How the split is chosen
The calculator sets the three macros in a fixed order, because each has a different job.
1. Protein first, from your body weight
Protein needs scale with your body, so the calculator sets protein in grams per kilogram (or pound) of body weight. Sports nutrition research supports about 1.4 to 2.0 g per kg (0.64 to 0.91 g per lb) for people who exercise, with more on the higher side while losing fat to help keep muscle.
2. Fat as a share of calories
Fat is set at 25 to 30% of your calories. That sits inside the 20 to 35% range the National Academies set for adults (their Acceptable Macronutrient Distribution Range), and leaves room for carbs.
3. Carbs fill the rest
Carbs get whatever calories are left. Protein and carbs have about 4 kcal per gram and fat about 9 kcal per gram, so the grams follow from the calories. The same National Academies ranges put carbs at 45 to 65% and protein at 10 to 35% of calories for adults.
The goal presets
| Goal | Calories | Protein | Fat | Carbs |
|---|---|---|---|---|
| Fat loss | About 500 kcal below maintenance | 1.8 g per kg (0.8 g per lb) | 30% of calories | The rest |
| Maintenance | About maintenance | 1.4 g per kg (0.65 g per lb) | 30% of calories | The rest |
| Muscle gain | About 250 kcal above maintenance | 1.8 g per kg (0.8 g per lb) | 25% of calories | The rest |
Fat loss keeps protein higher because you're eating less overall. Muscle gain trims fat a little so more of the extra calories go to carbs, which fuel training.
If you have a lot of weight to lose, per-kilogram protein targets based on your current weight can come out very high. Use your goal weight in the weight box instead.
Worked example: fat loss, in pounds
A 35-year-old woman, 5 ft 5 in and 170 lb (77.1 kg), moderately active, has a maintenance of about 2,270 kcal. Her fat-loss target is about 1,770 kcal.
- Protein: 77.1 kg × 1.8 = 139 g (556 kcal, 31% of calories)
- Fat: 1,770 × 30% ÷ 9 = 59 g (531 kcal, 30%)
- Carbs: (1,770 − 556 − 531) ÷ 4 = 171 g (39%)
Spread over 3 meals, that's about 46 g protein, 57 g carbs and 20 g fat per meal. Her carbs land under 45% of calories, which is normal on a higher-protein fat-loss plan.
Worked example: muscle gain, in kilograms
A 28-year-old man, 180 cm and 85 kg, lightly active, has a maintenance of 2,530 kcal. His muscle-gain target is about 2,780 kcal.
- Protein: 85 kg × 1.8 = 153 g (612 kcal, 22%)
- Fat: 2,780 × 25% ÷ 9 = 77 g (693 kcal, 25%)
- Carbs: (2,780 − 612 − 693) ÷ 4 = 369 g (53%)
If he chose maintenance instead, he'd get 119 g protein, 84 g fat and 325 g carbs at 2,530 kcal.
Macros for women
The rules don't change by sex. Women usually get a lower calorie target, so the grams of carbs and fat come out lower, while protein still follows body weight. The fat-loss example above is a typical result for a moderately active woman.
Hitting your numbers day to day
Aim to land within about 10% of each target on most days. Protein is the one worth watching most, because it's the easiest to come up short on. Fiber matters too: the Dietary Guidelines for Americans use about 14 g of fiber per 1,000 kcal as a goal.
In CaloriePix, every meal you log shows protein, carbs and fat, plus fiber, sugar and sodium. The app sets daily calorie and macro targets from your goal weight and pace, and with the subscription you can set your own targets in Settings › Daily targets.
FAQ
What macros should I eat to lose weight?
A common starting point is about 1.6 to 2.2 g of protein per kg (0.7 to 1.0 g per lb), 25 to 30% of calories from fat, and the rest from carbs, all inside a modest calorie deficit. The calorie deficit drives weight loss, and enough protein together with strength training helps you keep muscle while you lose.
Is there a free macro calculator for women?
Yes, this one. Choose Female and enter your details. The calculator uses the female form of the Mifflin-St Jeor equation for your calories, then applies the same protein, fat and carb rules.
Can I use this for keto or low-carb?
Choose "Set my own split" and enter your own percentages. Keto plans typically keep carbs very low and fat high. If you have diabetes or take blood-sugar medication, talk to your doctor before cutting carbs sharply.
Should protein be based on my current or goal weight?
If you're close to a healthy weight, use your current weight. If you have a lot to lose, use your goal weight so the protein target stays realistic.
How accurate is a macro calculator?
It turns a calorie estimate into grams with simple rules, so it's only as good as the calorie number underneath. Use it as a starting point and adjust based on your weight trend, energy and training.
Do macros matter if I hit my calories?
Calories decide whether you gain or lose weight. Macros affect what that weight is: enough protein and some strength training help you keep muscle while you lose fat.
Sources
- Institute of Medicine (National Academies). Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids. 2005. doi:10.17226/10490. Summary table of Acceptable Macronutrient Distribution Ranges: National Academies (PDF)
- Jäger R, Kerksick CM, Campbell BI, et al. International Society of Sports Nutrition Position Stand: protein and exercise. Journal of the International Society of Sports Nutrition. 2017;14:20. doi:10.1186/s12970-017-0177-8
- 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. British Journal of Sports Medicine. 2018;52(6):376–384. doi:10.1136/bjsports-2017-097608
- U.S. Department of Agriculture and U.S. Department of Health and Human Services. Dietary Guidelines for Americans, 2020–2025, Appendix 1: Daily Nutritional Goals (fiber: 14 g per 1,000 kcal).
- Mifflin MD, St Jeor ST, Hill LA, et al. A new predictive equation for resting energy expenditure in healthy individuals. American Journal of Clinical Nutrition. 1990;51(2):241–247. doi:10.1093/ajcn/51.2.241
Snap a meal and see protein, carbs and fat for each item, plus fiber, sugar and sodium.
