Macro Calculator: Cutting and Bulking Modes

Most macro calculators online use the same lazy template: estimate calories, slap on a 40 percent carb / 30 percent protein / 30 percent fat split, and call it personalized. The split is not personalized to anything. It treats a 55 kg sedentary office worker and a 95 kg powerlifter as if they need the same protein-to-calorie ratio, which they obviously do not.

This calculator builds your numbers in the order the peer-reviewed literature actually supports. Calories first, anchored to your real body. Protein second, in absolute grams per kilogram of body weight from the 2018 Morton meta-analysis. Fat third, at a hormonal-health floor. Carbs last, as whatever calories are left to hit your goal. Every multiplier maps to a specific paper. The result is a target that scales with body size, training experience, and what you are actually trying to do.

How this calculator works

There are four steps under the hood, each grounded in a primary source.

• BMR (Mifflin-St Jeor): For men, BMR equals 10 times weight in kg plus 6.25 times height in cm minus 5 times age in years plus 5. For women, the constant at the end is minus 161 instead of plus 5. The Mifflin-St Jeor equation, published by Mifflin et al. 1990 in the American Journal of Clinical Nutrition, was validated against indirect calorimetry and predicts resting energy expenditure within roughly 10 percent for most healthy adults.
• TDEE (activity multiplier): Multiply BMR by an activity factor of 1.2 (sedentary), 1.375 (light), 1.55 (moderate), 1.725 (very active), or 1.9 (extra active). These multipliers come from the standard Harris-Benedict / Mifflin literature and the FAO/WHO physical activity level coefficients used in dietary guidelines. They are estimates, not measurements. Most adults find their real maintenance is within 200 kcal of the calculator's output after two weeks of weighed food and bodyweight tracking.
• Goal mode (the calorie target): Each of the five modes multiplies TDEE by a fixed factor. Aggressive cut uses 0.775 (a 22.5 percent deficit, the middle of the 20 to 25 percent band). Moderate cut uses 0.85 (15 percent, the middle of the 10 to 20 percent band). Maintain uses TDEE as is. Lean bulk uses 1.075 and standard bulk uses 1.15. The deficit ceiling comes from the Helms et al. 2014 review on protein during caloric restriction in the International Journal of Sport Nutrition and Exercise Metabolism; the rate the two cut modes target comes from Garthe et al. 2011; the surplus band comes from the Iraki et al. 2019 off-season review in Sports. One guardrail sits under all of it: the calculator will not hand back a target below your estimated BMR, because eating below resting expenditure indefinitely is not a plan, it is a symptom.
• Protein: The base comes from training experience. Sedentary adults start at 1.2 g/kg per the Phillips, Chevalier, and Leidy 2016 review. Beginners start at 1.6 g/kg, the lower bound of the Morton et al. 2018 meta-analysis in the British Journal of Sports Medicine. Intermediates start at 1.8 g/kg and advanced lifters at 2.0 g/kg. Then the goal mode shifts it: an aggressive cut adds 0.4 g/kg with a hard 1.8 g/kg floor and a moderate cut adds 0.2 g/kg with a 1.6 g/kg floor, both per the Helms et al. 2014 contest-prep paper, which scales protein up during cuts to preserve lean mass. A lean bulk adds 0.1 g/kg and a standard bulk subtracts 0.1 g/kg, staying inside the 1.6 to 2.2 g/kg off-season range in Iraki et al. 2019, because surplus calories already spare protein. Adults 65 and older get a 1.6 g/kg floor regardless of training status, per the PROT-AGE consensus (Bauer et al. 2013). Everything is capped at 2.4 g/kg, since Antonio et al. 2015 pushed resistance-trained adults to 3.4 g/kg with no harm but no added body-composition benefit.
• Fat: Defaults to 0.8 g/kg, a sensible hormonal-health target from Helms et al. 2014. The practical floor is 0.6 g/kg per the 2017 ISSN position stand on diets and body composition (Aragon et al.). Below about 20 percent of total calories from fat, sex hormones (testosterone in men, menstrual function in women) take a measurable hit.
• Carbs: Whatever calories remain after protein and fat, divided by 4 (since carbs supply 4 kcal per gram, the same as protein, while fat supplies 9). This is the most flexible macro because it is not bound by a hormonal-health minimum or a muscle-protein-synthesis ceiling.

If you only care about the protein number, our protein calculator gives you a focused, goal-aware target without computing fat and carbs. The two tools use compatible logic, so you will see the same protein number cross-referenced between them.

Should you bulk or cut first?

