Reviewed by: Kateryna Kozak, Master’s degree holder from Kamianets-Podilskyi Ivan Ohiienko National University, majoring in Physical Culture and Sports; ExpertX-certified dietitian and nutritionist; internationally certified EREPS trainer; multiple-time bodybuilding champion in the Fitness Bikini category; speaker at the Proper Nutrition fitness forum.
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The calculator works out your daily calorie target and macros — calories, protein, fat and carbohydrates. Below is how the calculation works, where the numbers come from and what to do with them.
What are calories and macros
Calories, protein, fat and carbohydrates are the four numbers that determine how much energy your body gets from food and whether it has enough nutrients to function properly.
A common mistake is assuming that eating less is enough to lose weight. What matters is not only total calories but the balance of macronutrients. Two people can eat the same number of calories and get different results: the one eating enough protein keeps their muscle mass, the one falling short loses it along with the fat.
Calories
A calorie is a unit of energy. Your body spends it on heart function, breathing, brain activity, maintaining body temperature, physical activity and recovery. Even at complete rest the spending never stops — that is your basal metabolic rate (BMR).
Depending on the balance between calories consumed and calories burned there are three modes:
- Deficit — less comes in than goes out. The body uses its own reserves and weight gradually falls.
- Maintenance — intake roughly equals expenditure, weight stays stable.
- Surplus — more comes in than goes out. Used for building muscle mass.
Protein
The main building material: muscle growth and repair, enzyme synthesis, hormone production, immune function, tissue regeneration.
Enough protein matters most for people losing weight, training regularly or trying to keep muscle during a calorie deficit. Falling short leads to muscle loss, slower recovery after training and constant hunger.
High-protein foods (per 100 g)
| Food | Protein, g | Calories, kcal |
|---|---|---|
| Chicken breast (boiled) | 21 | 165 |
| Lean beef | 26 | 187 |
| Tuna | 25 | 132 |
| Hard cheese | 25 | 350 |
| Lentils (dry) | 24 | 353 |
| Salmon | 22 | 208 |
| Cottage cheese 5% | 17 | 121 |
| Chicken egg | 13 | 155 |
| Greek yoghurt 2% | 10 | 73 |
Fat
Fat is often treated as harmful, yet it is essential: hormone production, absorption of vitamins A, D, E and K, nervous system function, protection of internal organs, skin and hair health.
Cutting it out entirely is a bad idea. What matters far more is choosing good sources: avocado, nuts, seeds, oily sea fish, vegetable oils.
Carbohydrates
The main energy source for the brain, muscles and central nervous system, and for everyday activity.
Simple carbs are absorbed quickly and give a short energy spike — sugar, sweets, pastry, sugary drinks. Complex carbs are absorbed more slowly and keep you full longer — grains, vegetables, legumes, wholegrain products, potatoes, durum wheat pasta.
Why calculate your macros
For weight loss. A calculated target lets you build a moderate deficit without punishing diets — losing weight gradually while keeping your muscle and feeling normal.
For weight maintenance. The calculator shows how many calories and macronutrients you need to hold your current shape.
For building muscle. Strength training demands more energy and protein. The calculation helps you plan a diet for muscle growth without excess fat gain.
For nutrition quality. Even with no weight goal, tracking macros helps balance your diet and avoid nutrient shortfalls.
Calculation formulas
Mifflin-St Jeor formula
The main formula, developed in 1990. Considered the most accurate for people with normal and excess weight — this is the one our calculator uses.
Harris-Benedict formula (revised, 1984)
Katch-McArdle formula
For those who know their body fat percentage — it accounts for lean body mass, so it is more accurate for people with a high muscle percentage:
Activity multipliers
BMR shows expenditure at rest. To get total daily energy expenditure (TDEE) it is multiplied by an activity factor:
| Activity level | Factor | Who it fits |
|---|---|---|
| Sedentary | 1.2 | Desk job, no training |
| Light | 1.375 | 1–3 sessions a week |
| Moderate | 1.55 | 3–5 sessions a week |
| High | 1.725 | 6–7 sessions a week |
| Very high | 1.9 | Physical job + daily training |
Worked example
Man, 30 years old, 180 cm, 85 kg, moderate activity, goal — weight loss.
Step 1. Basal metabolic rate (BMR)
Step 2. Total daily expenditure (TDEE)
That is what it takes to maintain the current weight.
Step 3. A 20% deficit
Step 4. Macro split
| Nutrient | Amount | Kcal | Share |
|---|---|---|---|
| Protein | 153 g (1.8 g/kg) | 612 | 27% |
| Fat | 77 g (0.9 g/kg) | 689 | 30% |
| Carbs | 242 g | 969 | 43% |
Additional numbers: BMI = 85 ÷ 1.8² = 26.2 (overweight), water intake ≈ 2.5 L per day.
At that deficit the expected weight loss is roughly 0.5 kg per week. For women the calculation is the same, only the constant in the formula changes.
