Macro Calculator
Free macro calculator using Mifflin-St Jeor for BMR, TDEE, and daily protein, carb, and fat targets for fat loss, maintenance, or muscle gain on any challenge.
Macro Calculator
Units
About you
Used by the Mifflin-St Jeor formula only.
Activity level
Goal
Diet preference
Daily macros
Estimates only. Macro needs vary with body composition, NEAT, sleep, training history, and medical conditions. Talk to a registered dietitian or your doctor before changing your diet, especially if you are pregnant, nursing, under 18, or have a metabolic condition.
How macros work: protein, carbs, and fat
Macros are the three nutrients your body burns for energy: protein, carbs, and fat. Each one does a different job. Protein (4 cal/g) repairs and builds muscle, especially when you are training or in a calorie deficit. Carbs (4 cal/g) fuel your workouts and brain, and they are the easiest energy source for high-intensity sessions. Fat (9 cal/g) supports hormone production, vitamin absorption, and keeps you full between meals.
The Institute of Medicine sets an Acceptable Macronutrient Distribution Range (AMDR) of 10 to 35% of calories from protein, 45 to 65% from carbs, and 20 to 35% from fat. Most balanced and high-protein splits sit comfortably inside that window. Low-carb and keto splits step outside the AMDR on purpose, and they work well for some people, but they are not the only valid option.
How to calculate your macros
The math runs in three steps. First, your basal metabolic rate (BMR) is what your body burns at rest. We calculate it with the Mifflin-St Jeor equation (Mifflin and St Jeor, 1990), which lands within about 10% of indirect calorimetry and beats the older Harris-Benedict formula for accuracy. Second, your total daily energy expenditure (TDEE) is your BMR multiplied by an activity factor: 1.2 for sedentary, 1.375 for lightly active, 1.55 for moderate, 1.725 for very active, and 1.9 for extra active.
Third, your daily calorie target adjusts TDEE based on your goal: 20% below for fat loss, match for maintenance, or 10% above for lean muscle gain. From there, the diet preference splits the calorie total into grams. Balanced (30 / 40 / 30) is the default for general health. High-protein (40 / 30 / 30) is the most-recommended split for fat loss with muscle preservation. Low-carb (35 / 25 / 40) and keto (25 / 5 / 70) are options if you have done well on those approaches before.
Macros for the 75-day challenge diet
Most 75-day challenges (75 Hard, created by Andy Frisella, plus our own 75 Tough and 75 Soft variants) ask you to follow a diet of your choice with no cheat meals. The structure cares more about adherence than which specific diet you pick, so the macro split that works best is the one you can actually run for 75 days. For most people training twice a day, that is the high-protein split at a 20% deficit. Protein protects muscle while you cut, carbs keep both daily workouts fueled, and fat fills in the rest.
If you are running 75 Tough or 75 Soft, the same logic applies but the deficit can be smaller (10 to 15%) since the workout demand is lower. Run this calculator alongside the calorie deficit calculator to compare the two views, and use the 75-day challenge calculator to map your start and end dates. Reset75 handles the daily checklist part once your numbers are dialed in.
Tracking your macros consistently
The biggest win for macro tracking is a kitchen scale. Cup measurements are off by 20 to 50% on most foods, and once your daily target sits under 1,800 calories, that error is enough to wipe out a deficit. Weigh protein and carbs raw when you can, log everything in MyFitnessPal or Cronometer, and use this calculator's "Copy summary" button to paste your targets in once.
Three mistakes show up over and over. Under-tracking on weekends: a clean Monday-to-Friday paired with two unmeasured weekend days will often erase the entire week. Dropping protein when you cut calories: protein is the macro you protect, even if it means less fat or fewer carbs. Ignoring training-day vs rest-day differences: most people do better with slightly more carbs on lift days and slightly more fat on rest days, even when the weekly average is the same.
Recalculate every 10 to 15 lb of weight change, every 2 to 4 weeks of plateau, or whenever your training load shifts noticeably. Your TDEE is a moving target, and the macros you started a 75-day challenge with on day 1 are almost never the right macros on day 50.
Frequently Asked Questions
Common questions about macro calculator
What is a macro calculator?
A macro calculator estimates your daily intake of the three macronutrients (protein, carbs, and fat) based on your body, activity level, and goal. This one starts with the Mifflin-St Jeor equation to find your BMR, multiplies by an activity factor for your TDEE, then splits the result into grams of each macro.
How do I calculate my macros?
Enter your age, sex, height, weight, and activity level, then pick a goal (lose fat, maintain, or build muscle) and a diet preference (balanced, high-protein, low-carb, or keto). The calculator handles the math: BMR, TDEE, daily calorie target, and grams of protein, carbs, and fat. Pair it with the calorie deficit calculator if you want a different way to look at the deficit math.
What are good macros for fat loss?
A common evidence-based split is 40% protein, 30% carbs, 30% fat at roughly 80% of your TDEE (a 20% deficit). The high protein anchor (about 0.7 to 1.0 g per pound of body weight) helps preserve muscle while you are in a deficit. Pick the High-protein chip in this calculator to use that split.
How accurate is a macro calculator?
Macro calculators are estimates. The Mifflin-St Jeor equation lands within about 10% of indirect calorimetry for most adults, but real-world calorie burn shifts with body composition, NEAT, sleep, and stress. Use the numbers as a starting point, then adjust every 2 to 4 weeks based on actual progress.
Should I count calories or macros on a 75-day challenge?
Macros, ideally. A 75-day challenge usually pairs a calorie deficit with two daily workouts, and high protein protects the muscle you are building. Tracking macros instead of just calories also keeps fat and carbs in a sustainable range so you have energy for both workouts.
Do macros change for muscle gain vs fat loss?
The split stays similar (high-protein works in both directions), but the calorie total changes. For fat loss, eat about 20% below TDEE. For lean muscle gain, eat about 10% above TDEE, which is roughly a 250 to 500 cal surplus. Protein in grams stays anchored to your body weight either way.
What is the best protein intake for a 75-day challenge?
Aim for 0.7 to 1.0 g of protein per pound of body weight per day. Higher protein intake during a calorie deficit preserves muscle and improves satiety. The high-protein and balanced splits in this calculator both hit that range for most people.
How often should I recalculate my macros?
Every 2 to 4 weeks, or whenever your weight changes by 10 to 15 lb, your activity level shifts, or progress stalls for more than 2 to 3 weeks. As your body gets smaller, your TDEE drops, so the target you started with on day 1 of a 75-day challenge will not be the right target on day 50.