This is the question most people are actually asking when they open a macro calculator, and it is not a macro question. It is a body-fat question. Forbes showed in 2000 that the way any weight change splits between fat and lean tissue depends on how much fat you are carrying to begin with. The more body fat you have, the larger the share of a deficit that comes out of fat rather than muscle, and the larger the share of a surplus that gets stored as fat rather than added as lean mass. Body fat percentage, not the number on the scale, is the input to this decision.

The practical rule that falls out of that:

• Above roughly 20 percent body fat for men, or 30 percent for women: cut. A surplus at this level is heavily biased toward fat gain, and a deficit here costs you very little lean mass.
• Below roughly 12 percent for men, or 22 percent for women: bulk. Cutting from here starts taking real muscle with it. That is the dose-response Helms and colleagues traced in 2014, and it is why the steepest mode on this page stops at a 22.5 percent deficit rather than going further.
• In the band between those: either works. Pick by what you want to have finished six months from now. If you have never trained seriously, or you are coming back from a long layoff, you can add muscle and lose fat at the same time on maintenance calories, so start there.

If you do not know your body fat percentage, our body fat calculator estimates it from a tape measure using the validated US Navy circumference method. Get the number first, then set the goal below.

Using this page as a cutting calculator

Two of the five modes are cuts, and they differ in two settings: how far below maintenance the calorie target sits, and how hard the protein floor underneath it pushes back. Everything else, carbs, the per-meal split, and the projected weekly rate of loss, falls out of those two. Set the goal mode and the whole result card re-derives.

Moderate cut: 15 percent below maintenance

The moderate cut mode multiplies your maintenance calories by 0.85, sitting in the middle of the 10 to 20 percent band. Protein gets a 0.2 g/kg bump with a 1.6 g/kg floor, so an intermediate lifter moves from 1.8 to 2.0 g/kg. For the default 170 lb77 kg intermediate lifter on 2,693 kcal maintenance, that is 2,289 kcal, 154 g protein, 62 g fat, and 279 g carbs, which projects to about 0.48 percent of body weight lost per week.

That rate is the reason this is the default recommendation rather than the steeper option. Garthe et al. 2011 randomised 24 elite athletes to lose either 0.7 percent or 1.4 percent of body weight per week while strength training. The slow group gained 2.1 percent lean body mass over the block. The fast group gained none. Both lost fat. Only one of them came out the other side with more muscle than it started with. Who it suits: anyone with more than about eight weeks to spend, anyone still adding strength, and anyone who has crashed and rebounded before.

The aggressive cut calculator setting, and when it is defensible

The aggressive cut mode multiplies maintenance by 0.775, a 22.5 percent deficit, which is the middle of the 20 to 25 percent band that Helms et al. 2014 treats as the steep end of defensible. Protein gets a 0.4 g/kg bump with a hard 1.8 g/kg floor, which is the safety feature that matters most here: the leaner you get and the faster you go, the more of the lost weight comes from muscle, and protein is the only lever that reliably pushes back. The same default lifter lands at 2,087 kcal, 170 g protein, 62 g fat, and 213 g carbs, projecting to roughly 0.71 percent of body weight per week.

The result card keeps a standing caveat visible whenever this mode is active, and the calculator refuses to set a target below your estimated BMR no matter how the other inputs combine. Who it suits: people carrying enough body fat that a steep deficit still comes mostly out of fat (roughly above 20 percent for men or 30 percent for women), people with a hard deadline, and people running a short block of six to eight weeks rather than an open-ended diet. Who it does not suit: anyone already lean, anyone whose lifts are stalling, and anyone who has been dieting for months already. If that is you, drop back to moderate cut. We walk through the muscle-sparing side of this in our guide on how to lose fat without losing muscle.

Macros are only half of a cut. The training stimulus is what tells your body which tissue to keep, which is why a deficit with no resistance training reads as "lost weight" and a deficit with it reads as "got leaner." If you need the training half sorted too, we compared the options in the best workout apps for weight loss.

If you are maintaining instead

Maintenance is the most useful state to spend time in if you do not have an active body-composition goal. It is also where the calculator is most accurate, because there are no goal-driven adjustments to compound calorie estimation error. If your bodyweight has held steady for the last month, the calorie number you log over those four weeks is your real maintenance, regardless of what the calculator predicts. Use that.

Using this page as a bulking calculator

The other two modes are surpluses, and the split between them is the oldest argument in gaining: how fast is worth it. Iraki et al. 2019, a narrative review of off-season bodybuilding nutrition in Sports, recommends roughly 10 to 20 percent above maintenance, with the lower end (or less) for advanced lifters who add fat easily. The two bulk modes bracket that recommendation from below and from inside it.

