This calculator determines your daily calorie and macronutrient targets using validated predictive equations. Choose the formula that matches your population, set your goal, and adjust the protein/fat/carbohydrate split to your protocol.
Macro Calculator
ProHow this calculator works
The calculator follows the standard three-step pipeline a sports dietitian uses: estimate resting metabolism (BMR), multiply by activity to get total daily energy expenditure (TDEE), then apply a surplus or deficit to match the goal. The macro split is layered on top, with protein set per kilogram of body weight — the approach with the strongest evidence behind it — and fat as a percentage of calories, with carbohydrates filling the remainder.
Choosing the right BMR formula
| Formula | Best for | Needs body fat? |
|---|---|---|
| Mifflin-St Jeor | General adult population (15–65, BMI 18–40). The most validated modern equation; the default in clinical settings. | No |
| Katch-McArdle | Athletes with known lean mass. More accurate than Mifflin for very lean or very muscular individuals because it accounts for metabolically active muscle tissue. | Yes |
| Cunningham | Elite endurance and strength athletes with low body fat. Tends to give higher BMR estimates; useful for competitors who feel underfuelled on Mifflin. | Yes |
| Harris-Benedict (1984) | Older adults and populations where Mifflin underestimates. Include it as a cross-check when a client's real-world weight trend diverges from Mifflin-based targets. | No |
The Auto option selects Katch-McArdle when you enter body fat (the most precise option at that point) and falls back to Mifflin-St Jeor otherwise.
Protein: the macro that matters most
Protein is the one macronutrient where the evidence is unambiguous: 1.6–2.2 g per kg of body weight per day maximises muscle protein synthesis in nearly every population studied, from sedentary adults to elite strength athletes. Below 1.6 g/kg, you leave gains on the table; above 2.2 g/kg, the additional benefit approaches zero for muscle but may help with satiety during a cut. The Protein Intake Calculator gives a standalone gram target if you only need that one number.
| Goal | Protein (g/kg) | Why |
|---|---|---|
| Aggressive cut (−20%) | 2.4–3.0 | Higher protein preserves lean mass in a large deficit and increases satiety |
| Moderate cut (−10%) | 2.0–2.4 | Sufficient to prevent muscle loss without excessive calories from protein |
| Maintenance / recomp | 1.8–2.2 | Supports training recovery and marginal lean-tissue gain at maintenance calories |
| Lean bulk (+10%) | 1.6–2.0 | Surplus calories already anabolic; extra protein yields diminishing returns |
| Surplus bulk (+20%) | 1.4–1.8 | Large surplus covers protein needs; excessive protein displaces training carbs |
Fat and the hormone argument
Dietary fat has two hard floors: a minimum of ~0.8 g/kg (or ~20% of calories) to support testosterone production, cell-membrane integrity, and fat-soluble vitamin absorption. Below that, endocrine markers degrade in 2–3 weeks. The practical range is 20–35% of total calories, with 25% a sensible default that leaves room for carbohydrates.
For ketogenic protocols, fat jumps to 60–75% of calories and protein stays moderate (1.5–2.0 g/kg). The calculator handles this automatically when you use the keto preset — protein is fixed, fat is set high, and carbs collapse to the remainder. The long-term efficacy and safety of ketogenic protocols relative to more moderate splits remains an active area of research, worth discussing with a dietitian before committing to it long-term.
Carbohydrates: the performance lever
Once protein and fat are set, carbohydrates fill the rest. This is correct because carbs are the only macro whose optimal intake depends on the calories left over rather than on a per-kg target. The practical ranges:
- Sedentary: 1–3 g/kg (enough for brain and basic function)
- General training 3–5×/wk: 3–5 g/kg
- Strength/hypertrophy 5–6×/wk: 4–6 g/kg
- Endurance athlete: 5–10 g/kg (race week can exceed 12)
Why the goal percentage is a starting point, not a prescription
The ±20% surplus/deficit built into each goal option is a first approximation, not a law. Real metabolic adaptation means a 10% deficit rarely produces exactly 10% of projected weight loss — the body compensates by reducing spontaneous movement (NEAT), lowering resting metabolic rate slightly, and increasing hunger. The correct professional approach is:
- Start with the calculated target.
- Execute consistently for 14–21 days, tracking average daily weight and adherence.
- Compare the actual weight trend to the projected rate shown above.
- Adjust by 100–200 kcal if the trend diverges by more than 0.3% body weight per week.
- Recalculate every 4–6 weeks as weight changes — the same deficit in absolute kcal shrinks as you get leaner.
Training-day carbohydrate timing
The "Training-day option" card shifts ~25% of daily carbs into the pre-workout window (60–90 min before), 30% of protein into the post-workout window (within 2 hours after), and reserves ~10% of carbs for intra-session if training exceeds 90 minutes. This is not mandatory — total daily intake dominates timing for body composition — but it improves session quality, particularly on a cut where glycogen is the limiting factor. Coaches tracking strength progress alongside nutrition may also find the One-Rep Max Calculator useful.
