Cutting macros calculator

What is a cutting phase?

A cut is a period of deliberate calorie restriction designed to reduce body fat while preserving as much muscle as possible. Done well, you lose 0.5–1% of bodyweight per week, keep your strength in the gym, and end the cut looking leaner without feeling depleted. Done badly, you lose strength, muscle, and motivation — and rebound within weeks of finishing.

Two variables determine outcome:

• Deficit size — how aggressive the cut is. Bigger deficits lose weight faster but risk muscle loss and bad adherence.
• Protein intake — how much muscle you protect. Under-protein cuts lose 30–50% of weight as lean mass; properly protein'd cuts lose 90%+ from fat.

Everything else (carb timing, meal frequency, fasted cardio) is a rounding error next to these two.

How to use this calculator

1. Enter your TDEE. Run the TDEE Calculator first if you don't know it.
2. Enter your current bodyweight.
3. Set your deficit — 300–500 kcal/day is the recommended range for most people. This produces 0.5–1% of bodyweight lost per week.
4. Click Calculate Cutting Macros. You'll see daily calories, protein, fat, and carbs plus estimated weekly fat loss.
5. Track daily in a logging app and weigh yourself every morning. Use weekly averages, not daily numbers, to assess progress.

The formula

Calories  = TDEE − deficit
Protein   = max(bodyweight × 2.4 g/kg, 1 g/kg)  ← muscle-sparing floor
Fat       = 25% of total calories ÷ 9 kcal/g
Carbs     = remaining calories ÷ 4 kcal/g

Weekly fat loss ≈ (deficit × 7) ÷ 7,700 kcal/kg

Why the deficit range is 300–500 kcal

Smaller (under 300 kcal) is fine but slow — useful for people who are already lean or need long, low-stress cuts. Larger (over 500 kcal) accelerates loss but stacks problems:

• Muscle loss risk rises sharply past 750 kcal/day deficit, especially in lean trainees
• Adherence collapses as hunger exceeds what diet discipline can offset
• Metabolic adaptation kicks in harder — bigger deficits mean bigger NEAT reductions, so the "real" deficit shrinks within weeks
• Training performance drops, degrading the stimulus that protects muscle

Deficits above 1,000 kcal/day are flagged in this calculator because at that level, research shows muscle loss equals or exceeds fat loss in all but the most obese starting points.

Why protein is 2.4 g/kg on a cut (vs 2.2 for maintenance)

Protein needs climb during a calorie deficit. A 2014 study (Longland et al., American Journal of Clinical Nutrition) compared 1.2 vs 2.4 g/kg protein in a 6-week cut — the high-protein group lost fat and gained muscle despite being in a 40% deficit; the low-protein group lost both. A 2013 review (Helms et al.) set the evidence-based range for lean, trained dieters at 2.3–3.1 g/kg bodyweight. 2.4 g/kg is a pragmatic middle of that range.

Why 25% fat, carbs as remainder

Fat below 20% of calories on a cut risks testosterone drop, especially in men and especially in long cuts. 25% is a safety margin. Carbs get whatever's left — usually 30–45% of calories — which is enough to fuel training without crowding protein or fat out.

How to interpret your result

• Weekly loss target: 0.5–1% of bodyweight. An 80 kg person should lose 0.4–0.8 kg/week. Faster means muscle loss; slower means the deficit is too small.
• If loss stalls for 2+ weeks: real TDEE has dropped below the estimate (metabolic adaptation). Subtract 100–150 kcal from carbs and retest for 2 weeks.
• If loss is too fast (>1% per week): muscle is at risk. Add 100–150 kcal in carbs.
• If strength drops more than 10%: calories are too low or protein too low. Re-check both.

Diet breaks and refeeds

Cuts longer than 8 weeks benefit from structured breaks:

• Refeed day — 1 day/week at maintenance calories, extra calories from carbs. Restores muscle glycogen and leptin briefly.
• Diet break — every 6–8 weeks, raise calories to maintenance for 7–14 days. Re-prime metabolism, recover mentally, then resume the cut.

These aren't mandatory — short cuts (under 8 weeks) don't need them — but they improve adherence and long-term outcomes.

Cardio: useful but not the driver

The cut is driven by the deficit. Cardio adds to the deficit but doesn't replace it.

• 2–3 low-intensity sessions (30–45 min, zone 2) per week improves recovery and eats calories without interfering with lifting
• Add cardio when diet adherence is already solid. Don't use it to compensate for over-eating
• Fasted vs fed doesn't matter for fat loss in the long run

Common mistakes

• Cutting too aggressively. Most people pick 750–1000 kcal deficits, lose strength, lose muscle, and rebound. Stay in the 300–500 range unless you're very overweight.
• Forgetting to recalculate. Every 4–5 kg lost, recompute TDEE — your new bodyweight burns fewer calories at rest.
• Ignoring protein. The entire muscle-protection strategy of a cut rests on protein. Hit it daily within ±5 g.
• Weighing once a week. Daily bodyweight is noisy (up to ±2 kg from water, food, sodium). Use 7-day moving averages.

What to do next

• If you haven't tested your TDEE, run the TDEE Calculator first.
• Track body fat changes with the Body Fat Calculator every 4 weeks.
• When the cut is over and you're ready to build muscle, switch to the Bulking Macros Calculator.

Related tools

• TDEE Calculator — find your calorie baseline
• Macro Calculator — maintenance macros
• Bulking Macros Calculator — after the cut
• Body Fat Calculator — track fat loss progress

Calories  = TDEE − deficit
Protein   = max(bodyweight × 2.4 g/kg, 1 g/kg)  ← muscle-sparing floor
Fat       = 25% of total calories ÷ 9 kcal/g
Carbs     = remaining calories ÷ 4 kcal/g

Weekly fat loss ≈ (deficit × 7) ÷ 7,700 kcal/kg