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Bulk & Cut Calculator

Calculate your exact calories and macros for muscle building or fat loss. Get a personalized plan based on your body, activity level and goal.

What does bulking and cutting mean?

Bulking and cutting are the two main phases of body recomposition. In a bulk, the goal is to build muscle mass by eating a calorie surplus and training hard. In a cut, the goal is to reduce body fat through a calorie deficit while preserving the muscle built during the bulk.

Successful body composition change requires knowing the right calorie target for your phase. Too large a surplus during a bulk leads to excessive fat gain, and too aggressive a cut risks losing muscle mass. This calculator finds the right calorie level for your specific goal, body and activity level.

The calculator uses the Mifflin-St Jeor equation — the most validated formula for estimating basal metabolic rate — combined with your activity multiplier to calculate your TDEE (total daily energy expenditure). Your target calories and macros are then calculated from that baseline.

Lean bulk vs. aggressive bulk

🎯 Lean Bulk

Small calorie surplus (+200–300 kcal). Muscle grows more slowly but fat gain is minimized. Best suited for experienced lifters who want to minimize the need for a long cut afterward.

🚀 Aggressive Bulk

Larger calorie surplus (+500–600 kcal). Muscle grows faster but more fat is also gained. Best suited for beginners and underweight lifters who can take advantage of beginner gains.

The role of protein when bulking and cutting

Protein is the building block of muscle tissue. During a bulk, adequate protein (1.6–2.0 g/kg) ensures that the calorie surplus is channeled toward muscle growth rather than fat. During a cut, protein needs are even higher (2.0–2.4 g/kg) — sufficient protein intake is the most important factor for preserving muscle mass while in a calorie deficit. This calculator sets protein targets automatically based on your goal and adjusts carbohydrates and fat to fill the remaining calories.

Frequently asked questions

Bulking is a muscle-building phase where you eat a calorie surplus to support muscle growth. Cutting is a fat loss phase where you eat a calorie deficit while aiming to preserve the muscle you have built. Both phases are key parts of body composition training.
A lean bulk uses approximately 200–300 kcal surplus per day. An aggressive bulk can use 400–600 kcal surplus. A larger surplus does not build muscle faster — it mainly adds more body fat. Most research supports a modest surplus of 200–350 kcal for optimal muscle gain with minimal fat gain.
A safe calorie deficit is approximately 300–500 kcal per day, corresponding to roughly 0.3–0.7 kg of weight loss per week. Too aggressive a cut can lead to muscle mass loss, reduced strength and impaired recovery. A moderate deficit with high protein intake preserves the most muscle.
When bulking, approximately 1.6–2.0 g of protein per kg of bodyweight is sufficient. When cutting, protein needs are higher — around 2.0–2.4 g per kg — because adequate protein helps preserve muscle mass during a calorie deficit. This calculator automatically adjusts protein targets based on your goal.
A bulking phase typically lasts 3–6 months and a cutting phase 2–4 months. The length depends on your starting point and goals. Phases that are too short do not produce sufficient results. Most experienced lifters alternate between multiple bulk and cut cycles over the course of a year.

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