Bulking Calculator – Calculate Your Calorie Surplus & Macros for Muscle Gain

  • Adam
  • January 2, 2026

Free bulking calculator to determine your daily calories, protein, carbs, and fats for muscle gain. Plan your lean bulk or aggressive bulk with science-based formulas and weekly tracking.

Bulking Calculator

Calculate your daily calorie targets and optimal macronutrient split for building muscle. Whether you're planning a lean bulk or aggressive bulk, this science-based calculator provides personalized targets based on your body stats, activity level, and goals.

Your Information

Please enter a realistic age between 15 and 100.
Please enter a realistic height.
Please enter a realistic weight.
Standard bulk: 250–450 kcal surplus, moderate muscle gain with manageable fat gain.
Optional: advanced settings ▼
Body fat is optional, but it can improve protein targets for leaner individuals.
If you already know your maintenance calories, enter them here.
Manually adjust your daily calorie surplus.
Daily Bulking Target
—
calories per day
Estimated Maintenance Calories
—
Daily Calorie Surplus
—
Projected Weekly Weight Gain
—

Macro Breakdown

—
Protein
— kcal
—
Carbs
— kcal
—
Fat
— kcal
Make your bulk easier to follow
  • Simple macro targets in grams
  • Printable weekly plan
Explore nutrition tools

Weekly Plan & Progress

WeekDate RangeAvg CaloriesProtein (g)Carbs (g)Fat (g)Expected WeightNotes
Click "Calculate" to generate your weekly plan

How It Works

This bulking calculator uses scientifically validated formulas to determine your daily calorie and macronutrient needs for muscle growth.

Basal Metabolic Rate (BMR)

We use the Mifflin-St Jeor equation to estimate your resting metabolism:

Male: \( BMR = 10W + 6.25H - 5A + 5 \)

Female: \( BMR = 10W + 6.25H - 5A - 161 \)

Where \( W \) = weight in kg, \( H \) = height in cm, \( A \) = age in years

Total Daily Energy Expenditure (TDEE)

Your maintenance calories account for activity level:

\( TDEE = BMR \times ActivityFactor \)

Activity factors range from 1.2 (sedentary) to 1.9 (athlete-level training).

Bulking Target Calories

Your target adds a controlled surplus for muscle growth:

\( Target = TDEE + Surplus \)

Surplus recommendations: Lean bulk (150–300 kcal), Standard (250–450 kcal), Aggressive (400–700 kcal).

Macronutrient Distribution

Protein: 1.6–2.2 g/kg body weight for optimal muscle protein synthesis

Fat: 0.6–1.0 g/kg or 20–30% of total calories

Carbs: Remaining calories after protein and fat:

\( Carbs_g = \frac{Target - (Protein_g \times 4 + Fat_g \times 9)}{4} \)

Projected Weight Gain

Estimated weekly gain based on calorie surplus:

\( WeeklyGain_{kg} \approx \frac{Surplus \times 7}{7700} \)

Note: Individual results vary based on training, genetics, and recovery.

Lean Bulking Tips

  • Progressive overload: Increase weights, reps, or volume gradually to stimulate muscle growth.
  • Prioritize sleep: Aim for 7–9 hours nightly for optimal recovery and hormone production.
  • Hit protein targets daily: Distribute protein across 3–5 meals for sustained muscle protein synthesis.
  • Track your weight weekly: Weigh yourself at the same time each week to monitor trends, not daily fluctuations.
  • Adjust surplus if needed: If gaining too fast (>0.5 kg/week), reduce surplus by 100–200 kcal.
  • Stay hydrated: Drink adequate water, especially when increasing carbohydrate intake.
  • Choose whole foods: Prioritize nutrient-dense foods over processed options for better performance and health.

Frequently Asked Questions

How many calories should I eat for bulking?
Your bulking calories should be 5–20% above your maintenance calories (TDEE). For most people, this means a surplus of 200–500 kcal per day. A conservative surplus of 250–350 kcal minimizes fat gain while supporting muscle growth.
What is the difference between lean bulk and dirty bulk?
A lean bulk uses a moderate calorie surplus (200–300 kcal) and focuses on whole, nutrient-dense foods to maximize muscle gain while minimizing fat gain. A dirty bulk involves a large surplus with less attention to food quality, leading to faster weight gain but more fat accumulation.
How much protein do I need when bulking?
Research supports 1.6–2.2 grams of protein per kilogram of body weight daily for optimal muscle protein synthesis during bulking. For a 70 kg person, this equals 112–154 grams per day. Higher protein intakes (up to 2.2 g/kg) may benefit those with lower body fat percentages.
What is a calorie surplus and why is it needed?
A calorie surplus means consuming more calories than your body burns daily. This surplus provides the extra energy required for building new muscle tissue through resistance training. Without a surplus, your body lacks the resources needed for optimal muscle growth.
How fast should I gain weight when bulking?
Aim for 0.25–0.5 kg (0.5–1 lb) per week for lean muscle gain with minimal fat. Beginners may gain faster initially. Gaining more than 0.5 kg weekly typically indicates excessive fat accumulation and suggests reducing your calorie surplus.
What activity level should I choose?
Choose based on your total weekly activity: Sedentary (desk job, minimal exercise), Light (1–3 workout days), Moderate (3–5 workout days), Very Active (6–7 workout days), or Athlete (training 2x daily or very intense sessions). Consider both gym time and daily movement.
Can I build muscle without a calorie surplus?
Beginners and those returning from a training break can build muscle at maintenance calories or even in a slight deficit, especially with adequate protein intake (2+ g/kg). However, experienced lifters typically require a calorie surplus for continued muscle growth.
How do I calculate my maintenance calories?
Maintenance calories (TDEE) are calculated by multiplying your Basal Metabolic Rate (BMR) by an activity factor (1.2–1.9). The BMR represents calories burned at rest, determined by your weight, height, age, and sex using the Mifflin-St Jeor equation.
Should I adjust my macros over time?
Yes. As your weight increases, recalculate your targets every 4–8 weeks. Your maintenance calories rise as you gain weight, so you may need to increase total calories to maintain the same surplus. Protein needs also increase slightly with added body weight.
Can I export my bulking plan?
Yes! This calculator allows you to export your complete plan as a CSV file, which you can open in Excel or Google Sheets. You can also use the print-friendly version to create a physical reference for your bulk.

About This Calculator

The Bulking Calculator was created by OmniCalculator.Space to provide evidence-based nutrition guidance for individuals looking to build muscle mass through structured calorie and macronutrient planning.

Our calculator uses validated formulas from sports nutrition research and applies conservative surplus recommendations to help you gain muscle while minimizing unnecessary fat accumulation. All calculations are performed client-side—your data never leaves your device.

Scientific References

This calculator is based on established research in sports nutrition and energy metabolism:

Disclaimer: This calculator provides educational estimates only and is not a substitute for professional medical or nutritional advice. Individual calorie and macronutrient needs vary based on genetics, metabolism, training intensity, and health status. Consult with a registered dietitian or healthcare provider before making significant dietary changes, especially if you have underlying health conditions.

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