Macro Calculator — Cut, Maintain, or Bulk with Diet-Aware Splits

What This Calculator Does

The Macro Calculator returns your daily calorie target plus the exact protein / fat / carb breakdown in grams — calibrated to your goal (cut at three intensities, maintain, bulk at two intensities) and your diet preference (balanced, high-protein, keto, or mediterranean). Unlike most macro calculators that lock you into a fixed 40/30/30 ratio, this one anchors protein to bodyweight and adapts the fat target to your diet — the way modern sports nutrition guidance actually works.

The Three-Step Math

Step 1 — Calorie target

Mifflin-St Jeor is the most accurate BMR formula for the general population — it’s replaced the older Harris-Benedict in most clinical and sports-nutrition guidance because Harris-Benedict runs ~5% high. Activity multipliers go from 1.2 (sedentary) to 1.9 (extra active). Goal delta: −750 / −500 / −250 for cuts, 0 for maintain, +300 / +500 for bulks. The calculator floors at 1,200 kcal (women) / 1,500 kcal (men) for safety regardless of how aggressive your raw goal would have been.

Step 2 — Protein anchored to bodyweight

Protein needs scale with lean mass, not with how many calories you eat. The calculator picks a defensible point per goal:

• Aggressive cut (~1.5 lb/wk): 2.2 g/kg — maximum muscle preservation in a deep deficit
• Moderate cut (~1 lb/wk): 2.0 g/kg
• Gentle cut (~0.5 lb/wk): 1.8 g/kg
• Maintain: 1.6 g/kg — supports active training without overshooting
• Slow / fast bulk: 1.8 g/kg — supports new muscle without taking calories from carbs (the actual fuel for training)

Anywhere in the 1.6-2.4 g/kg range is reasonable for trained people; the calculator picks a single defensible point per goal. Sedentary, non-training adults can drop to 0.8-1.2 g/kg(the RDA + a buffer); the bodyweight anchor here assumes you’re training.

Step 3 — Fat by diet, carbs fill the rest

The diet preference sets fat as a percentage of your calorie target. Carbs fill whatever’s left after protein and fat. Keto is the exception — it caps carbs at ≤30 g and lets fat absorb the residual.

• Balanced (30% fat): the default. Most flexible across cuisines. Fat from olive oil, nuts, eggs, dairy, fatty fish; carbs from rice, oats, fruit, vegetables.
• High-protein (22% fat): leans on lean meats and protein supplements; carbs higher than balanced (more fuel for training). Useful when satiety is the limiting factor.
• Keto (≥65% fat, ≤30 g carbs): appetite- suppressing for some people; restrictive but well-tolerated when adherence is high. Watch electrolytes (sodium, potassium, magnesium) in the first 2 weeks.
• Mediterranean (35% fat): the most nutrient-dense option — emphasizes olive oil, fatty fish, nuts, whole grains, and vegetables. Strongest long-term cardiovascular evidence (PREDIMED trial and follow-ups).

A Worked Example — “75 kg, 30 yr, moderate activity, moderate cut, balanced diet”

Inputs: male, 30 yr, 175 cm, 75 kg, moderate activity (1.55), cut moderate (−500), balanced (30% fat).

• BMR:10 × 75 + 6.25 × 175 − 5 × 30 + 5 = 1,699 kcal
• TDEE: 1,699 × 1.55 = 2,633 kcal
• Target (cut): 2,633 − 500 = 2,133 kcal/day
• Protein: 75 kg × 2.0 g/kg = 150 g (600 kcal, 28% of total)
• Fat: 2,133 × 0.30 ÷ 9 = 71 g (640 kcal, 30% of total)
• Carbs: (2,133 − 600 − 640) ÷ 4 = 223 g (893 kcal, 42% of total)

Across 4 meals: ~533 kcal each, with 38 g protein / 18 g fat / 56 g carbs per meal— well above the ~30 g/meal protein threshold for muscle protein synthesis (MPS). That’s the “hit MPS every meal” sweet spot lifters target on cuts.

How Diet Preferences Compare at the Same Calorie Target

For the same 2,133 kcal cut (75 kg male, 150 g protein anchor):

• Balanced: 150 g P / 71 g F / 223 g C — the default, easiest to hit across cuisines
• High-protein: 150 g P / 52 g F / 266 g C — more carbs for training, fat from leaner sources
• Keto: 150 g P / 157 g F / 30 g C — fat dominates, carbs nearly eliminated
• Mediterranean: 150 g P / 83 g F / 197 g C — slightly higher fat, fat skewed toward olive oil and fatty fish

Pick the one you’ll actually adhere to. Adherence beats macro optimization every time— a balanced split you hit perfectly will outperform an “optimal” split you bail on by week 3.

How Aggressive Should Your Deficit / Surplus Be?

