Macro Calculator
Takes your daily calorie target and body weight and splits it into protein, fat, and carbohydrate. The logic is that protein and fat have floors driven by physiology while carbohydrate is whatever calories remain, which is a more defensible approach than fixed percentage splits.
How to use it
- Enter your TDEE in kilocalories.
- Enter your body weight in kilograms.
- Choose cut, maintain, or bulk.
- Read the daily calorie target and gram targets for each macronutrient.
Calories per gram, and why the split matters
Protein and carbohydrate both provide 4 kcal per gram, fat provides 9, and alcohol provides 7. So a gram of fat carries more than twice the energy of a gram of protein, which is why fat intake moves the calorie total quickly.
Total calories determine whether you gain or lose weight. The macronutrient split determines what you gain or lose, how full you feel, and how well you train — which is why the split is worth getting roughly right even though it is secondary to the total.
Fixed percentage splits such as 40/30/30 are popular and arbitrary. The problem is that a percentage of a large calorie budget and a percentage of a small one give very different absolute amounts, and protein requirements scale with body weight rather than with calorie intake. A 60 kg person cutting on 1,600 kcal and a 100 kg person bulking on 3,500 kcal do not need the same percentage of protein.
Protein is set by body weight
Protein requirements track lean mass, so the sensible unit is grams per kilogram of body weight.
Common targets:
- 0.8 g/kg is the minimum to prevent deficiency in a sedentary adult. It is a floor, not an optimum.
- 1.4 to 1.8 g/kg supports general training and body composition goals.
- 1.6 to 2.2 g/kg is the range where muscle protein synthesis is maximised in most studies for resistance-trained individuals.
- 2.2 to 3.0 g/kg is worth considering in a substantial deficit, where higher protein preserves lean mass and increases satiety while calories are low.
Fat has a floor
Fat is not optional. It is required for hormone production — testosterone and oestrogen synthesis both depend on adequate dietary fat — and for absorbing the fat-soluble vitamins A, D, E, and K.
A practical minimum is about 0.5 g/kg of body weight, or roughly 20 percent of calories, whichever is higher. Sustained intake below that is associated with reduced hormone levels, poor recovery, and in women menstrual disruption. Very low fat diets are a common and avoidable mistake in aggressive cuts.
A useful upper working range is around 35 percent of calories. Above that, carbohydrate gets squeezed enough to affect training performance in most people, though ketogenic approaches deliberately go much further and work for some individuals.
Within the total, the type matters more for health than for body composition. Adequate omega-3 intake and limited industrially produced trans fats are worth attention regardless of the split; saturated fat guidance has become more nuanced but moderation remains the mainstream position.
Carbohydrate is the flexible remainder
Carbohydrate is the only macronutrient with no strict dietary requirement — the body can produce glucose from protein and fat via gluconeogenesis. That does not make it unimportant, it makes it adjustable.
Carbohydrate is the preferred fuel for high-intensity work. Muscle glycogen powers anything above moderate intensity, and depleted glycogen shows up directly as reduced training capacity. Anyone doing substantial resistance training or interval work will perform better with carbohydrate available, and cutting it hard while trying to maintain training quality tends to fail.
The practical approach: set protein from body weight, set fat at or above its floor, and assign whatever calories are left to carbohydrate. In a bulk that remainder is generous. In an aggressive cut it can be small, which is the point at which reducing the deficit is usually better than cutting fat below its floor.
One accounting note: fibre is a carbohydrate but is poorly digested, so its net contribution is lower than 4 kcal per gram. Some systems track net carbohydrate by subtracting fibre. Either convention works as long as it is applied consistently, and a target of 25 to 35 g of fibre a day is worth hitting for reasons unrelated to the macro split.
At a glance
| Energy density | Protein and carbs 4 kcal/g, fat 9 kcal/g |
|---|---|
| Protein target | 1.6 to 2.2 g/kg for trained individuals |
| Fat floor | About 0.5 g/kg or 20 percent of calories |
| Carbohydrate | The remaining calories |
Frequently asked questions
How much protein do I need?
1.6 to 2.2 g per kg of body weight for resistance-trained individuals, and up to 3.0 g/kg in a substantial deficit to preserve lean mass.
Can I cut fat very low to fit more carbs?
Not below about 0.5 g/kg or 20 percent of calories. Fat is required for hormone production and fat-soluble vitamin absorption.
Do I need carbohydrate at all?
There is no strict requirement, since the body can make glucose from other sources. But glycogen fuels high-intensity work, so cutting it hard reduces training capacity.
Are fixed percentage splits like 40/30/30 useful?
Not particularly. Protein requirements scale with body weight, not with calorie intake, so a percentage gives the wrong absolute amount at high or low calorie targets.
Read more
Health and fitness math — Every formula here is an estimate with a known error band. Knowing the band is what makes them useful.