How many extra calories do I need to bulk?

A lean bulk requires a surplus of 10-15% above your TDEE (roughly 1,000-2,000 kJ extra per day). An aggressive bulk uses 15-20% surplus. Most people can gain 0.25-0.5 kg of muscle per week as beginners, so a large surplus just adds unnecessary fat.

What is the difference between lean bulk and dirty bulk?

A lean bulk uses a controlled surplus (10-15%) with high protein and nutritious foods to minimise fat gain. A dirty bulk ignores calorie limits and food quality, leading to faster weight gain but significantly more body fat. Lean bulking is recommended for most people.

How much protein do I need while bulking?

Aim for 1.8-2.2 g/kg of body weight per day. This calculator uses 2.0 g/kg as the default, which is supported by research as optimal for muscle growth during a caloric surplus. Going higher than 2.2 g/kg shows no additional benefit.

How long should a bulk last?

A typical bulk phase lasts 3-6 months, depending on your starting body fat percentage. If you start lean (10-15% body fat for men, 18-23% for women), you can bulk longer. Once you reach about 18-20% body fat (men) or 28-30% (women), consider transitioning to a cut.

Bulking Calculator

This Bulking Calculator helps you work out how many calories and macronutrients you need to gain muscle effectively. Choose between a lean bulk (10-15% surplus) for minimal fat gain or an aggressive bulk (15-20% surplus) for faster muscle growth. Get personalised daily targets for protein, carbohydrates, and fat based on your body stats and activity level.

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Gender

Age

years

Weight

Height

Activity Level

Bulk Type

How It Works

The calculator estimates your TDEE using the Mifflin-St Jeor equation, then adds a caloric surplus (10-20% above maintenance). Protein is set at 2.0 g/kg to maximise muscle protein synthesis. Fat is set at 0.8-1.0 g/kg for hormonal health. The remaining calories are allocated to carbohydrates, which fuel training performance. A lean bulk minimises fat gain while an aggressive bulk prioritises faster overall weight gain.

Quick Reference

Parameter	Lean Bulk	Aggressive Bulk	Notes
Calorie Surplus	+10-15%	+15-20%	Above TDEE
Protein	2.0 g/kg	2.0 g/kg	Same for both approaches
Fat	0.8-1.0 g/kg	0.8-1.0 g/kg	For hormonal health
Carbohydrates	Remainder	Remainder	Fills remaining calories
Weekly Weight Gain	0.25-0.4 kg	0.4-0.6 kg	Target range
Monthly Muscle Gain	~0.5-1.0 kg	~0.5-1.0 kg	Beginners gain more
Fat Gain Risk	Minimal	Moderate	Trade-off with muscle gain
Recommended For	Most lifters	Hardgainers / beginners	Start lean, switch if needed
Duration	3-6 months	3-4 months	Until ~18-20% BF (men)
Training Focus	Progressive overload	Volume + progressive overload	Strength gains are key

Monthly muscle gain rates assume consistent resistance training 3-5 days per week with adequate sleep and recovery.

Frequently Asked Questions

How many extra calories do I need to bulk?: A lean bulk requires a surplus of 10-15% above your TDEE (roughly 1,000-2,000 kJ extra per day). An aggressive bulk uses 15-20% surplus. Most people can gain 0.25-0.5 kg of muscle per week as beginners, so a large surplus just adds unnecessary fat.
What is the difference between lean bulk and dirty bulk?: A lean bulk uses a controlled surplus (10-15%) with high protein and nutritious foods to minimise fat gain. A dirty bulk ignores calorie limits and food quality, leading to faster weight gain but significantly more body fat. Lean bulking is recommended for most people.
How much protein do I need while bulking?: Aim for 1.8-2.2 g/kg of body weight per day. This calculator uses 2.0 g/kg as the default, which is supported by research as optimal for muscle growth during a caloric surplus. Going higher than 2.2 g/kg shows no additional benefit.
How long should a bulk last?: A typical bulk phase lasts 3-6 months, depending on your starting body fat percentage. If you start lean (10-15% body fat for men, 18-23% for women), you can bulk longer. Once you reach about 18-20% body fat (men) or 28-30% (women), consider transitioning to a cut.

How This Is Calculated

BMR = (10 x weight in kg) + (6.25 x height in cm) - (5 x age) +/- gender offset TDEE = BMR x activity multiplier Bulk Calories = TDEE x (1 + surplus %) Protein (g) = body weight (kg) x 2.0 Fat (g) = body weight (kg) x 0.9 Carbs (g) = (Bulk Calories - Protein kcal - Fat kcal) / 4

+10-15%: = Lean bulk surplus above TDEE
+15-20%: = Aggressive bulk surplus above TDEE
2.0 g/kg: = Protein target for muscle protein synthesis
0.9 g/kg: = Fat target (mid-range) for hormonal health
7,700 kcal/kg: = Approximate energy in 1 kg of body mass gain

Uses the Mifflin-St Jeor equation for BMR estimation. Protein is fixed at 2.0 g/kg based on ISSN recommendations for muscle gain. Fat supports testosterone production and should not go below 0.6 g/kg.

Related Tools

Cutting Calculator

Calculate your calorie deficit and macro split for cutting. Preserve muscle while losing fat with optimised nutrition.

Protein Intake Calculator

Calculate your daily protein needs based on body weight, activity level, and fitness goal. Includes Australian dietary guidelines.

TDEE Calculator

Calculate your Total Daily Energy Expenditure using the Mifflin-St Jeor equation. See how many calories and kilojoules you burn per day.

Disclaimer

This calculator provides estimates for informational purposes only and should not be considered medical advice. Individual results may vary based on factors not captured by these formulas. Consult a healthcare professional before making changes to your diet or exercise routine, especially if you have any existing health conditions.