For cuts: 0.5-1% of bodyweight per weekis sustainable for most non-obese people. A 75 kg lifter targeting 0.75% loss = 0.56 kg/wk = ~−500 kcal/day deficit. Pushing harder (1.5-2 lb/wk for non-obese starters) typically backfires within 4-6 weeks: muscle loss accelerates, hunger spikes, training performance crashes, and the cut stalls.

For bulks: 0.5 lb/wk for intermediates, 1-2 lb/wk for true novices in their first year of consistent lifting. Faster bulks accumulate more fat than muscle and need a longer cut on the back end. The classic “dirty bulk” (1+ kg/wk) gains roughly 1:3 muscle:fat for trained lifters; a controlled +300 kcal bulk is closer to 1:1.

Common Mistakes

Underestimating cooking oils + sauces + drinks

The single biggest tracking error. A tablespoon of olive oil is 120 kcal; a typical restaurant entrée hides 2-4 tablespoons. Sauces, dressings, sweetened drinks, alcohol, and creamer all add up to 200-400 kcal/day for most people who haven’t weighed them. Track for 4-8 weeks with a kitchen scale — you’ll never look at a salad with vinaigrette the same way again.

Hitting protein only on average, not per meal

The MPS threshold (~30 g protein per meal) needs to be crossed every meal, not as a daily average. 150 g across breakfast (10), lunch (20), and dinner (120) is far inferior to 150 g across four 38 g meals. The scenario panel shows per-meal targets at 3-6 meal counts; pick the one that matches your eating schedule.

Switching diets every 2 weeks

Each diet preference has a 2-3 week adaptation window. Keto’s first 2 weeks involve electrolyte adjustment and the “keto flu.” Mediterranean takes a few weeks to dial in fat-source choices. Switching too fast means you’re always in the adaptation phase and never in the productive adherence phase. Pick one and stick with it for 8+ weeks before deciding it’s not for you.

Pulling all the deficit from carbs

On non-keto cuts, dropping carbs to zero in pursuit of a deficit crashes training performance and makes the cut harder to sustain. Keep at least 100 g carbs on training days for moderate-volume lifters; 150-200 g on high-volume programs. The deficit should come from total calorie reduction, not carb elimination.

Treating these numbers as exact

BMR formulas are accurate within ±10% for an average adult. Your actual maintenance can be 10-15% higher or lower than the calculator says. Use the target for 2-3 weeks, weigh yourself weekly, and adjust: gaining when you wanted to maintain → cut 100 kcal; losing too fast → add 150 kcal. The calculator gives you a starting point, not a destination.

What This Calculator Doesn’t Model

• Body composition.Lean mass needs more protein per kg than fat mass. The calculator uses total bodyweight; if you’re very lean (~10% body fat) or very obese (~30%+), adjust protein up or down by 10-15% from the calc’s number.
• Carb cycling. Periodizing carbs (lower on rest days, higher on training days, same weekly average) is a valid programming choice and well-tolerated. The calculator returns a daily average; cycling is layered on top.
• Refeed days. A weekly 1-day refeed (carbs + calories at maintenance) on long cuts can blunt metabolic adaptation and reset hormones (leptin, T3). Not modeled here; add it as a programming layer.
• Medical conditions. Insulin resistance, diabetes, thyroid disorders, and digestive conditions all change the math. Talk to a registered dietitian or your provider for individualized targets.
• Pregnancy / breastfeeding / postpartum. Calorie and protein needs change substantially in each phase and should be set by your provider, not a generic calculator.

Related Calculators

• TDEE— the calorie-only version. Use it if you don’t need the protein/fat/carbs breakdown and just want the maintenance number with goal adjustment.
• Protein Intake — protein-only deep dive. Explains the 1.6-2.4 g/kg range, the MPS threshold, and food-source examples to hit the daily target.
• One-Rep Max — if you’re lifting in support of these macros, run 1RM to set work weights for strength (5×5) or hypertrophy (3×8-10) blocks.
• BMI — population- level body weight signal. Pair with a body-fat percentage measurement for a fuller picture before picking your cut / maintain / bulk goal.

How to Read the Result

The protein gram targetis the non-negotiable floor — hit it daily within ±10% even if you miss other macros. Calorie total is a 7-day average, not a daily mandate; ±300 on any single day is normal. Track over a week, adjust on the scale trend, not yesterday’s plate.

• Cutting and protein under 1.6 g/kg. Bump protein to the top of the recommended range. Higher protein on a deficit preserves lean mass and dampens hunger — the single highest-leverage macro for body recomp.
• Bulking and gaining > 0.5 lb/wk.You’re gaining fat faster than muscle. Drop calorie surplus to +200/day; muscle gain caps at ~0.5 lb/wk for non-novices regardless of how much extra you eat.
• Two-week scale trend not moving in goal direction. Adjust calories ±200/day. Bodyweight isn’t responding to your math — your real maintenance differs from estimated TDEE by 10-15%, normal for individual variation.
• Keto with carbs > 50g.You’re not actually in ketosis. Either commit to < 30g and accept the first-week fatigue, or switch to standard balanced macros — half-keto loses both worlds.