Mifflin-St Jeor based

TDEE Calculator for Bulking

Bulking requires eating above your TDEE to build muscle. This calculator finds your maintenance calories using the Mifflin-St Jeor equation and adds a calorie surplus based on your bulking goal — lean, standard, or aggressive.

Mifflin-St Jeor equation · Lean, standard & aggressive bulk targets
No signup required Mifflin-St Jeor formula Bulk targets included
Your gender
Your height
Your weight
Your bulk calorie targets
Maintenance
—
kcal / day
Your TDEE baseline
Lean Bulk
—
kcal / day
+250 kcal · minimal fat gain
Standard Bulk
—
kcal / day
+500 kcal · ~0.45 kg/week
Your BMR — Calories burned at complete rest
Aggressive bulk (+750 kcal) — Fast gain · higher fat accumulation
Calculated using the Mifflin-St Jeor equation
These estimates are for informational purposes only and are not medical advice. Consult a registered dietitian or healthcare professional for personalised guidance.
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How Bulking Works

Bulking is the practice of eating in a calorie surplus to provide the energy your body needs to build new muscle tissue. Without sufficient calories, muscle growth is severely limited even with perfect training.

The key is choosing the right surplus size. Too small and progress stalls. Too large and you accumulate excess fat that requires a longer cutting phase to remove.

+250 kcal/day → Lean bulk: ~0.25 kg/week, mostly muscle
+500 kcal/day → Standard bulk: ~0.45 kg/week, muscle + some fat
+750 kcal/day → Aggressive bulk: ~0.68 kg/week, higher fat accumulation
Example — 28-year-old male, 78 kg, very active:

TDEE = 3,100 kcal/day

Lean bulk = 3,100 + 250 = 3,350 kcal/day

Standard bulk = 3,100 + 500 = 3,600 kcal/day

Your Personalised Bulk Targets

Protein During a Bulk

Protein is the most important macronutrient during a bulk. Aim for 1.6–2.2 g per kg of bodyweight per day. This ensures your body has enough amino acids to maximise muscle protein synthesis during the surplus.

After hitting your protein target, fill the remaining calories primarily with carbohydrates — which fuel training performance and recovery — and a moderate amount of healthy fats.

Protein: 1.6–2.2 g × bodyweight (kg)
Carbs: fill ~45–50% of remaining calories
Fat: fill ~20–25% of total calories

More Calorie Tools

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Calorie surplus targets for lean weight and muscle gain with minimal fat.
BMR Calculator
Find your resting metabolic rate — the baseline for all calorie calculations.

Frequently Asked Questions

How many calories should I eat to bulk? +
Eat 250–500 calories above your TDEE. A 250 kcal surplus produces lean muscle gain with minimal fat. A 500 kcal surplus builds faster but adds more fat. Most people get the best results from a 250–350 kcal surplus.
How long should a bulk last? +
Most bulking phases last 3–6 months. Bulk until your body fat reaches 15–18% for men or 25–28% for women, then cut back to 10–12% for men or 18–22% for women before bulking again.
Should I do a clean bulk or dirty bulk? +
A clean bulk uses a small 250–500 kcal surplus with whole foods, gaining mostly muscle with minimal fat. A dirty bulk uses a large surplus with any foods, gaining weight faster but with much more fat. Clean bulking produces better long-term body composition results.
How much muscle can I gain per month bulking? +
Natural lifters typically gain 0.5–1 kg of muscle per month in optimal conditions. Beginners may gain slightly faster. Advanced lifters gain slower — often 0.25–0.5 kg per month. Most weight gain during a bulk includes some fat regardless of how clean your diet is.
What should my macros be while bulking? +
A good starting point is 30–35% protein, 40–50% carbs, 20–25% fat. Prioritise hitting your protein target first (2 g per kg bodyweight), then fill remaining calories with carbs for training energy and fats for hormonal health.