The AnthroCalcUK app uses the “British 1990 Growth Reference, reanalyzed 2009” to calculate percentiles and Z-scores for length/height, weight, body-mass index (BMI), head circumference, sitting height, leg length, waist circumference, percent body fat, and blood pressure for typically growing children and youth ages birth to 23 years; and for length, weight and head circumference for preterm infants born at 23 to 42 weeks gestation.