This method derives from a 1948 article by Horace Gray in the journal Child Development,[1] X Research source Gray H. “Prediction of Adult Stature. ” Child Development 1948; 19, 3: 167-75. and is still in widespread use today. The margin of error is +/- 4 inches (10. 2 cm), which may seem like a large amount (consider the difference of ending up either 5'2" or 5'10"), but is indicative of the difficulty of accurately predicting height in the face of so many variables.
For instance, if the father of a female child is 69 inches (180 cm), multiply by 12, then divide by 13, for an adjusted result of 63. 7 inches. Likewise, if the mother of a male child is 63 inches (160 cm), multiply by 13, then divide by 12, for an adjusted result of 68. 3 inches.
The formulas: ((69 x 12 / 13) + 63) / 2 = 63. 3 [female child]; (69 + (63 x 13 / 12)) / 2 = 68. 7 [male child]. There are also websites that will do the calculations for you if you enter the required heights. Remember that with the range of accuracy in this method, the female child in the example above could reasonably expect to reach between 59. 3 and 67. 3 inches, based on assorted genetic and environmental factors.
Thus, for a female child, ((69 + 63) / 2) - 3 = 63 inches (160 cm), or ((69 +63) / 2) -5 = 61 inches. Or, for a male child, ((69 + 63) / 2) + 3 = 69 inches (180 cm), or ((69 + 63) / 2) + 5 = 71 inches.
For instance, a female child who is 32 inches (81. 3 cm) at 18 months would be predicted to reach 64 inches (160 cm) (5’4”), while a male child who is 36 inches (91. 4 cm) at 2 years would be predicted to reach 72 inches (180 cm) (6’). The +/- 4 inch (10. 2 cm) margin of error stands for this method as well.
This method is recommended for children ages 4 and above. Unless you really want to test your math skills, rely on a website calculator to make this determination. For example, a 40-inch, 45-pound, 4-year old female child, with a mother at 63 inches (160 cm) and father at 69 inches, is predicted to reach 63 inches (160 cm) (5’3”). The 90% margin of error for this method is approximately 2 inches (5. 1 cm), meaning 90% of children with the above criteria would reach between 61 and 65 inches.
This one is obviously not a do-at-home prediction method. Discuss your interest in this method with your child’s physician. This method is considered somewhat (but not substantially) more accurate than the Khamis-Roche Method.
Released in 2005,[8] X Research source this method utilizes the child’s sex, date of birth, date of test, height, sitting height, and weight. There are online calculators for this method as well. For example, a female child born May 5, 2003; tested May 5, 2015; height 63 inches (160 cm); sitting height 49 inches; weight 120 pounds; can expect to reach 64. 7 inches (164. 3 cm) (5’5”).