Lean bulk: 7.5 percent above maintenance

Lean bulk multiplies maintenance by 1.075 and nudges protein up 0.1 g/kg, because a smaller calorie buffer leaves less room for error on the protein side. The default lifter lands at 2,895 kcal, 147 g protein, 62 g fat, and 438 g carbs, projecting to about 0.24 percent of body weight gained per week, or roughly 0.4 lb0.18 kg. Who it suits: intermediate and advanced lifters past the beginner window, anyone who is already near the top of their comfortable body fat range, and anyone who does not want to spend the next quarter cutting off what they just added.

Standard bulk: 15 percent above maintenance

Standard bulk multiplies maintenance by 1.15 and takes protein down 0.1 g/kg, since surplus calories already spare protein and the extra carbs buy more training volume. The default lifter lands at 3,097 kcal, 131 g protein, 62 g fat, and 504 g carbs, projecting to about 0.48 percent of body weight per week. Who it suits: beginners and returning lifters, people who genuinely struggle to eat enough, and anyone underweight enough that adding some fat alongside the muscle is a feature rather than a cost.

Neither mode is the "right" one in the abstract. The faster surplus does not reliably build more muscle inside a single block, it just gets you to the end of the block heavier, and some of that weight is fat you will pay to remove later. If you are still deciding which direction to run at all, our guide on bulking vs cutting works through the decision in more depth than the body-fat rule above.

Worked examples (for quick reference)

The first five rows are the same person in all five goal modes, so you can read the mode effect straight down the column. The last five change body, activity, age, and training experience. Every number below is what the calculator returns for those exact inputs.

Two things to read off that table. First, the protein column moves with the mode, not just with body size: the same lifter goes from 131 g on a standard bulk to 170 g on an aggressive cut, because the deeper the deficit the more of the defence against muscle loss has to come from protein. Second, the weekly-change column is the one to sanity-check against reality after three or four weeks. If the scale is not tracking it, the activity multiplier is the input that was wrong, not the math.

Per-meal distribution: the leucine threshold still matters

Total daily macros are the dominant variable. Distribution matters at the margins, mostly for protein. Schoenfeld and Aragon 2018 in the Journal of the International Society of Sports Nutrition recommend roughly 0.4 g of protein per kg of body weight at each of four meals, totaling about 1.6 g/kg/day at the floor. Each meal of that size contains roughly 2.5 g of leucine, which is the threshold dose for a full muscle-protein-synthesis response in adults under 65. We unpack the meal-level science in our companion piece on the leucine threshold.

Carbs and fat distribute more flexibly. Some people prefer the bulk of their carbs around training, which is reasonable but not required. Others tolerate larger fat-heavy meals at the start or end of the day. Total daily intake is what moves body composition. Distribution is what makes the day comfortable to eat. We covered the broader timing question in why the anabolic window is a myth.

Three myths the calculator deliberately ignores

Myth 1: low-carb is always better for fat loss

It is not. The 2017 ISSN diet review (Aragon et al.) summarized the head-to-head trials: when protein and calories are matched, low-carb and high-carb diets produce similar fat loss over weeks to months. Low-carb has an early water-weight advantage that fades. The factors that actually matter for cutting are total calorie deficit, protein intake high enough to preserve muscle, and adherence over the multi-month timescale that body composition responds on. We covered this in more depth in our piece on body recomposition.

Myth 2: you have to eat exactly 1 gram of protein per pound

This rule of thumb (about 2.2 g/kg) sits at the high end of the evidence-based range, not the middle. The Morton 2018 meta-analysis put the plateau at 1.62 g/kg, with the 95 percent confidence interval running from 1.03 to 2.20 g/kg. Eating 1 g/lb is not harmful (Antonio 2015 went to 3.4 g/kg with no adverse effects), but it is also not necessary for most lifters. The calculator scales protein by training experience inside the established window so beginners are not over-targeting and advanced lifters in a deficit are not under-targeting.

Myth 3: carbs at night make you fat

They do not, calorie-for-calorie. Studies that controlled total daily calories found no difference in fat gain or fat loss based on when carbohydrates were eaten. The mechanism people cite (insulin storage at night) does not survive contact with the data. What matters is whether eating most of your carbs at night helps or hurts your total daily intake. For some people it helps with sleep and adherence. For others it pushes them over their calorie target. Choose the distribution that makes your full-day macros sustainable.

When to ignore this calculator

The calculator is built for healthy adults using common goal categories. A few situations require professional input rather than a generic tool.

