According to this Wyatt is the height of a 3yr old at 18months and Keegan is 1inch off the height of a 4yr old :-)
Hey, I found this really awesome Etsy listing at https://www.etsy.com/listing/199639824/wooden-height-chart-childrens-growth
DIY Ruler Growth Chart
"Average" weight and height of children, babies to teenagers.
Child Growth Chart Calculator
CUSTOM Painted Ruler Growth Chart / Wood Growth Chart by RouxBeeLu
$5 +30 minute wooden growth chart. Who knew it was so easy. Click here for instructions.
Cute growth chart! http://www.etsy.com/listing/153130893/custom-painted-ruler-growth-chart-wood
42 Craft Project Ideas That are Easy to Make and Sell | Big DIY IDeas ~ an oversize yardstick would make a great gag gift that's actually useful too!