Macro Calculator

How many grams of each macro do I need?

Macronutrients ("macros") are the three nutrients that supply calories: protein, carbohydrate and fat. A macro calculator answers a narrower question than a calorie counter. Once you know roughly how much energy you need, it turns that into grams of each nutrient you can match against food labels. If you only want the calorie number, or want to compare weight-change rates, the daily calorie calculator is the better starting point. This page takes that same estimate and breaks it into protein, carbs and fat.

The macros you get depend on two choices. Your goal sets the total calories, and your diet split sets how those calories divide. The same 2,000 kcal could be 150 g of protein on a balanced split or 100 g on keto. Neither is "correct" for everyone. The best split is one you can sustain, that covers your protein needs, and that fits how you train.

How the macros are calculated

The calculator works in five steps, using the same equations as our other health calculators so the numbers line up:

1. Resting energy. Your basal metabolic rate comes from the Mifflin-St Jeor equation: 10 × weight (kg) + 6.25 × height (cm) − 5 × age, plus 5 for men or minus 161 for women. The BMR calculator explains this equation in more depth.
2. Activity. BMR is multiplied by an activity factor from 1.2 (sedentary) to 1.9 (very active) to estimate maintenance calories.
3. Goal. "Lose" subtracts 500 kcal a day and "gain" adds 500. That's roughly 1 lb (0.45 kg) a week at first, though real-world loss slows as your body adapts.
4. Floor. A weight-loss target is never set below 1,200 kcal for women or 1,500 kcal for men. These are commonly used minimums for dieting without medical supervision. If your estimated maintenance is already below the floor, the calculator keeps you at maintenance and shows a warning instead of prescribing a deficit.
5. Split. Calories are divided by your chosen percentages, then converted to grams with the standard Atwater factors: 4 kcal per gram of protein, 4 per gram of carbohydrate and 9 per gram of fat.

Each macro's calories are rounded to whole numbers that add back up to your exact target. Grams are then rounded to the nearest gram, so grams × 4/4/9 may differ from the total by a few kcal. Alcohol (7 kcal/g) isn't part of any split. If you drink, those calories come out of the same daily budget.

Worked example

Take a 35-year-old woman who weighs 68 kg (about 150 lb), is 165 cm (5 ft 5 in) tall, exercises 3–5 days a week and wants to lose weight on the balanced split:

• BMR = 10 × 68 + 6.25 × 165 − 5 × 35 − 161 = 1,375 kcal
• Maintenance = 1,375 × 1.55 = 2,131 kcal
• Target = 2,131 − 500 = 1,631 kcal (above the 1,200 floor, so no adjustment)
• Protein: 30% = 489 kcal ÷ 4 = 122 g (1.79 g/kg)
• Carbs: 40% = 653 kcal ÷ 4 = 163 g
• Fat: 30% = 489 kcal ÷ 9 = 54 g
• Over 3 meals: about 544 kcal, 41 g protein, 54 g carbs and 18 g fat each

With US inputs (150 lb, 5 ft 5 in) the result can differ by a few kcal, because 150 lb is 68.04 kg and 5 ft 5 in is 165.1 cm.

Macro splits by diet: grams at 1,500, 2,000 and 2,500 kcal

The table shows each preset's daily grams of protein / carbs / fat at three common calorie levels. It's calculated with the same code as the calculator, before any protein adjustment for body weight (see the next section).

Balanced (30/40/30) is a common fitness default. Its carbohydrate share is a little under the 45–65% range the US Dietary Reference Intakes set for adults, while protein (10–35%) and fat (20–35%) fall inside their ranges. High-protein (40/35/25) suits people in a deficit who lift weights and want to protect muscle. Low-carb (35/25/40) and keto (20/5/75) sit well outside the reference ranges for carbohydrate and fat. That doesn't make them unsafe for most healthy adults, but it's a reason to plan meals carefully for fiber and micronutrients. Keto at 5% of calories works out to roughly 19–31 g of carbohydrate a day at these calorie levels. Anyone taking diabetes medication should talk to their prescriber before cutting carbs this far, because doses may need changing.

Protein per kilogram: why the calculator adjusts it

Percentages alone can produce odd protein targets. Thirty percent of 2,600 kcal is about 195 g, which is close to 2.8 g/kg for an active 70 kg man. At the other end, the keto preset's 20% protein can fall below 1.2 g/kg for a heavier person in a deficit. So the calculator also checks grams per kilogram of body weight:

• The adult RDA is 0.8 g/kg a day. This is the floor for sedentary and lightly active settings.
• Position stands from the International Society of Sports Nutrition and the American College of Sports Medicine put active people at about 1.2–2.0 g/kg. The calculator uses 1.2 g/kg as the floor for moderate activity and above, and 2.0 g/kg as the ceiling for everyone.

If a preset lands outside that range, protein is moved to the nearest limit. The calories gained or freed go to carbs and fat in the preset's original proportion, so your total doesn't change. Custom splits are left exactly as you set them, but a note flags protein outside the range. For a dedicated protein target with more options, use the protein intake calculator. Grams per kilogram use total body weight. People with a lot of body fat may find a target based on lean mass more realistic, which you can estimate with the body fat calculator.

Hitting your numbers day to day

Treat the grams as a target range, not an exact quota. Within about 5–10 g of protein and carbs, and 5 g of fat, is close enough. Daily weight changes from water and food volume swamp anything smaller. Many people find it easiest to fix protein first (a palm-sized portion of meat, fish, tofu or Greek yogurt per meal), fill in carbs around training, and let fat take up the rest.

The per-meal split simply divides the day evenly. You can shift carbs toward the meal before or after a workout, or run a smaller snack plus three meals, as long as the daily totals land close. Re-run the calculator after every 4–5 kg (about 10 lb) of weight change, or if your training volume changes. Maintenance calories move with body size, and so do the protein limits.

After 2–4 weeks, compare the trend in your weight against the goal. If you're losing much faster or slower than about 0.5 kg (1 lb) a week, adjust calories by 100–200 a day rather than overhauling the split. The equations behind any calculator are population averages and can be off by 10% or more for an individual.

Sources

The formulas on this page come from the published research below. Last updated October 10, 2026. This calculator gives estimates for general information. It isn't medical advice, so check anything important with a qualified professional.

1. Mifflin MD, St Jeor ST, Hill LA, Scott BJ, Daugherty SA, Koh YO. A new predictive equation for resting energy expenditure in healthy individuals. Am J Clin Nutr. 1990;51(2):241–247.Used for: BMR, multiplied by an activity factor (1.2–1.9) for the calorie target the macros are split from
2. Institute of Medicine. Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids. Washington, DC: The National Academies Press; 2005.Used for: 0.8 g/kg protein RDA and acceptable macronutrient ranges (protein 10–35%, carbohydrate 45–65%, fat 20–35%)
3. Jäger R, Kerksick CM, Campbell BI, et al. International Society of Sports Nutrition Position Stand: protein and exercise. J Int Soc Sports Nutr. 2017;14:20.Used for: Upper protein limit of 2.0 g/kg/day for active people
4. Thomas DT, Erdman KA, Burke LM. American College of Sports Medicine Joint Position Statement: Nutrition and Athletic Performance. Med Sci Sports Exerc. 2016;48(3):543–568.Used for: 1.2–2.0 g/kg/day protein range for active people