Macro Calculator (Body-Weight g/kg)
Bodyweight-based (g/kg) macro calculator. Protein, carbs, fat targets from TDEE + body weight + goal (cut, maintain, bulk). Evidence-based ratios per ISSN + Helms 2014.
Macro Calculator
How to use the macro calculator
Enter weight + TDEE
Body weight in kg (use the RMR calculator first to get your TDEE if you don't know it). TDEE = Total Daily Energy Expenditure ≈ RMR × activity multiplier. Both numbers anchor the macro calculation.
Choose goal
Maintain: TDEE calories. Cut: TDEE − 300 or − 500 kcal. Bulk: TDEE + 250 or + 500 kcal. These are fixed steps, not predictions: how fast weight actually changes slows as your body adapts, so weigh yourself over a few weeks and adjust. Helms et al. suggest a deficit that loses about 0.5–1% of body weight a week when the aim is to keep muscle.
Set protein per kg
Grams per kg of body weight. The ISSN position stand (Jäger et al. 2017) gives 1.4–2.0 g/kg/day for most exercising people, and 2.3–3.1 g/kg/day for resistance-trained people trying to keep lean mass while eating less. A meta-analysis of 49 trials (Morton et al. 2018) found gains in fat-free mass levelled off at about 1.6 g/kg/day, with a confidence interval up to 2.2. The default of 2.0 sits inside both ranges.
Set fat percentage
A share of the calorie target. Helms et al. (2014) recommend 15–30% of calories from fat during contest preparation; the default is 25%. The box accepts 15–50% so you can model higher-fat diets too.
Carbs fill the remaining calories
Carbs aren't "essential" macronutrient-wise (the body can survive without dietary carbs) but they're the cheapest energy source + critical for high-intensity training. Carb intake = (total calories − protein kcal − fat kcal) / 4. If protein and fat already use up the target, carbs show 0 g and the page says the target cannot be met at those settings.
Macros — protein matters most, then total calories, then ratio
This calculator works in grams per kilogram of body weight, the sports-nutrition method: protein is set from your weight, fat as a share of the calorie target, and carbohydrate takes whatever is left. For context, the Institute of Medicine's acceptable range for protein is 10% to 35% of calories, and the RDA of 0.8 g/kg/day is a minimum to prevent deficiency, not an amount meant for training athletes — the ISSN position stand says as much. Prefer to plan your day as a percentage split of a computed calorie budget? Use our macros calculator, the calorie-split planner.
Total calories = 4 × protein grams + 4 × carbohydrate grams + 9 × fat grams. On the defaults — 70 kg, 2,500 kcal, 2.0 g/kg and 25% fat — that is 140 g of protein (560 kcal), 69 g of fat (625 kcal) and 329 g of carbohydrate (1,315 kcal): a 22 / 53 / 25 split.
Where the protein numbers come from
The International Society of Sports Nutrition's position stand (Jäger et al. 2017) recommends 1.4–2.0 g/kg/day for most exercising people, and 2.3–3.1 g/kg/day for resistance-trained people trying to keep lean mass while eating less. Morton et al.'s 2018 meta-analysis of 49 trials found that added protein stopped increasing gains in fat-free mass at about 1.6 g/kg/day, with a 95% confidence interval up to 2.2, and suggested about 2.2 for anyone trying to maximise gains. Helms et al.'s 2014 review for natural bodybuilders preparing for a contest put protein at 2.3–3.1 g per kg of lean mass, fat at 15–30% of calories and carbohydrate as the remainder, with a deficit that loses about 0.5–1% of body weight a week.
Set protein from body weight first, then fit fat and carbohydrate into the calories that remain.
Why the goal steps are only steps
The cut and bulk presets move the target by a fixed number of calories. They are not a forecast of weekly change: weight loss slows as the body adapts to eating less, so treat the first few weeks as a test, weigh yourself on the same day each week, and adjust. If protein and fat together already exceed the target, the page shows carbohydrate at 0 g and says so rather than printing a negative number.
4, 4 and 9 kcal per gram, and protein per kilogram of body weight
1g protein = 4 kcal, 1g carb = 4 kcal, 1g fat = 9 kcal. Memorise these.
The ISSN position stand (2017): 1.4–2.0 g/kg/day of protein for most exercising people.
Morton et al. 2018: gains in fat-free mass levelled off at about 1.6 g/kg/day (95% CI 1.03–2.20).
Helms et al. 2014: 2.3–3.1 g per kg of lean mass during contest preparation, not of body weight.
The RDA of 0.8 g/kg/day is a deficiency floor, not a training target.
On the defaults, 2.0 g/kg at 70 kg is 140 g of protein, 22% of 2,500 kcal.
