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At a glance: FFMI chart
| Topic | What to record or compare | Interpretation limit |
|---|---|---|
| Inputs | Weight, height, and body fat estimate | Bad body fat input makes FFMI unreliable |
| Interpretation | Compare broad ranges, not identity labels | Frame size and estimation error matter |
| Use case | Context for muscularity over time | Not a verdict on training quality |
Calculate before assigning a label
Fat-free mass = weight × (1 − body-fat fraction). Raw FFMI = fat-free mass ÷ height². The commonly cited height adjustment adds 6.3 × (1.80 − height in metres) to raw FFMI.
The 1995 study included 157 male athletes and described the findings as preliminary. Its normalization and observed range should not be turned into a universal “natural limit,” a female chart, or an accusation about drug use. Read natural physique context for that boundary.
Worked FFMI examples, not population percentiles
These examples show the arithmetic for two sets of adult inputs; they are not target physiques or sex-specific health standards.
| Example | Height | Weight / entered fat | Fat-free mass | Raw / normalized FFMI |
|---|---|---|---|---|
| A | 1.80 m | 80 kg / 20% | 64 kg | 19.75 / 19.75 |
| B | 1.65 m | 60 kg / 25% | 45 kg | 16.53 / 17.47 |
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Upload a photo to LeanLens, get a confidence-aware read, and use the article framework to choose one practical next step.
Show a range when the input is uncertain
At 80 kg and 1.80 m, changing the body-fat input from 15% to 20% changes raw FFMI from about 20.99 to 19.75. That 1.24-point spread can come entirely from the entered estimate; it does not prove a change in muscle.
Use the FFMI calculator with the same height and weight at several plausible body-fat inputs. Track the method beside the number. A chart that hides input uncertainty can encourage false precision.
Limits and safety
LeanLens content is informational fitness guidance, not medical advice, diagnosis, or treatment. Photo-based analysis should be used for trend direction and practical next steps, not clinical decisions.
FAQ
Does FFMI over 25 prove steroid use?
No. A historical observation in a specific male sample is not an individual drug test or universal biological ceiling.
Can women calculate FFMI?
The arithmetic works, but the often-cited male study does not establish female percentiles or targets. Interpretation needs appropriate population and measurement context.