Cutting Calculator

A cutting phase in bodybuilding targets body fat reduction while preserving as much lean muscle mass as possible. This requires a calculated calorie deficit: large enough to burn fat, small enough to stop the body breaking down muscle for fuel.

Step 1, calculate TDEE (Total Daily Energy Expenditure): TDEE = BMR × Activity Multiplier BMR (Mifflin-St Jeor, male) = 10×weight(kg) + 6.25×height(cm) − 5×age + 5 BMR (Mifflin-St Jeor, female) = 10×weight(kg) + 6.25×height(cm) − 5×age − 161

Activity multipliers:

• Sedentary (desk job, no exercise): × 1.2
• Light activity (1–3 days/week): × 1.375
• Moderate (4–5 days/week): × 1.55
• Very active (6–7 days/week, intense): × 1.725

Step 2, apply the deficit: Cutting Calories = TDEE − Deficit

• Slow cut: −300 kcal/day → ~0.6 lb (0.27 kg) fat loss per week
• Standard cut: −500 kcal/day → ~1 lb (0.45 kg) fat loss per week
• Aggressive cut: −750 kcal/day → ~1.5 lb fat loss per week (muscle loss risk increases)

Worked example: Male, 85 kg, 180 cm, 28 years old, trains 5 days/week. BMR = 10×85 + 6.25×180 − 5×28 + 5 = 850 + 1,125 − 140 + 5 = 1,840 kcal TDEE = 1,840 × 1.55 = 2,852 kcal Standard cut target: 2,852 − 500 = 2,352 kcal/day

Protein during a cut: Aim for 1.8–2.4 g protein per kg of body weight to preserve muscle. At 85 kg that is 153–204 g per day, and the calculator uses exactly this range.

Two guardrails the calculator applies that are worth knowing about. It will not hand you a target below 1,500 kcal for men or 1,200 for women, so if the deficit you choose would take you under, it stops there and says so. And it flags any plan losing more than about 1% of bodyweight a week, because past that the share of the loss coming from muscle rather than fat rises steeply, which defeats the purpose of cutting rather than simply dieting.

One honest caveat on the numbers. The 3,500 kcal per pound figure everyone uses is a linear approximation of a non-linear process. It holds well enough for the first few weeks and then overstates the loss, because a lighter body burns fewer calories doing the same things. The scale slowing after a month is expected, not a sign you have done something wrong.