Macro Calculator
Macros, protein, carbohydrate and fat, are the three nutrients that make up your calories. Getting the split right, especially protein, decides whether the weight you lose is fat or muscle, and whether a bulk builds muscle or just fat.
How the split is set
Protein comes first, set by body weight at a level shown to protect and build muscle: about 1.6 g/kg to maintain, up to roughly 1.9–2.0 g/kg when losing fat or building.45 Fat is set at 25–30% of calories to support hormones. Carbohydrate fills whatever calories remain, fuelling your training and daily energy.
Older adults (65+) are nudged to a higher protein floor, because ageing muscle needs more protein to respond to the same stimulus.6
Do the ratios really matter?
Less than the internet claims, with one exception. For fat loss, total calories decide how much you lose and protein decides how much of it is fat versus muscle. The exact carb-to-fat split is mostly personal preference, eat the ratio you can stick to.
Common questions
Should I eat low-carb or low-fat?
Whichever you prefer and can sustain. Once protein and total calories are set, the carb-to-fat split barely affects fat loss. Pick the one that keeps you full and fits your food.
Do I need to hit my macros exactly?
Protein is worth hitting closely; it protects muscle. Carbs and fat can swing 10–20 g day to day with no problem, as long as your weekly calories are on target.
Why is my protein target based on a lower weight?
If you carry a lot of excess fat, the calculator uses a leaner reference weight so the protein number stays sensible. You don't need to feed your fat mass protein.
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- Morton RW, Murphy KT, McKellar SR, 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. Br J Sports Med. 2018;52(6):376-384. Source
- Helms ER, Zinn C, Rowlands DS, Brown SR. A systematic review of dietary protein during caloric restriction in resistance trained lean athletes. Int J Sport Nutr Exerc Metab. 2014;24(2):127-138. Source
- Bauer J, Biolo G, Cederholm T, et al. Evidence-based recommendations for optimal dietary protein intake in older people: a position paper from the PROT-AGE Study Group. J Am Med Dir Assoc. 2013;14(8):542-559. Source
- Mifflin MD, St Jeor ST, Hill LA, et al. A new predictive equation for resting energy expenditure in healthy individuals. Am J Clin Nutr. 1990;51(2):241-247. Source
This calculator is general information, not medical advice, and its results are estimates for healthy adults. Speak to a doctor or registered dietitian before making significant changes, especially if you are pregnant or breastfeeding, under 18, or manage a medical condition.
