Free tool · Nutrition

Macro calculator: protein, carbs and fat

Short answer

The Institute of Medicine's acceptable ranges for adults are 45–65% of calories from carbohydrate, 20–35% from fat and 10–35% from protein. On 2,000 kcal a day, that is 225–325 g of carbohydrate, 44–78 g of fat and 50–175 g of protein. Pick a split inside those ranges and the calculator converts it to grams.

Last reviewed 26 October 20262 published sourcesNot medical advice

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Macro calculator

Enter your daily calories. Add your own split to convert it to grams.

Enter your daily calories to see the reference ranges in grams.

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The reference ranges

The Institute of Medicine set acceptable macronutrient distribution ranges (AMDRs) for adults: 45–65% of energy from carbohydrate, 20–35% from fat and 10–35% from protein (Institute of Medicine, 2005 (macronutrients)). Intakes inside those ranges are associated with a lower risk of chronic disease while still providing enough essential nutrients.

The calculator rejects a split outside those ranges or one that does not add up to 100%, and shows the calories your rounded grams actually supply.

Macronutrient ranges in grams per day
Calories	Carbohydrate 45–65%	Fat 20–35%	Protein 10–35%
1,600 kcal	180–260 g	36–62 g	40–140 g
1,800 kcal	203–293 g	40–70 g	45–158 g
2,000 kcal	225–325 g	44–78 g	50–175 g
2,200 kcal	248–358 g	49–86 g	55–193 g
2,500 kcal	281–406 g	56–97 g	63–219 g
2,800 kcal	315–455 g	62–109 g	70–245 g
3,200 kcal	360–520 g	71–124 g	80–280 g

4 kcal per gram of carbohydrate and protein, 9 kcal per gram of fat. Rounded to the nearest gram.

Setting protein first

For people doing resistance training, a meta-analysis found gains in fat-free mass levelled off at about 1.6 g of protein per kg of body weight per day (Morton et al., 2018). That is often a better anchor than a percentage, because it scales with your body rather than your calories. The protein calculator works it out for you.

Need a calorie target first? Start with the TDEE calculator.

Hit your macros without a spreadsheet

Snap, say or type a meal in Reps and it breaks it into calories, protein, carbs and fat, tracked against your day next to your training.

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Common questions

How do I calculate my macros?

Start from a daily calorie target, choose what share comes from each macronutrient, then convert: carbohydrate and protein provide 4 kcal per gram and fat 9 kcal per gram. For example, 30% protein on 2,000 kcal is 600 kcal, or 150 g.

What is a good macro split?

Any split inside the Institute of Medicine's acceptable macronutrient distribution ranges (45–65% carbohydrate, 20–35% fat, 10–35% protein) is consistent with a healthy adult diet. If you lift and want to build muscle, set protein from body weight first (about 1.6 g per kg a day) and fill the rest with carbohydrate and fat.

Do I count alcohol and fibre?

This calculator splits calories between the three main macronutrients only. Alcohol supplies energy (about 7 kcal per gram) that is not part of any macro target, and fibre is counted inside carbohydrate here.

Sources

Figures on this page were checked against these publications on 26 October 2026.

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. doi.org/10.17226/10490
Morton RW, Murphy KT, McKellar SR, Schoenfeld BJ, Henselmans M, Helms E, et al. A systematic review, meta-analysis and meta-regression of the effect of protein supplementation on resistance training-induced gains in muscle mass and strength in healthy adults. British Journal of Sports Medicine. 2018;52(6):376–384. doi.org/10.1136/bjsports-2017-097608

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