Muscle Tools
Bodybuilding Genetics Calculator
Estimate a modelled bodybuilding genetics score from structure and FFMI-based potential.
Casey Butt Calculator
Estimate frame-based bodybuilding potential from height, wrist, and ankle measures.
FFMI Calculator
How much of you is muscle?
Lean Body Mass Calculator
Estimate your lean mass with standard equations.
Muscle Mass Calculator
Estimate skeletal muscle mass from anthropometric measurements.
Muscular Potential Calculator
Estimate modelled natural lean-mass potential from frame-adjusted FFMI limits.
Natty or Not Calculator
Compare your frame-adjusted FFMI against common natural muscularity ceilings.
How To Use Muscle Tools Effectively
This category currently includes 7 tools. Choose one baseline tool first, then add one or two supporting tools for cross-checking.
Muscle tools are most useful when you want structure, not hype. This category helps you estimate natural potential, compare lean-mass context, and set realistic expectations based on frame and body composition assumptions.
Use these calculators for long-range planning and trend direction. Do not treat one output as a hard limit. The strongest signal comes from repeated measurements, stable training inputs, and consistency over months.
What This Category Is Best For
- Natural potential planning: Use Muscular Potential and Casey Butt to set realistic lean-mass targets.
- Contextualizing FFMI: Use Natty or Not and Bodybuilding Genetics tools to compare where you sit versus model ranges.
- Program checkpoints: Recheck every 8-12 weeks instead of reacting to weekly fluctuations.
Input Quality Checklist
- Measure height, wrist, and ankle consistently and at the same time of day.
- Use body-fat estimates from the same method when possible to reduce formula drift.
- Track training age and body-weight trend alongside each result snapshot.
Interpretation Notes
- Treat outputs as planning ranges, not exact predictions.
- Frame-based tools are sensitive to circumference measurement quality.
- Compare your trend against your own baseline first, then population references.
Common Mistakes To Avoid
- Comparing outputs from different methods as if they are identical measurements.
- Changing multiple inputs between check-ins and assuming one variable caused the change.
- Using short-term fluctuations to rewrite long-term training expectations.
Recommended Starting Tool: Muscular Potential Calculator
Start here for a practical, frame-aware estimate of long-term natural lean-mass potential.