according to BMI:
according to WHtR: ≤ 85.5 cm, ≤ 2 ft 9.66 in
Probability of being overweight.
Source: BROWNING, Lucy M., HSIEH, Shiun Dong and ASHWELL, Margaret, 2010. A systematic review of waist-to-height ratio as a screening tool for the prediction of cardiovascular disease and diabetes: 0·5 could be a suitable global boundary value. Nutrition Research Reviews. December 2010. Vol. 23, no. 2, p. 247–269. DOI 10.1017/S0954422410000144.
IMPORTANT: No mathematical formula has been found yet to be a definitive predictor of being overweight or underweight. They just serve as indications of statistical risk, but they can be wrong. However, only a physician can diagnose whether someone is overweight, obese, or suffers of any disease. Please consult your physician.