My male veiled is a year old now...I actually thought he would get bigger? He eats well, etc. I have also never seen a fully mature adult 1st hand so maybe I'm expecting more??
Veileds vary dramatically in size and shape. But they will grow up to about the 18 month mark as stated. Some remain small, and some seem very large. I have a male that is well over 20" long, but his children are much smaller.