Free Macro Calculator
Get evidence-based protein, fat, and carb targets tailored to your body and goals. Backed by peer-reviewed research from the ISSN, Morton et al., and Helms et al.
Improves accuracy using the Katch-McArdle formula and lean-mass-based protein targets.
How This Macro Calculator Works
This calculator uses a four-step process grounded in sports nutrition research. First, it estimates your Basal Metabolic Rate (BMR) using the Mifflin-St Jeor equation — or the Katch-McArdle equation if you provide your body fat percentage. Then it multiplies your BMR by an activity factor to get your Total Daily Energy Expenditure (TDEE). Next, it adjusts calories for your specific goal (deficit, surplus, or maintenance). Finally, it distributes those calories across protein, fat, and carbohydrates using evidence-based targets.
If you want to see your TDEE in more detail with calorie targets for multiple goals at once, use our TDEE calculator. For a detailed fat loss plan with a timeline and weekly targets, try the calorie deficit calculator.
Protein: The Most Important Macro for Lifters
Protein is the building block of muscle tissue and the most critical macronutrient for anyone who lifts weights. A 2018 meta-analysis by Morton et al., pooling data from 49 studies and 1,863 participants, found that 1.6 g/kg/day (0.73 g/lb) is the threshold for maximizing resistance-training-induced muscle gains, with the 95% confidence interval extending to 2.2 g/kg. The International Society of Sports Nutrition (ISSN) recommends 1.4–2.0 g/kg for exercising individuals.
During a calorie deficit, protein needs increase. Helms et al. (2014) recommend 2.3–3.1 g/kg of lean body mass for resistance-trained athletes during a cut. A 2016 study by Longland et al. showed that participants eating 2.4 g/kg of protein in a 40% energy deficit actually gained lean mass while losing more fat than a lower-protein group. This calculator sets cutting protein at 2.4 g/kg of body weight (or 2.6 g/kg of lean body mass if body fat is provided).
Setting Your Fat Intake
Dietary fat is essential for hormone production — particularly testosterone — vitamin absorption, and cell membrane integrity. A 2022 meta-analysis by Whittaker and Harris found that diets below 20% of calories from fat produced statistically significant reductions in testosterone levels. This calculator sets fat at 25% of your goal calories, with a floor of 0.5 g/kg to protect hormonal health even at low calorie intakes.
Carbs: Fuel for Training
Carbohydrates are your body's primary fuel source for high-intensity exercise. Glycogen stored in your muscles powers sets in the 6–15 rep range — the range where most muscle growth happens. After protein and fat are set, the remaining calories go to carbohydrates. During a bulk, carbs will be highest, fueling harder training sessions. During a cut, carbs get compressed, but your protein and fat targets protect muscle and hormones while carbs flex down to fit your calorie budget.
How to Use Your Macro Targets
Treat these numbers as a starting point, not a rigid prescription. Track your food intake for 2–3 weeks using a food scale and an app. If your weight is trending the way you want and your training performance is good, your targets are dialed in. If not, adjust by 100–200 calories (primarily from carbs or fat) and re-evaluate. Prioritize hitting your protein target daily — it has the largest impact on body composition.
Pair your nutrition with a structured strength tracking and recovery monitoring approach. Nutrition tells you how much to eat. Your training log tells you if you are getting stronger. And recovery tracking tells you if your body is keeping up. Together, they give you the complete picture.
Track Your Training Alongside Your Nutrition
Slate logs your workouts in seconds, tracks every PR automatically, and monitors muscle recovery between sessions. Pair your macro targets with real training data to see what fuels your best performance.
Download Free for iOSFrequently Asked Questions
Macros (macronutrients) are the three main nutrients your body needs in large quantities: protein, fat, and carbohydrates. Each plays a different role — protein builds and repairs muscle tissue, fat supports hormones and cell function, and carbohydrates fuel high-intensity activity. Tracking your macros means hitting specific gram targets for each nutrient, not just total calories.
This calculator estimates your Total Daily Energy Expenditure (TDEE) using the Mifflin-St Jeor equation (or Katch-McArdle if you enter your body fat percentage), then adjusts calories for your goal. Protein is set based on peer-reviewed research — higher during a cut to preserve muscle, moderate during maintenance. Fat is set at 25% of total calories with a minimum floor for hormonal health. Carbohydrates fill the remaining calories.
Research consistently shows that 1.6 to 2.4 grams of protein per kilogram of body weight (0.7 to 1.1 g/lb) is optimal for most lifters. The exact amount depends on your goal: cutting requires more protein (2.0–2.7 g/kg) to preserve muscle in a deficit, while maintenance and bulking require less (1.6–2.0 g/kg). A 2018 meta-analysis by Morton et al. found 1.6 g/kg as the threshold for maximizing muscle gains, with diminishing returns above 2.2 g/kg.
Dietary fat is essential for hormone production, brain function, and nutrient absorption. Research suggests a minimum of 15–20% of total calories from fat to maintain healthy testosterone levels. This calculator sets fat at 25% of total calories, which balances hormonal health with enough room for adequate protein and carbs. A 2022 meta-analysis by Whittaker and Harris found that low-fat diets (below 20% of calories) significantly reduced testosterone levels.
Tracking macros is more effective than tracking calories alone, especially for body composition goals. Two people eating the same number of calories can get very different results depending on their macro split. Eating too little protein leads to muscle loss during a cut and slower muscle gain during a bulk. If tracking all three macros feels overwhelming, prioritize hitting your protein target and staying within your calorie goal — those two factors account for most of the results.
For fat loss, eat at a 15–25% calorie deficit with protein set high at 2.0–2.7 g/kg of body weight (0.9–1.2 g/lb). This preserves muscle mass while you lose fat. Fat should be around 20–30% of total calories, and carbohydrates fill the rest. A 2016 study by Longland et al. found that participants eating 2.4 g/kg of protein during an aggressive deficit actually gained lean mass while losing significantly more fat than the lower-protein group.
For muscle building, eat at a 10–20% calorie surplus with protein at 1.6–2.2 g/kg (0.7–1.0 g/lb). The surplus provides extra energy for muscle protein synthesis. Fat at 25–35% of calories supports hormonal health, and carbohydrates should make up the largest share of your remaining calories to fuel training performance. The ISSN recommends 1.4–2.0 g/kg of protein for exercising individuals, with higher intakes for serious lifters.
Body recomposition (recomp) means losing fat and building muscle simultaneously. It works best for beginners, people returning to training after a break, and those with higher body fat. Recomp requires eating at or slightly below maintenance calories with high protein (2.0–2.4 g/kg) and consistent resistance training. Progress is slower than dedicated cutting or bulking phases but produces a leaner physique without the need to gain weight first.
Body fat percentage is optional but improves accuracy in two ways. First, it lets the calculator use the Katch-McArdle equation for BMR, which accounts for lean body mass and is more accurate for very muscular or very overweight individuals. Second, it adjusts protein targets during a cut to use lean body mass instead of total weight, which prevents unnecessarily high protein targets for people with higher body fat. If you do not know your exact body fat percentage, the calculator works well without it.