How big should a lean bulk surplus be?

A moderate surplus of about 200 to 300 kcal per day supports muscle growth while limiting fat gain, especially for trained lifters. Larger surpluses add weight faster but most of the extra is fat, so a conservative surplus is preferred for a lean bulk.

What deficit is right for cutting?

A deficit of roughly 400 to 500 kcal per day strips fat at about 0.4 to 0.5 kg per week while preserving muscle, particularly when protein is high and training is maintained. Aggressive deficits risk muscle and performance loss.

How is weekly weight change estimated?

About 7700 kcal equals one kilogram of body mass, so the daily surplus or deficit times seven, divided by 7700, gives the estimated weekly change in kilograms. It is a planning estimate, not a guarantee, since metabolism adapts over time.

How is TDEE estimated if I do not know mine?

The tool can multiply your bodyweight by a per-kilogram factor scaled by an activity level. This is a rough estimate; tracking your actual intake and weight trend over two to three weeks gives a far more accurate personal TDEE.

Why might my real results differ?

Water weight, glycogen, sodium, and metabolic adaptation all move the scale independently of fat and muscle. Judge progress over three to four weeks of trend data rather than day-to-day readings, and adjust intake if the trend stalls.

Athlete Lean Bulk / Cut Calorie Calculator

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Changing body composition comes down to energy balance: a modest surplus to build muscle, a deficit to lose fat. This calculator turns your maintenance level into a concrete daily target and estimates how fast your weight should move.

How it works

The target is your maintenance energy expenditure plus or minus a goal-based adjustment, and weekly change follows the energy-balance rule:

TDEE          = entered, or bodyweight(kg) × 33 × activity factor
target        = TDEE + adjustment
  lean bulk   adjustment = +250 kcal
  cut         adjustment = −450 kcal
  maintenance adjustment = 0
weekly change = (adjustment × 7) / 7700  kg per week

Roughly 7700 kcal corresponds to one kilogram of body mass, which is why a small daily adjustment translates into a slow, sustainable weekly rate.

Example and tips

An athlete with a 2800 kcal TDEE on a lean bulk eats about 3050 kcal per day and gains roughly 0.23 kg per week — slow enough that most of it is lean mass. On a cut the same person eats about 2350 kcal and loses around 0.41 kg per week. Keep protein high in both phases and judge progress over three to four weeks of trend data, not daily scale readings.