Macro targets by goal
| Goal | Protein | Fat | Carbs |
|---|---|---|---|
| Weight loss | 1.6–2.2 g/kg | 0.8–1.0 g/kg | remaining calories |
| Maintenance | 1.2–1.6 g/kg | 1 g/kg | remaining calories |
| Muscle gain | 1.6–2.2 g/kg | 1.0–1.2 g/kg | remaining calories |
Protein and fat are calculated from body weight first, then carbohydrates fill the remaining calories.
BMI ranges
Body mass index roughly assesses whether your weight matches your height. It does not account for the ratio of muscle to fat, so it can be inflated for athletes — treat it as a reference point, not a diagnosis.
| BMI | Category |
|---|---|
| below 18.5 | Underweight |
| 18.5–24.9 | Normal |
| 25–29.9 | Overweight |
| 30–34.9 | Obesity class I |
| 35–39.9 | Obesity class II |
| 40 and above | Obesity class III |
How to use the results
Do not create an excessive deficit. The optimal range is 10–20% of TDEE. Sharper cuts lead to muscle loss, fatigue and burnout. Diets below 1200 kcal (women) and 1500 kcal (men) should not be self-prescribed.
Keep protein up. It preserves muscle mass and keeps you full longer — which makes a deficit easier to stick to.
Do not cut out fat. It is needed for hormonal balance and the absorption of fat-soluble vitamins.
Recalculate periodically. After a 3–5 kg change in weight or a change in activity level your target shifts — the calculation is worth updating.
Common tracking mistakes
- Ignoring snacks. A handful of nuts is 150–200 kcal.
- Not weighing food. Eyeballing portions gives up to 30% error.
- Forgetting drinks. A syrup latte is 200–300 kcal, a glass of wine around 150.
- Ignoring cooking oil. One tablespoon is over 100 kcal.
- Expecting instant results. Weight fluctuates with water, cycle and gut contents. Judge by the 2–3 week trend, not daily changes.
Who this calculator is not for
The calculation is for reference only and does not replace medical advice. Do not use it on your own if you are:
- under 18 years old;
- pregnant or breastfeeding;
- living with diabetes;
- living with kidney or liver disease;
- with a history of disordered eating;
- with a BMI below 18.5.
In these cases daily calorie needs are determined by a doctor or dietitian based on your health status.
Frequently asked questions
What does KBZHU mean?
KBZHU is the Ukrainian and Russian shorthand for calories, protein, fat and carbohydrates in a daily diet. An online calculator works this out automatically.
How do you calculate your macros?
First the basal metabolic rate is found using the Mifflin-St Jeor formula, then multiplied by an activity factor (1.2–1.9) and adjusted for your goal: minus 10–20% for weight loss, plus 10–15% for muscle gain.
How many calories do you need to lose weight?
Usually a deficit of 10–20% of daily expenditure — roughly 300–500 kcal per day and a loss of 0.3–0.5 kg per week. The exact figure depends on your parameters: for a woman with a desk job it is around 1600–1800 kcal, for an active man 2300–2600 kcal.
How much protein per kilogram of body weight?
For weight loss and muscle gain — 1.6–2.2 g per kg of body weight, for maintenance 1.2–1.6 g. For an 85 kg man in a deficit that is roughly 150 g of protein per day.
What is the difference between KBZHU and BZHU?
They are the same thing; the difference is only whether the letter for calories is included in the abbreviation. BZHU is protein, fat and carbs; KBZHU adds total calories.
What is a calorie deficit?
A state where the body gets less energy from food than it spends and covers the difference from its own reserves. A moderate deficit is 10–20% of TDEE.
Do protein, fat and carbs need to be tracked separately?
Yes. At the same calorie intake a different macronutrient split gives a different outcome: enough protein preserves muscle during weight loss, too little does not.
How often should macros be recalculated?
After a 3–5 kg change in weight or a change in physical activity level. On average once every 1–2 months.
Can you lose weight without counting calories?
Yes, if the deficit arises naturally through a change in what you eat. Counting simply makes the process predictable and helps you understand why the weight has stalled.
Why is my weight not changing in a deficit?
Most often because of inaccurate tracking (unweighed portions, forgotten drinks and oil). Other causes: water retention, cycle phase, reduced everyday activity. If the weight holds for more than 3 weeks with accurate tracking, revisit the calculation or consult a professional.
Can you eat carbs in the evening?
Yes. The timing of carbohydrates does not affect weight gain — total daily calories are what count.
Do vegetables need to be counted?
Yes, although most non-starchy vegetables contain 20–40 kcal per 100 g. What matters far more is the oil you dress them with.
Does the calculator work for both men and women?
Yes, sex is part of the formula: the constant is +5 for men and −161 for women.
Can you use the calculator without doing any sport?
Yes, that is what the "Sedentary" activity level is for (factor 1.2) — it matches a desk job with no training.
Conclusion
Knowing your macros makes eating deliberate: once you know your daily calorie target and the recommended amounts of protein, fat and carbohydrates, it is far easier to move toward your goal — losing weight, holding your shape or building muscle.
The numbers are a reference point, not a finished plan. If you need an individual programme that accounts for your health, schedule and eating habits — book a consultation.
