How the CrossFit macro calculator works

This macro calculator for athletes sets daily calories, protein, carbs and fat for competitive CrossFit and functional fitness athletes. It uses five inputs: sex, bodyweight, a body-fat range, weekly training hours and how much of that training is intense. It does not need height or age, because it estimates metabolism from lean mass.

A 185 lb man with healthy body fat who trains 10 hours a week (40% intense) gets about 3,430 calories: 173 g protein, 471 g carbs and 95 g fat. A 140 lb woman with the same settings gets about 2,610 calories: 119 g protein, 371 g carbs and 73 g fat.

The steps

1. Lean mass: bodyweight × (1 − body-fat %)
2. Resting metabolism (Cunningham): 500 + 22 × lean mass (kg)
3. Daily life and digestion: resting metabolism × 1.3
4. Training burn: weekly hours × net METs × bodyweight (kg) ÷ 7, with intense hours at 9 net METs and other hours at 4
5. Calorie target: maintenance +10% (very lean), maintenance (healthy) or −10% (slightly overfat)
6. Protein: 2.2, 2.4 or 2.8 g per kg of lean mass
7. Fat: 25% of calories, or 20% in a deficit
8. Carbs: the calories left over, checked against ACSM's carb ranges for your training load

Assumptions and why we made them

Body-fat ranges

Most athletes don't know their exact body fat, so the calculator uses three ranges and a representative value inside each. Each range also sets the calorie target, shown on its button: very lean gets a 10% surplus, healthy gets maintenance and slightly overfat gets a 10% deficit.

The ranges follow the American Council on Exercise chart, where athletes run 6–13% (men) and 14–20% (women) and the fitness range is 14–17% and 21–24%. Women carry about 8 points more essential fat, so their ranges sit 8 points higher.

Calorie adjustment: +10%, maintenance or −10%

Competitive athletes need energy to train and recover, so the adjustments stay small. Very lean athletes get a 10% surplus to support performance and muscle gain without much fat gain; Precision Nutrition uses the same +10% for its athletic performance goal. Slightly overfat athletes get a 10% deficit, at the gentle end of the 10–15% that Working Against Gravity recommends for CrossFit athletes, so training quality holds up.

Resting metabolism from lean mass

The Cunningham equation needs only lean mass. The ACSM position stand on athletic performance names it for athletes, and a 2023 meta-analysis of athlete studies found it had no meaningful bias. Muscular athletes burn more at rest than height-and-age formulas predict, which lean-mass equations account for.

Training intensity: 9 vs. 4 net METs

A MET is the energy cost of an activity relative to rest. Measured CrossFit workouts run high: "Cindy" averaged 9.5 METs and "Fran" burned 12–20 calories per minute. Strength, skill and easy aerobic work run lower, around 5–6 METs in the Compendium of Physical Activities. The calculator uses 9 METs above rest for intense hours and 4 for everything else. At 40% intense, that averages 6 METs per training hour.

Protein from lean mass

Basing protein on lean mass keeps heavier athletes with more body fat from getting inflated targets. The results land at about 1.8–2.3 g per kg of bodyweight, the top of the International Society of Sports Nutrition range (1.4–2.0 g/kg). Protein goes up in a deficit to protect muscle, as Helms et al. recommend (2.3–3.1 g/kg of lean mass).

Fat at 25% (20% in a deficit)

ACSM advises athletes not to go below 20% of calories from fat long term. The calculator uses 25% normally and drops to 20% in a deficit, so more of a smaller calorie budget goes to carbs for training.

Carbs fill the rest

Carbs fuel intense training, so they get the remaining calories. The result is checked against ACSM ranges: 3–5 g/kg for light training, 5–7 for about an hour a day, 6–10 for 1–3 hours a day and 8–12 for 4–5 hours a day.

Adjusting each macro

Every athlete responds a little differently, so each macro can be set to Low, Regular or High. Low cuts that macro's share of calories by 20% and High raises it by 20%; the other two macros scale to keep total calories the same. This lets an athlete who trains better on more carbs, or prefers more fat, change the split without changing the energy target. If fat drops under 20% of calories, the calculator notes that ACSM advises against staying there long term.

A training scale weighted toward 0–20 hours

Most competitive athletes train between 5 and 20 hours a week, so the slider gives that range most of its length. It is evenly spaced from 0 to 10 hours (about half the slider), then hours get gradually closer together: 20 hours sits about three-quarters of the way along, and 20–40 hours share the last quarter. A thin line marks each hour, and every setting moves in half-hour steps.

Low-energy warning

If calories left after training fall below 30 per kg of lean mass, the calculator shows a warning. The International Olympic Committee links that level to low energy availability (RED-S), which can hurt hormones, bone health and performance.

Example results

Frequently asked questions

More free tools for CrossFit coaches and athletes: see all ZOAR tools, including the erg calculator.

Sources

• Thomas et al. 2016, ACSM/AND/DC position stand: Nutrition and Athletic Performance
• Jäger et al. 2017, ISSN position stand: protein and exercise
• Helms, Aragon and Fitschen 2014, nutrition for natural physique athletes
• IOC 2023 consensus statement on REDs
• O'Neill et al. 2023, resting metabolic rate equations in athletes
• 2024 Adult Compendium of Physical Activities
• ACE: energy cost of CrossFit workouts and Kliszczewicz et al. 2014, "Cindy"
• Precision Nutrition calculator method and Working Against Gravity macro guide

Updated November 9, 2026. For healthy adult athletes; not medical advice.