Calorie and macronutrient calculator for your goal
The calories you need a day to lose fat, maintain or build muscle, and the split of protein, fat and carbohydrate.
Calculator inputs
Results
Enter your values and press “Calculate” to see the result.
| Macronutrient | Grams | kcal per day | % of calories |
|---|---|---|---|
| Protein | 160 | 640 | 30 |
| Fat | 60 | 540 | 25 |
| Carbohydrates | 245 | 981 | 45 |
See the working step by step
- Basal metabolic rate = 1,742.50 kcal; total expenditure = 2,701 kcal
- Split: 29.62% protein, 25% fat, 45.38% carbohydrate
In short
- What it calculates
- The calories you need a day to lose fat, maintain or build muscle, and the split of protein, fat and carbohydrate.
- Formula used
BMR = 10 × weight + 6.25 × height − 5 × age + 5 (male) or − 161 (female)- Example
- Example 1. Losing fat.
Calorie and macro calculator
How many calories to eat depends on your expenditure and your goal: to lose fat, a little less than you burn; to build muscle, a little more. And how many of those calories are protein, fat or carbohydrate changes the outcome too.
Enter your details, pick the goal and the calculator estimates your total expenditure, the daily calories, the grams of each macronutrient and, if you give a target weight, the approximate weeks to get there. Everything runs in your browser.
How it works
Your basal metabolic rate is calculated with Mifflin-St Jeor and multiplied by the activity factor to get total expenditure. Depending on the goal, a percentage is subtracted or added: −25% or −20% to lose fat, +15% to build muscle.
Then the macronutrients are split: protein first (per kilo of body weight), then fat (a percentage of calories) and carbohydrates with what is left. Protein and carbohydrate give 4 kcal per gram and fat 9.
Formula
BMR = 10 × weight + 6.25 × height − 5 × age + 5 (male) or − 161 (female)
Total expenditure = BMR × activity factor
Calories = total expenditure × (1 + adjustment) adjustment: −25%, −20%, 0%, +15%
Protein (g) = weight × g/kg (2.0 if losing fat, 1.8 otherwise)
Fat (g) = calories × fat % ÷ 9 Carbohydrate (g) = (calories − 4 × protein − 9 × fat) ÷ 4
Weekly change ≈ (calories − expenditure) × 7 ÷ 7,700 (kg) Weeks = weight difference ÷ |weekly change|
Worked example
Example 1. Losing fat.
A 35-year-old man, 80 kg and 178 cm with moderate activity burns 2,701 kcal. To lose fat at −20%: 2,161 kcal a day, with 160 g of protein (2 g/kg), 60 g of fat and 245 g of carbohydrate. He would lose about 0.49 kg a week.
Example 2. Maintaining.
The same person, to maintain weight: 2,701 kcal, with 144 g of protein (1.8 g/kg), 75 g of fat and 362 g of carbohydrate.
Example 3. Building muscle.
A 24-year-old man, 70 kg and 180 cm with intense activity burns 2,950 kcal. With a 15% surplus: 3,392 kcal, 126 g of protein, 94 g of fat and 510 g of carbohydrate.
Example 4. With a target weight.
A 38-year-old woman, 85 kg and 170 cm with light activity burns 2,147 kcal; to lose fat at −20% she eats 1,718 kcal, loses about 0.39 kg a week and would take about 26 weeks to go from 85 to 75 kg.
Explanation
How goal calories are worked out
The starting point is your total energy expenditure (basal metabolic rate times your activity level). To lose weight you eat less than that; to build muscle, a little more; to maintain, the same.
What deficit makes sense?
- **−10% to −20%**: a moderate pace, easier to sustain and better at keeping muscle.
- **−25%**: faster but harder; needs high protein and strength training.
- More than 1% of body weight a week is not advised.
- Do not go below basal metabolism without professional supervision.
Macronutrients
- **Protein** (4 kcal/g): keeps and builds muscle; 1.6 to 2.2 g/kg is the usual range for active people.