• Pregnancy and lactation. Calorie and protein needs rise during the second and third trimesters and during lactation. Defer to your obstetric care team for individualized targets.
• Chronic kidney disease. Protein recommendations for CKD are different and depend on stage. Talk to a nephrologist or registered dietitian.
• Eating disorders or recent recovery. A registered dietitian who specializes in eating disorders is a better fit than any generic calculator.
• Diabetes. Carbohydrate intake interacts directly with insulin dosing and glycemic control. Set carb targets with a clinician or certified diabetes educator, not a calculator.
• Elite or competitive athletes. Contest prep, weight-class sports, and high-volume endurance training all have specific peri-workout fueling and carb-periodization needs that go past what a general macro calculator covers. A sports dietitian is the right partner.

For everyone else, the numbers above are a defensible starting point. Hit your target consistently for two to three weeks, weigh yourself in a stable rhythm (same time, same conditions), and adjust based on the trend, not single days.

Related reading

References

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. doi:10.1093/ajcn/51.2.241
2. 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. doi:10.1136/bjsports-2017-097608
3. Aragon AA, Schoenfeld BJ, Wildman R, et al. "International society of sports nutrition position stand: diets and body composition." J Int Soc Sports Nutr. 2017;14:16. doi:10.1186/s12970-017-0174-y
4. 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. doi:10.1186/1550-2783-11-20
5. Phillips SM, Chevalier S, Leidy HJ. "Protein requirements beyond the RDA: implications for optimizing health." Appl Physiol Nutr Metab. 2016;41(5):565-572. doi:10.1139/apnm-2015-0550
6. 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. doi:10.1016/j.jamda.2013.05.021
7. Antonio J, Ellerbroek A, Silver T, et al. "A high protein diet (3.4 g/kg/d) combined with a heavy resistance training program improves body composition in healthy trained men and women." J Int Soc Sports Nutr. 2015;12:39. doi:10.1186/s12970-015-0100-0
8. Schoenfeld BJ, Aragon AA. "How much protein can the body use in a single meal for muscle-building? Implications for daily protein distribution." J Int Soc Sports Nutr. 2018;15:10. doi:10.1186/s12970-018-0215-1
9. Helms ER, Zinn C, Rowlands DS, Brown SR. "A systematic review of dietary protein during caloric restriction in resistance trained lean athletes: a case for higher intakes." Int J Sport Nutr Exerc Metab. 2014;24(2):127-138. doi:10.1123/ijsnem.2013-0054
10. Forbes GB. "Body fat content influences the body composition response to nutrition and exercise." Ann N Y Acad Sci. 2000;904:359-365. doi:10.1111/j.1749-6632.2000.tb06482.x
11. Garthe I, Raastad T, Refsnes PE, Koivisto A, Sundgot-Borgen J. "Effect of two different weight-loss rates on body composition and strength and power-related performance in elite athletes." Int J Sport Nutr Exerc Metab. 2011;21(2):97-104. doi:10.1123/ijsnem.21.2.97
12. Iraki J, Fitschen P, Espinar S, Helms E. "Nutrition recommendations for bodybuilders in the off-season: a narrative review." Sports (Basel). 2019;7(7):154. doi:10.3390/sports7070154

How this calculator differs from typical macro calculators

Most macro calculators online do one of three things: they hand back a fixed 40/30/30 percentage split that ignores body weight, they default to "moderate carb" or "low carb" templates with no anchoring to training stimulus, or they let protein float as a percentage of calories so the actual gram target shifts every time the user changes the calorie number. Most also collapse every goal into three buttons labelled lose, maintain, and gain, which hides the only decision that actually changes the outcome: how fast. A 10 percent deficit and a 25 percent deficit are both "lose weight" and they produce very different bodies at the end.

This calculator splits that decision into five named modes, each with a published band behind it, and tells you the projected weekly rate of change so you can check the mode against the scale instead of trusting it. Protein is anchored to body weight per the Morton 2018 meta-analysis (49 RCTs, n=1,863 in the British Journal of Sports Medicine) and then moved by the mode, with a hard floor on both cut modes, because protein is the lever that decides how much of a deficit comes out of muscle. Deficit depth is bounded by Helms 2014 and calibrated to the loss rates Garthe 2011 actually tested; surplus size follows the off-season band in Iraki 2019. Fat holds a 0.6 g/kg floor per the ISSN position stand (Aragon et al. 2017), carbohydrate takes the remainder, and the calorie target is never allowed below estimated BMR. The cost of doing things this way is more inputs and an honest range instead of a clean four-decimal answer. The benefit is that the macros you walk away with are ones you can defend.