Fitness and Health
FFMI Calculator
FFMI Calculator calculate fat-free mass index, fat mass index, and height-normalized FFMI from weight, height, and body-fat percentage.
Fitness and Health
FFMI Calculator
Calculate fat-free mass index, fat mass index, and height-normalized FFMI from weight, height, and body-fat percentage.
Formula
FFMI = fat-free mass kg / height m^2; normalized FFMI = FFMI + 6.3 x (1.80 - height m).
About the FFMI Calculator
Calculate fat-free mass index, fat mass index, and height-normalized FFMI from weight, height, and body-fat percentage.
How the FFMI Calculator Works
Body weight is split into fat and fat-free mass with the entered body-fat percentage; both are indexed to height and FFMI is normalized to 1.80 m.
Formula
FFMI = fat-free mass kg / height m^2; normalized FFMI = FFMI + 6.3 x (1.80 - height m).
The calculation runs in your browser. Values are validated for required ranges, compatible units, and method-specific restrictions before results are displayed.
Required Inputs
- Body weight (required) - enter in kg.
- Height (required) - enter in cm.
- Body fat (required) - enter in %.
Results Reported
The result panel reports the final answer and the intermediate quantities needed to check the calculation:
- Fat-free mass (kg)
- Fat mass (kg)
- Fat-free mass index
- Height-normalized FFMI
- Fat mass index
FFMI Calculator Example
Select Example Data in the calculator to load this reproducible input set:
| Input | Example value |
|---|---|
| Body weight | 82 kg |
| Height | 180 cm |
| Body fat | 15 % |
How to Use the Calculator
- Confirm that the calculator title and formula match the quantity you need.
- Enter every required value using the unit shown with its field.
- Select Example Data to inspect a valid input set, or enter your own values and select Calculate.
- Review all reported values and the displayed formula before using the answer.
- Use Copy Result or Download CSV when you need a reusable record.
Accuracy and Limitations
Body-fat measurement error directly affects FFMI. The height normalization was published for male athletes and should not be treated as a diagnosis or universal natural-limit test.
Keep units consistent, use measurements that represent the actual situation, retain full precision during the calculation, and round only the final answer. Professional decisions may require current official rules, field measurements, laboratory methods, or specialist review.
Frequently Asked Questions
What does the FFMI Calculator calculate?
Calculate fat-free mass index, fat mass index, and height-normalized FFMI from weight, height, and body-fat percentage.
Which formula does the FFMI Calculator use?
FFMI = fat-free mass kg / height m^2; normalized FFMI = FFMI + 6.3 x (1.80 - height m). Body weight is split into fat and fat-free mass with the entered body-fat percentage; both are indexed to height and FFMI is normalized to 1.80 m.
What should I check before using the FFMI Calculator result?
Body-fat measurement error directly affects FFMI. The height normalization was published for male athletes and should not be treated as a diagnosis or universal natural-limit test.