Macro Calculator
Turn your calorie target into a protein, carb and fat split.
Updated October 2026
Calculated in your browser with the Mifflin-St Jeor equation. Your inputs are not saved unless you choose to sign up. AI estimates, not medical advice.
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Read the full disclaimer
Every number on this page (calorie targets, macro splits and any suggested meal plan) is produced by formulas (Mifflin-St Jeor for basal metabolic rate, standard activity multipliers) or, for AI-generated meal plans, by a language model applying those same formulas. On meal-plan pages the carbohydrate figure for each meal is calculated by difference: total calories minus protein and fat calories, divided by 4. It is not measured or estimated on its own, so read it as an arithmetic balance and not as an independent nutritional analysis of the dish. None of it is individualized medical or nutritional advice, and none of it has been reviewed by a registered dietitian, physician or other licensed healthcare professional.
Ask your doctor or a registered dietitian what is right for you before starting a new diet, especially if you are pregnant or breastfeeding, have a diagnosed medical condition, take prescription medication, or have a history of disordered eating. If you have kidney disease or another medical condition, ask your clinician before raising protein.
Mealyno never recommends a calorie target below your calculated Basal Metabolic Rate (BMR), the minimum energy your body needs at complete rest. Even the most aggressive weight-loss setting is clamped at that floor.
Calorie and BMR estimates use the Mifflin-St Jeor equation (Mifflin MD, St Jeor ST, et al. Am J Clin Nutr. 1990).
Generated: October 2026
A calorie target tells you how much to eat; a macro split tells you what to eat it as. Protein, carbohydrate and fat all provide energy, but they behave very differently in the body - protein is the macro most people find keeps them fuller for longer, fat supports hormone production, and carbohydrate fuels your brain and your training. Hitting a calorie number while ignoring the split behind it is a common reason people feel constantly hungry on an otherwise reasonable diet.
This calculator uses a protein-priority approach rather than fixed generic percentages (the common but crude "40/30/30" style advice). Protein is set first, scaled to your body weight and goal: about 2.2 g per kilogram for a muscle-building phase, 2.0 g per kilogram during a weight-loss phase (the top of the range published for exercising adults, used while eating in a deficit), and 1.6 g per kilogram for maintenance or general weight gain - all within or above the range generally supported by sports-nutrition research for people who train. Fat is set next at roughly 0.8-0.9 g per kilogram, enough to support normal hormone function. Whatever calories remain after protein and fat are accounted for go to carbohydrate, which is why carb grams are the ones that swing the most between a deficit and a surplus.
Every gram target here converts back to calories using the standard 4 kcal/g for protein and carbohydrate and 9 kcal/g for fat, and the three should sum to within a few kilocalories of your total calorie target - if you ever see a macro calculator whose numbers do not add back up to the stated calorie total, that is worth being suspicious of. This one is checked against the same total on every calculation.
As with every number on this page, this is a formula-based estimate, not an individualized nutrition plan, and it has not been reviewed by a registered dietitian. It is a solid, well-reasoned starting point grounded in the protein research that most calculators skip - adjust from there based on how your training, hunger and body composition respond over the following weeks, and check with a professional if you have specific medical or performance needs.
How the calculation works
- Protein (g) = bodyweight(kg) x 2.2 (build-muscle), x2.0 (losing weight), or x1.6 (maintain/gain).
- Fat (g) = bodyweight(kg) x 0.8-0.9, depending on goal.
- Carbohydrate (g) = (calorie target - protein kcal - fat kcal) / 4, so carbs absorb whatever calories protein and fat do not use.
Worked example
For the same man on the steady weight-loss goal, the calorie target is 2,329 kcal. Mealyno's in-app protein setting in a deficit is 2.0 g per kilogram, so protein is 80 x 2.0 = 160 g, or 640 kcal. Fat is set at about 0.8 g per kilogram: 64 g, or 576 kcal.
Carbohydrate takes what is left: (2,329 - 640 - 576) / 4 = 278 g. The three add back to about 2,328 kcal, within rounding of the target.
For a 35-year-old woman with 65 kg on the steady weight-loss goal, the calorie target is 1,572 kcal. The in-app protein setting gives 65 x 2.0 = 130 g, fat is about 52 g, and carbohydrate takes the remaining 146 g. Protein is 33% of her calories.
What to do with this number
The protein figure here follows the same setting as the Mealyno app: 2.0 g per kilogram in a deficit, 2.2 for building muscle and 1.6 otherwise. Published ranges are lower for some goals, and the protein calculator shows them with their sources so you can compare.
To see the split as food, open the plan nearest to your calories. For the example, 2,329 kcal is closest to the 2200 kcal plan.
Keep in mind what the number is: a formula-based estimate for a healthy adult, worked out in your browser and not reviewed by a doctor or dietitian. Use it to plan, then watch how you feel and how your weight trends over a few weeks, and adjust. If anything about it looks wrong for your situation, or you have a medical condition, ask a clinician before you change what you eat.
Macro calculator questions
How does the calculator set protein?
Protein is set first from your body weight and goal: 2.2 g per kilogram for building muscle, 2.0 g per kilogram in a weight-loss phase and 1.6 g per kilogram otherwise. This is the same setting the Mealyno app uses.
Why is this higher than the ranges I see elsewhere?
Published guidance gives ranges, and for weight loss a joint advisory suggests 1.2 to 1.6 g per kilogram. The app default sits at the top of the range published for people who exercise. The protein calculator shows the published ranges with their sources.
How is fat decided?
Fat is set at about 0.8 g per kilogram, or 0.9 when building muscle. That leaves room for protein and carbohydrate while keeping fat at a level most people find easy to plan around.
Do I have to hit every number exactly?
No. Treat the grams as a target zone. Being a few grams off on any macro on a given day changes very little, and the calorie total matters more.
Why do the macros add back to the calorie target?
Because they are calculated to. Protein and carbohydrate count 4 kcal per gram and fat counts 9, and carbohydrate takes whatever calories are left. If a calculator's numbers do not add up, be careful with it.
Is this a medical plan?
No. It is a formula-based estimate and has not been reviewed by a doctor or dietitian. If you have a medical condition, including kidney disease, ask your clinician before changing your protein intake.
Can I change the split?
You can use the numbers as a base and move calories between carbohydrate and fat if you prefer. Keep protein where you have set it and keep the total calories the same, so the day still adds up.
Where do the fibre and water numbers come from?
Fibre is set at 14 g per 1,000 kcal or 30 g, whichever is higher. They are general targets, and they are shown alongside the macros so the day is complete.
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