Frequently asked questions
Why is my maintenance calorie number different from another calculator?
Three reasons: the BMR formula used (Mifflin vs Harris-Benedict can differ by 5–10%), the activity multiplier (some calculators use 1.4 for "moderate" while others use 1.55), and whether body fat was entered. The difference is usually 150–300 kcal, which is within normal individual variation. Pick one calculator, use it consistently, and adjust based on real-world results.
Should I set protein per kg of total weight or lean mass?
Per kg of total body weight is the standard used in the research literature and the one this calculator applies. Using lean mass can under-protein overweight individuals by 30–40%. If you prefer lean-mass-based protein, use the Lean Body Mass Calculator first, then multiply by 1.6–2.2 g/kg — though this is rarely worth the extra step for most people.
I'm on a keto diet — why does the calculator still show carbs?
With the keto preset (65% fat), the carb figure will typically be under 30 g — that's the remainder after protein and fat. If it's higher, your calorie target is very high relative to your weight; in that case, increase the fat percentage until carbs drop below 30 g, or switch to a per-kg carb target of 0.5 g/kg for strict keto.
Can I use this for a client who is pregnant or breastfeeding?
Not directly. The formulas were validated on non-pregnant adults. Pregnancy adds ~300–500 kcal/day in the second and third trimester, and breastfeeding adds ~500 kcal/day. Protein needs rise to 1.1 g/kg (pregnancy) and 1.3 g/kg (lactation). Use this calculator for the base estimate, then add the obstetric adjustments — the Pregnancy Weight Gain Calculator covers the related weight-gain targets — and refer to a registered dietitian for the full protocol.
Why does the aggressive cut show 2.4–3.0 g/kg protein — isn't that too high?
No. Multiple controlled trials show that lean athletes in a large deficit preserve more lean mass at 2.4–3.0 g/kg than at 2.0. The cost is satiety and food volume, not kidney function — the "high protein damages kidneys" claim has been refuted in every long-term study on healthy individuals.
My weight isn't changing on the calculated deficit. What's wrong?
Most likely: under-reporting intake (the average person underestimates by 20–30%), metabolic adaptation (NEAT drops more than predicted), or water masking fat loss (especially in women's luteal phase or after a high-sodium/carb day). Track for 14 days, take the weekly average, and if the average is still flat, reduce the target by 150–200 kcal.
Should I count net carbs or total carbs?
For general and athletic populations, total carbohydrates (as shown here). For ketogenic diets, net carbs (total minus fibre) is the relevant figure — keep under 25–30 g net for nutritional ketosis. The calculator shows total carbs; subtract the fibre target shown in the reference card to get net.
Is the water intake recommendation accurate?
It's a baseline (33 ml per kg body weight) from EFSA and IoM guidance. Add 500–1000 ml for each hour of training, more in heat. The simplest rule: urine should be pale yellow by mid-afternoon — adjust from there.
What does the protein lock button do?
Locking protein keeps your current g/kg value fixed when you click a macro preset button — only fat and carbs adjust. Useful if you've already dialed in a specific protein target with a client and want to try different fat/carb splits around it without resetting protein each time.
Sources and validation
- Mifflin MD, St Jeor ST, et al. "A new predictive equation for resting energy expenditure in healthy individuals." Am J Clin Nutr, 1990;51(2):241–247. — the default BMR formula.
- McArdle WD, Katch FI, Katch VL. "Exercise Physiology: Energy, Nutrition & Human Performance." Lippincott Williams & Wilkins. — Katch-McArdle lean-mass equation.
- Cunningham JJ. "A reanalysis of the factors influencing basal metabolic rate in normal adults." Am J Clin Nutr, 1980;33(11):2372–2374.
- Roza AM, Shizgal HM. "The Harris Benedict equation reevaluated." Am J Clin Nutr, 1984;40(5):986–992. — revised Harris-Benedict coefficients.
- Helms ER, Aragon AA, Fitschen PJ. "Evidence-based recommendations for natural bodybuilding contest preparation." J Int Soc Sports Nutr, 2014;11:20. — protein ranges for cutting (2.4–3.0 g/kg).
- Morton RW, 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." Br J Sports Med, 2018;52:376–385. — 1.6 g/kg ceiling for MPS.
- Institute of Medicine (US). Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids. National Academies Press, 2005. — AI for water (35 ml/kg) and fibre (14 g/1000 kcal).
Related calculators
See the full list of Health calculators, or try:
- BMI Calculator — body mass index and category
- BMR Calculator — basal metabolic rate only
- Calorie Calculator — TDEE and weight-loss timeline
- TDEE Calculator — maintenance calories by activity
- Body Fat Calculator — Navy and Jackson-Pollock methods
- Water Intake Calculator — daily fluid target from body weight and activity
- Fiber Intake Calculator — daily fibre target by age, sex, and calories
- Ideal Weight Calculator — reference weight ranges by height and frame
- Protein Intake Calculator — standalone protein gram target by body weight
- One-Rep Max Calculator — estimated 1RM from a submaximal lift