Casey Butt Calculator
Estimate frame-based muscular potential, projected bodyweight, and classical measurement targets.
Rare anthropometric profile in natural populations.
| MEASUREMENT | POTENTIAL |
|---|---|
| Chest | 47.5 in |
| Upper Arm | 16.9 in |
| Forearm | 13.6 in |
| Neck | 16.5 in |
| Thigh | 25.5 in |
| Calf | 17.1 in |
Casey Butt Potential Interpretation
These buckets interpret modelled normalized FFMI potential from frame-based anthropometric inputs.
| RANGE | CATEGORY |
|---|---|
| 0-20 | Modest Potential Lower projected FFMI ceiling. Progress still depends strongly on training quality and time. |
| 20-22 | Solid Potential Typical natural potential profile with room for meaningful development. |
| 22-24 | Advanced Potential Above-average anthropometric potential for muscular development. |
| 24-26 | Elite Natural Range High-end natural profile where most gains require long timelines and precision. |
| 26-28 | Exceptional Rare anthropometric profile in natural populations. |
| 28+ | Extreme Outlier Very uncommon model output. Re-check measurement inputs before interpretation. |
What This Casey Butt Calculator Estimates
This tool applies a Casey Butt style anthropometric model using height, wrist circumference, and ankle circumference to estimate potential bodyweight and lean mass at a chosen body-fat level. It also estimates classical circumference targets.
How The Model Works
Casey Butt style models assume bone-structure inputs (wrist and ankle) are practical proxies for frame potential. Height and frame inputs are combined to project a muscular endpoint at selected body-fat percentage.
This is best interpreted as a structured estimate, not a hard biological maximum.
How To Use It With Other Muscle Tools
For a frame-adjusted FFMI ceiling model, compare with the Muscular Potential Calculator. For current lean-mass status versus natural screening ranges, compare with the Natty or Not Calculator and FFMI Calculator.
If body-fat inputs are uncertain, validate with the Body Fat Calculator or photo-based estimate tool.
For a combined score that blends structural leverage with projected FFMI potential, compare with the Bodybuilding Genetics Calculator.
Important Caveats
The original Casey Butt framework is male-focused and based on specific bodybuilding-era assumptions. This page provides a scaled estimate for women, but precision is lower outside the original data context.
All anthropometric models are sensitive to body-fat and circumference error. Repeat measurements with consistent protocol for better trend quality.
References
- Kouri EM, et al. Fat-free mass index in users and nonusers of anabolic-androgenic steroids.PubMed record
- Lee RC, et al. Anthropometric prediction model for total-body skeletal muscle mass.PubMed record
- Cintineo HP, et al. Sport differences in fat-free mass index in NCAA athletes.PubMed record
More Muscle Tools →
FFMI Calculator
How much of you is muscle?
Natty or Not Calculator
Compare your frame-adjusted FFMI against common natural muscularity ceilings.
Muscular Potential Calculator
Estimate modelled natural lean-mass potential from frame-adjusted FFMI limits.
Bodybuilding Genetics Calculator
Estimate a modelled bodybuilding genetics score from structure and FFMI-based potential.