https://pubmed.ncbi.nlm.nih.gov/25552209/

Found an interesting study done on a rather small population size that found the following regression equation for height to head circumference:

Y = 1.734X + 70.36 (R2 = 0.196) for male

Y = 0.916X + 106.8 (R2 = 0.091) for female

and Y = 1.648 X + 71.69 (R2 = 0.158) for combined (male and female)

where Y is the height of Individual and X is the Head Circumference.

My head circumference is 56.4cm, and plugging it into the equation for males yields a height of 168.2cm, which is BANG ON my height after being on my feet all day.

To be fair, the following publication contradicts the association between height and head circumference, stating that the two have different pathways of growth mostly independent of each other: https://pubmed.ncbi.nlm.nih.gov/28068308/

Just some food for thought. Is this equation accurate for you folks?

Another proportionality aspect is skull height, but I do not have any data to make an association here. I'm sure there is a correlation but the skull height percentage difference is less than the total height percentage difference. Shouldn't be an issue for lengthening under 10cm.