My child's predicted height is 5'8 and when she turns 13 she's 5'7, then when she's 17.5 she's 5'6. See for yourself. I'm 5'6, my husband is 5'8, and my daughter is 5'6 at age 12. Is this true? Please explain to me.
The calculator takes your daughter's current height and attempts to project her height when she reaches adulthood. Your daughter is currently 5'6" at the age of twelve. Thus she is still within the typical range of a girl's growth spurt, though on the tail end. The formula projects she will grow another 2 or 3 inches. If you say she is 13, and still 5'6" she is past her growth spurt and only has an inch or so to go. If you say she is 17.5 and still 5'6" she is past the age of growing and won't gain any more height.
The calculator doesn't project a child's height at different ages, just the final height from a known starting point.
The "flaw" in the formula is that it doesn't take into account early or late puberty. Everything is based off the average growth pattern.