Macro calculator
Free macro calculator that splits daily calories into protein, fat, and carb grams. Supports cut, maintain, bulk, keto, low-carb, and high-protein presets.
A macro calculator splits your daily calorie target into protein, fat and carbohydrate, so you have a number to aim at for each. "Eat 2,500 calories" is hard to act on. "About 165 g protein, 75 g fat and the rest in carbs" is something you can plan meals around.
This tool sets protein first (2.2 g per kg of body weight, capped at the weight a BMI of 25 implies for your height), fat second (75 g by default, held between 20% and 35% of calories and reduced when protein needs the room), and lets carbs fill whatever calories are left. Protein goes first because it does the most for the muscle you're trying to keep or build. MuscleBuddy uses the same order, then adjusts the numbers against your weigh-in trend.
Estimated with the NASEM 2023 Estimated Energy Requirement, fitted on measured total daily energy expenditure. Mifflin-St Jeor with a standard activity multiplier gives 2633 kcal/day for the same goal. It estimates resting energy, and its multipliers sit below what most adults measurably burn, so it is shown for comparison only.
How this works
The calculator runs in two stages. First it computes your maintenance calories (TDEE) from the NASEM 2023 Estimated Energy Requirement for your age, with the Mifflin-St Jeor BMR formula times an activity factor shown beside it for comparison, then it adjusts that baseline by 500 kcal down for a cut or up for a bulk. That gives you a calorie target.
Stage two converts the calorie target into macro grams in a fixed order:
- Protein: 2.2 g per kg of body weight (≈1 g per pound), the figure Morton and colleagues' 2018 meta-analysis suggests for lifters; 2.7 g/kg on the high-protein preset. Above a BMI of 25 the per-kg figure is outside the population it was measured on, so it is applied to the weight a BMI of 25 implies for your height instead.
- Fat: 75 g baseline, capped at 35% of calories so a tight target cannot turn a standard split into a zero-carb one, and raised to at least 20% of calories on a large target. High-carb sets fat at 20% of calories. Keto and low-carb hold carbs instead (keto at the lower of 50 g and 10% of calories, low-carb at the lower of 130 g and 26%) and fat fills the rest. Fat is also what yields when protein and fat together would overshoot the calorie target.
- Carbs: fill the remaining calories, often 200–400 g for a lifter on a standard split.
Protein stays high on a cut and a bulk alike. In a deficit it helps you hold on to lean mass, and in a surplus it supplies the muscle you're trying to add.
Fat starts from a gram figure so a cut does not drive it toward zero: a 2021 meta-analysis of six small trials (Whittaker and Wu) found low-fat diets lowered testosterone in men. A flat gram figure becomes a bigger share as calories fall, so it is capped at 35% of calories and gives way to protein when the two cannot both fit.
Carbs take up the slack because they affect how your training feels more than the other two and are the easiest to move up and down with the calorie target. Carb cycling (more on training days, less on rest days) applies the same idea on a schedule.
Frequently asked questions
- How much protein do I need to build muscle?
- A 2018 meta-analysis of 49 resistance-training trials (Morton and colleagues) found extra protein stopped adding measurable muscle around 1.6 g per kilogram of body weight, with an upper estimate near 2.2 g/kg (roughly 0.7–1.0 g per pound), and the authors suggest about 2.2 g/kg for lifters after the most muscle. MuscleBuddy uses 2.2 g/kg, or 2.7 g/kg on the high-protein preset. The 2.2 g/kg figure comes from studies of mostly normal-weight adults, so above a BMI of 25 the app applies them to the weight a BMI of 25 implies for your height rather than to your current weight. In the app, a recent body-composition reading switches protein to a lean-mass basis instead: 2.75 g per kg of lean mass, or 3.1 g/kg on the high-protein preset.
- Why does fat start at 75 grams in the standard split?
- A 2021 meta-analysis of six small trials (Whittaker and Wu) found low-fat diets lowered testosterone in men, and fat carries the fat-soluble vitamins, so the US Dietary Reference Intakes put the adult range at 20% to 35% of calories. 75 g is our default, not a published figure, and it sits above 20% of calories for most adult targets. It is a starting point: the calculator keeps fat between 20% and 35% of calories, so on a low target it drops below 75 g, and it gives way to protein when the two would overshoot the target together.
- Do I need to track carbs strictly?
- Carbs fill the calories left after protein and fat are set. Hitting your calorie and protein targets matters more than an exact carb number, though eating enough carbs around training helps you train hard.
- What is a keto macro split?
- A ketogenic diet keeps carbs low enough, usually 20–50 g a day, that fat becomes most of your calories. The keto preset keeps protein at the usual figure, holds carbs at the lower of 50 g and 10% of calories, and fills the rest with fat.
- Should I eat the same macros every day?
- Constant macros are the easiest to stick to and work for most cuts and bulks. Some lifters prefer carb cycling (more carbs on training days) or periodic refeeds on a long diet. Weekly calories and protein drive the result, so pick the pattern you can keep.
- How often should I update my macro targets?
- Every 4–6 weeks, or sooner if your weigh-in trend stalls or moves faster than you planned. Your body weight changes, so the targets that fit a month ago drift out of date.
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