- **Fat** (9 kcal/g): needed for hormones and fat-soluble vitamins; 20% to 35% of calories.
- **Carbohydrate** (4 kcal/g): the fuel for training; it takes up the rest of the calories.
Adjusting to reality
The calculation is a starting point. Track your weekly average weight for two to four weeks: if it is not changing as expected, adjust calories by 5–10%. The body adapts, so the pace of loss slows over time.
Common mistakes
- Overestimating the activity level.
- Setting too aggressive a deficit.
- Not counting drinks, oils or snacks.
- Expecting linear loss.
- Cutting protein when eating less.
Limits of this calculator
- It is an estimate for healthy adults; it is not for children, pregnancy, breastfeeding or illness.
- The 7,700 kcal per kilo rule is approximate and ignores metabolic adaptation.
- It gives no medical or micronutrient advice.
Notice
This is an estimate and does not replace advice from a doctor or dietitian. Consult a professional if you have a medical condition, take medication or have a history of eating disorders.
Frequently asked questions
How many calories should I eat to lose weight?
A 10% to 25% deficit on your total expenditure. The calculator gives the figure for your case. Do not go below basal metabolism without supervision.
How many calories to build muscle?
A small surplus, 5% to 15%, with high protein and strength training. A larger surplus adds more fat than muscle.
How much protein do I need?
Between 1.6 and 2.2 g per kilo of body weight in people who train; 2 g/kg is a good starting point when losing fat.
Why am I not losing weight at the pace the calculator says?
The calculator estimates; the body adapts and calories in food and exercise are usually miscounted. Adjust with your weekly average weight.
Which macro split is best?
The one you can keep up. What matters: enough protein, fat above 20% of calories and the rest in carbohydrate.
What does it mean when calories are below basal metabolic rate?
That the deficit is very aggressive for your case. Holding it without supervision is not advised; pick a smaller deficit.
How many weeks will it take to reach my weight?
It is an estimate using 7,700 kcal per kilo; in practice the pace slows over time, so allow somewhat more.
Is my data sent to a server?
No. The calculation runs in your browser.
Sources and references
The formula behind this calculator is not ours. These are the sources it comes from, in APA 7 format, in case you want to go to the original or cite them in your own work.
- Mifflin, M. D., St Jeor, S. T., Hill, L. A., Scott, B. J., Daugherty, S. A., & Koh, Y. O. (1990). A new predictive equation for resting energy expenditure in healthy individuals. The American Journal of Clinical Nutrition, 51(2), 241–247. https://doi.org/10.1093/ajcn/51.2.241 https://doi.org/10.1093/ajcn/51.2.241 The basal metabolic rate equation.
- Jäger, R., Kerksick, C. M., Campbell, B. I., Cribb, P. J., Wells, S. D., Skwiat, T. M., … Antonio, J. (2017). International Society of Sports Nutrition position stand: Protein and exercise. Journal of the International Society of Sports Nutrition, 14, Article 20. https://doi.org/10.1186/s12970-017-0177-8 https://doi.org/10.1186/s12970-017-0177-8 The protein recommendations for active people.
- Hall, K. D. (2008). What is the required energy deficit per unit weight loss? International Journal of Obesity, 32(3), 573–576. https://doi.org/10.1038/sj.ijo.0803720 https://doi.org/10.1038/sj.ijo.0803720 The limits of the 7,700 kcal per kilo rule.
Need to calculate something else?
These tools are often used alongside this calculator.
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BMR calculator
The calories your body burns at rest, with Mifflin-St Jeor, Harris-Benedict, Katch-McArdle and Cunningham…
Protein
The grams of protein you need for your weight and profile: low activity, active, strength or fat loss, or…
BMI
Your body mass index, your WHO category, the healthy weight range for your height and the waist-to-height…
Water intake
Recommended litres based on your weight, exercise and climate.
Ideal weight
Four classic formulas plus the healthy range from BMI.