council of the National Research Council, suggests consuming approximately 0.8 g of protein per kilogram of body weight per day.

  • 45%-65% of all calories should come from carbohydrates. Our macro calculator uses 60% as a recommendation. Additionally, you should limit simple sugars (such as sweets or white bread) to no more than 10% of your diet.

  • 20%-35% of all calories should come from fats. In the case of this macronutrient, it is essential to monitor the type of fats you consume. In general, you should minimize the amount of saturated fats (e.g., butter or cream) and trans fats (e.g., margarine) and use healthier unsaturated fat substitutes from sources such as nuts or avocados.

These numbers give you a good starting point in planning your diet, but be sure to distribute them between meals in a sensible way, too!

💡 Our meal calorie calculator can help with this task.

How to use the macronutrients calculator?

Our macro calculator finds your current calorie requirement based on the Mifflin-St Jeor equation:

  • BMR(men) = (10 × weight / 1 kg + 6.25 × height / 1cm - 5 × age / 1 year + 5) kcal / day

  • BMR(women) = (10 × weight / 1 kg + 6.25 × height / 1cm - 5 × age / 1 year - 161) kcal / day

This equation determines your basal metabolic rate (BMR) – the amount of energy that your body needs to sustain basic functions. As you can see above, the equation is different for men and women.

Once you know the BMR, you need to multiply its value by a factor corresponding to your physical activity level:

  • Sedentary lifestyle (little or no exercise): 1.2
  • Slightly active lifestyle (light exercise or sports 1-2 days/week): 1.4
  • Moderately active lifestyle (moderate exercise or sports 2-3 days/week): 1.6
  • Very active lifestyle (hard exercise or sports 4-5 days/week): 1.75
  • Extra active lifestyle (very hard exercise, physical job, or sports 6-7 days/week): 2
  • Professional athlete: 2.3

These calculations will result in the number of calories needed to maintain your current weight.

How to calculate macros for weight loss?

If you're planning to lose or gain weight, you will need to adjust the number obtained in the calculations described in the previous paragraph. It is typically assumed that each pound of body fat stores approximately 3500 kcal of energy. This is why you need a calorie deficit of 500 kcal a day to lose one pound or 0.5 kg a week. Naturally, if you want to gain weight, you will need to add the same amount of food to your diet. For more details, see the calorie deficit calculator.

If you want to calculate macros for your weight loss or gain, you need to input two additional pieces of information into this macro calculator:

  • The first one is your target weight – how much you want to weigh after your diet. You can use our BMI calculator to check what weight would be optimal for you or simply calculate the ideal weight according to four different formulas.

  • The second factor is the diet type. You can choose a regular diet that will help you lose one pound a week or a strict one that leads to losing two pounds every week. In most situations, you shouldn't cut more than 1000 calories a day from your diet – such a massive calorie deficit may have a terrible impact on your health.

Dietitians recommend never reducing your calorie intake below your Basal Metabolic Rate. Our macro calculator will display a warning if you are trying to plan a diet with a daily intake lower than the minimum allowable value.

Once you provide all the necessary information, two graphs will appear below the calculator. The first one shows how your weight will change over time. Remember that this is only an approximation – don't worry if the weight loss is not as regular as shown here!

The second graph shows the suggested calorie intake for each week of your diet plan. As your weight changes over time, so does the number of calories in your diet. The macro calculator dynamically determines a new value for each week, so you can make sure to always eat exactly as much as needed.

We try our best to make our Omni Calculators as precise and reliable as possible. However, this tool can never replace a professional doctor's assessment. Always consult your results with a health care provider.

🔎 This calculator has an alternative name – the IIFYM calculator, as it is based on the principles of the IIFYM (If It Fits Your Macros) diet.

What is the IIFYM diet?

The IIFYM (If It Fits Your Macros) diet tracks macronutrients rather than individual foods. This diet is based on the assumption that you can eat whatever you want as long as it fits your macros plan.

The main benefit of such a diet is its flexibility – after all, you're not bound to strict meal plans but can freely enjoy your favorite foods. Learning how to calculate macros also requires a bit less effort than learning the principles of the regular diet, so many people claim that IIFYM is more accessible.

You need to remember, though, that IIFYM has its downsides: it ignores the recommended intake of micronutrients, such as vitamins or minerals, and cannot be used in cases of unusual medical conditions. It is also not recommended by conventional dietitians. If you plan to start an IIFYM diet, it's a good idea to consult a professional to ensure you're not jeopardizing your health!


What is the basal metabolic rate (BMR)?

The basal metabolic rate (BMR) is the number of calories you burn daily while your body is at complete rest. It is also known as the resting metabolic rate (RMR) or resting energy expenditure (REE). You can estimate your BMR by using the Mifflin-St Jeor equation.

How do I compute my BMR if I am a 40 year old lady?

To compute the basal metabolic rate:

  1. Recall the Mifflin-St Jeor equation for women: BMR = (10 × weight [kg] + 6.25 × height [cm] - 5 × age [yrs] - 161) kcal/day.
  2. Collect the missing data: weight and height of the lady in question.
  3. Plug the data into the equation.
  4. Execute the computation to get the answer.

How many carbs should I eat if I am a 25 years old female and weigh 60 kg?

The answer depends on your energy expenditure, which in turn depends on your age, height, and level of physical activity. Assuming you measure 170 cm and have an average activity level, to maintain your weight, you should eat about 250-350 g of carbs per day.

Bogna Szyk, Rita Rain and Dominika Śmiałek, MD, PhD candidate
Personal details
Activity level
Light exercise 1-2 times/week
Maintain weight
Calories to maintain weight
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