What is the best alternative to BMI?

There is no single best alternative — each measures something different. Waist-based ratios add fat distribution, body fat estimates add composition, and DEXA gives the most complete and accurate picture but requires a clinic visit and cost. Pick based on what question you actually want answered.

Is BRI or RFM better than BMI?

Both incorporate waist circumference, which BMI ignores entirely, so both capture information BMI structurally cannot. Neither has the decades of population research behind it that BMI has, so treat them as complementary tools rather than drop-in replacements.

A Body Shape Index (ABSI) is another waist-based alternative that combines waist circumference, height and weight into a single shape metric. It isn't calculated on this site yet, but it belongs in the same family as BRI and the waist ratios — measures that add what BMI leaves out.

Do I need to choose just one measure?

No — most of these tools take seconds to calculate and are free. Using BMI alongside a waist-based measure and a body fat estimate gives a fuller picture than any single number, at essentially no extra cost.

BMI Alternatives Compared

No single alternative replaces BMI outright — each one answers a different question BMI cannot. This table compares the free, calculator-based options alongside the clinical reference standard.

Comparison

BMI alternatives compared
Measure	Inputs	Tells you	Cost
Body Roundness Index (BRI)	Waist, height	Body shape / central adiposity estimate	Free
Relative Fat Mass (RFM)	Waist, height, sex	Body fat percentage estimate	Free
Waist-to-hip ratio (WHR)	Waist, hip, sex	Fat distribution (apple vs pear shape)	Free
Waist-to-height ratio (WHtR)	Waist, height	Fat distribution, single 0.5 threshold	Free
Body fat percentage (tape/Navy method)	Neck, waist, (hip for women), height	Body fat percentage estimate	Free
DEXA scan	Low-dose X-ray scan	Precise fat, lean tissue and bone breakdown	Clinic visit, paid

Notes on each

Body Roundness Index (BRI):: Newer (2013), no weight needed, still an emerging research measure
Relative Fat Mass (RFM):: Simple, validated against DEXA in NHANES data
Waist-to-hip ratio (WHR):: WHO sex-specific risk thresholds
Waist-to-height ratio (WHtR):: No sex-specific cutoffs needed
Body fat percentage (tape/Navy method):: Typical error 3-4 points vs DEXA
DEXA scan:: The practical reference standard

Try them

Common questions

What is the best alternative to BMI?: There is no single best alternative — each measures something different. Waist-based ratios add fat distribution, body fat estimates add composition, and DEXA gives the most complete and accurate picture but requires a clinic visit and cost. Pick based on what question you actually want answered.
Is BRI or RFM better than BMI?: Both incorporate waist circumference, which BMI ignores entirely, so both capture information BMI structurally cannot. Neither has the decades of population research behind it that BMI has, so treat them as complementary tools rather than drop-in replacements.
What is ABSI?: A Body Shape Index (ABSI) is another waist-based alternative that combines waist circumference, height and weight into a single shape metric. It isn't calculated on this site yet, but it belongs in the same family as BRI and the waist ratios — measures that add what BMI leaves out.
Do I need to choose just one measure?: No — most of these tools take seconds to calculate and are free. Using BMI alongside a waist-based measure and a body fat estimate gives a fuller picture than any single number, at essentially no extra cost.