Waist-to-hip ratio calculator

A hip circumference of zero makes the ratio undefined, so the API returns a clear invalid_input error instead of inventing infinity.

How to call the API and what comes back

Waist and hip must be finite positive numbers within one thousand units of the chosen system; sex must normalize to male or female (accepted shortcuts include m, f, man, woman). Send a JSON body with three required fields: waist (aliases waist_cm, waist_in, w, waist_circumference), hip (aliases hip_cm, hip_in, h, hip_circumference, hips), and sex (aliases gender, sex_at_birth, biological_sex). Optionally set unit (aliases units, measure, circumference_unit) to cm or in as a display label only—the numeric ratio does not change with the unit string. On success the response echoes rounded waist, hip, sex, and unit; sets ratio and whr to the same rounded quotient; sets risk_band and risk to low, moderate, or high; publishes thresholds with moderate_at and high_at for the selected sex; and includes formula, message, and an ordered steps array showing the division and band decision. Failed validation—missing fields, non-finite numbers, zero or negative waist or hip, unknown sex or unit, values outside published limits, or a non-finite quotient—returns invalid_input and is never charged. Pricing is a flat $0.002 per successful request with unit item and zero marginal unit price.

Practical tips, limits, and related searches

Prefer sending numbers rather than pre-formatted strings when you control the client; string numbers are accepted only when they match a strict finite numeric pattern. Use sex consistently with the thresholds you intend to report: male and female cut-offs differ, and this tool does not invent a third band set for other gender labels. Prefer this capability when you already have two girths and sex and only need the ratio plus band; if your source is a photo or wearable, extract those three scalars first. Measure waist and hips with the same tape and the same unit before you call the API; mixing centimetres for waist with inches for hip silently corrupts the ratio. Keep circumferences inside the published maximum of one thousand so intermediate products stay finite on the Worker and in the browser. When educating patients or users, pair examples: female waist eighty and hip one hundred yields zero point eight zero moderate; female waist eighty-five and hip one hundred yields zero point eight five high; male waist ninety and hip one hundred yields zero point nine zero moderate; male waist one hundred and hip one hundred yields one point zero zero high; and hip equals zero demonstrates the hard invalid_input path. This landing targets people searching for a waist-to-hip ratio calculator, WHR calculator, or body-shape health-risk band online; it is not a BMI calculator, not a body-fat percentage estimator, not a medical diagnosis, and not a full metabolic panel. Failed tasks that return invalid_input do not consume prepaid balance, which keeps exploratory scripts cheap when you deliberately send a zero hip to test client validation. Round-trip checks are easy: recompute waist divided by hip by hand and confirm it equals the published ratio within twelve-decimal rounding, and confirm that crossing only the high threshold flips risk_band between moderate and high for the documented sex.