Calculator · Lean Bulk Calculator
Plan a lean bulk: calorie surplus and bodyweight trend
This calculator combines estimated TDEE with internal surplus and bodyweight-trend rules based on training experience. It provides planning starting points — not a prediction of how much muscle or fat will be gained.
Result
- TDEE
- 2,720kcal/day
- Target calories (lean bulk)
- 2,992kcal/day
- Planning gain range
- 0.15–0.26kg/week
- Protein planning target
- 150g/day
10 % surplus, +272 kcal/day.
Internal range based on training experience and bodyweight; not a muscle-gain prediction.
~2.0 g/kg.
If bodyweight rises clearly faster than the planning range, review the surplus and the underlying data. Rapid weight gain alone proves neither disproportionate fat gain nor muscle gain.
Surplus and weight trend are model starting values. They do not predict what share of later weight gain will be muscle or fat.
Method
How the calculation works
TDEE is first estimated with Mifflin-St Jeor plus an activity factor. That total-expenditure number is itself a model and can differ individually.
The calculation then uses fixed percentage surplus and bodyweight-gain ranges by selected training experience. These are internal planning heuristics, not individually validated optimal values.
The protein value of about 2.0 g/kg is a simple planning anchor inside commonly studied ranges for active adults.
Methodology: formulas, assumptions and estimate confidence →
Estimate confidence
How reliable is this estimate?
Medium
The calculator uses established energy and protein anchors, but TDEE, experience tiers and the composition of weight gain remain individually uncertain.
Interpretation
How to read your result
Judge bodyweight across several weeks. Faster gain does not automatically mean more muscle; bodyweight also includes fat, water, glycogen and gut contents.
Training, recovery, experience and starting point influence how an energy surplus affects body composition. The calculator cannot predict those factors.
Limits
Where this calculator ends
Estimated TDEE includes a broad activity factor and is not measured energy expenditure.
The experience-based surplus and bodyweight-trend rules are model heuristics. They quantify neither muscle-protein synthesis nor the later split of muscle and fat within weight gain.
The calculator is intended as a general planning tool for adults. Underweight, medical conditions or special nutrition circumstances belong in professional care.
Common mistakes
Common mistakes
- 01Equating bodyweight gain with muscle gain.
- 02Treating the experience-based surplus as individually optimal.
- 03Reacting to single scale readings instead of a multi-week trend.
- 04Ignoring training and recovery when judging the surplus.
- 05Treating TDEE as measured rather than estimated.
Example
A worked example
Illustrative example: 75 kg, intermediate, moderately active
The model estimates TDEE and applies the internal surplus for the selected experience tier. The displayed kg/week range is a monitoring target — not a forecast of new muscle mass.
FAQ
Frequently asked questions
- Is the calculated surplus optimal?
- No. It is an experience-based starting value in this model. Observe bodyweight, training, hunger, digestion and well-being across several weeks.
- Does weight gain mean muscle gain?
- Not automatically. Bodyweight includes muscle, fat, water, glycogen and gut contents. The scale alone cannot determine the composition of gain.
- Why does training experience change the model range?
- The calculation uses training experience as a rough proxy for changing potential progress rates over a training career. It is a planning heuristic, not an individual forecast.
- When should I adjust the surplus?
- Only after several consistent weeks. Check data quality and daily movement first, then make small changes if the trend clearly sits outside the desired range.
- How much protein is required?
- The tool uses about 2.0 g/kg as a simple planning anchor. The suitable individual intake depends on the whole diet, energy intake, body composition and goal.
Sources
Sources
More
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