IIFYM (If It Fits Your Macros): track macros + total calories. Food source matters less for composition than people think.
Helms et al. suggest a deficit that loses 0.5–1% of body weight a week when keeping muscle matters.
The cut and bulk presets are fixed calorie steps; how fast weight changes slows as the body adapts.
Diet adherence > optimal macros. Pick ratios you can sustain for months, not a perfect plan you abandon in 2 weeks.
Frequently asked questions
For most exercising people, 1.4–2.0 g per kg of body weight a day (ISSN position stand, 2017). Morton et al.'s 2018 meta-analysis found extra protein stopped adding fat-free mass at about 1.6 g/kg/day (95% CI 1.03–2.20). When eating less while resistance training, the ISSN gives 2.3–3.1 g/kg/day to help keep lean mass. The RDA of 0.8 g/kg/day is a deficiency floor, not a training target.
This calculator does not settle that question. It meets a protein amount within a calorie target and then splits the rest between fat and carbohydrate as you choose; set fat high for a very-low-carbohydrate plan or low for a high-carbohydrate one. If you have diabetes or another medical condition, agree major diet changes with your doctor.
Calories drive weight change; protein, set high enough, helps keep or build muscle while that happens. The split between fat and carbohydrate matters less for body composition once those two are right, so choose one you can keep eating.
Use a food-tracking app with a nutrient database and weigh food on a kitchen scale rather than estimating portions. Track for a couple of weeks to establish a baseline, then adjust.
No — weekly averaging is fine for most people. Going under protein one day + over the next is usually neutral. Total weekly calorie balance drives weight outcomes more than perfect daily macros. Some athletes use targeted refeeds (high-carb days) within a weekly deficit framework.
The ISSN position stand discusses timing and dose per meal as well as the daily total; for most people the daily protein total, met consistently, comes first. Spread protein across the day in a way you can keep up.
No. The calculator fixes protein by body weight and fat by percentage, and lets carbohydrate take what remains, so the resulting split changes with your weight, calorie target and settings. Traditional cuisines and diets differ widely in their mix; what the evidence above supports is meeting a protein amount within your calories, not any one ratio.
No. All inputs stay in your browser.
Track for at least two weeks before changing anything: water and stored carbohydrate move the scale day to day. If weight is stable on cut macros, your TDEE was probably overestimated, so lower the target and retest; if it falls faster than you want, raise it. Helms et al. suggest losing about 0.5–1% of body weight a week when keeping muscle matters.
The ISSN position stand on protein and exercise (Jäger et al. 2017, J Int Soc Sports Nutr), Morton et al.'s 2018 meta-analysis in the British Journal of Sports Medicine, and Helms et al.'s 2014 review of contest preparation (J Int Soc Sports Nutr). All three are open access and listed under Method & sources.
Method & sources
How it computes
Target = TDEE + goal step (-500, -300, 0, +250, +500 kcal). Protein g = g/kg x body weight; fat g = target x fat% / 9; carbs g = (target - protein kcal - fat kcal) / 4, clamped at 0 with the split then taken over calories actually eaten; percentages by largest remainder. Atwater 4/4/9. RecaMacros, tested.
What this tool implements
- Misattribution corrected: the page credited 1.6-2.2 g/kg/day of protein to Helms et al. 2014. Helms's contest-preparation range is 2.3-3.1 g per kg of LEAN mass with fat 15-30% of calories and 0.5-1% body-weight loss a week; 1.62 g/kg/day (95% CI 1.03-2.20) is Morton et al.'s 2018 plateau in 49 RCTs; ISSN gives 1.4-2.0 (2.3-3.1 when hypocaloric). RDA 0.8 g/kg and AMDR 10-35% per the ISSN text.
- The '0.5 g/kg fat minimum' the code comment promised was never enforced and no source read supports it, so the claim is removed rather than enforced. The kg-per-week figures attached to each goal preset are removed: the presets are fixed calorie steps, not forecasts. The arithmetic moved into a tested kernel.
- Removed as unsourced: '2.0-2.4 g/kg during cuts (Helms 2014, Phillips 2016)', '2.4-2.8 for physique competitors', ASEAN 55-65% carbohydrate diets, visual estimation errors of 20-40%, keto claims, the 'anabolic window' figure, and 3-5 g/kg carbohydrate.
Sources
- 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. https://doi.org/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. Br J Sports Med. 2018;52:376-384. https://doi.org/10.1136/bjsports-2017-097608
- Helms ER, Aragon AA, Fitschen PJ. Evidence-based recommendations for natural bodybuilding contest preparation: nutrition and supplementation. J Int Soc Sports Nutr. 2014;11:20. https://doi.org/10.1186/1550-2783-11-20
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