It is not easy to estimate the size of a baby bearded dragon then it is grown. The size and length of bearded dragons depend on some factors such as the breed, their living environment, their diet and their sex.
But generally, you can expect that your fully grown bearded dragons can reach 18-20 inches in length from their head to the tip of the tail. But if your bearded dragons are not growing as normal, there are some things that you should consider to ensure the good condition of growth for your pet.
#1 They are not getting enough UVB light
UVB is regarded as beneficial for bearded dragons grown. UVB provides Vitamin D3, which helps bearded dragons appropriately absorb calcium from their diet. Without calcium, bearded dragon bones will be weak and brittle, impeding the growth of bones.
Besides, do not exposure enough with UVB light can lead to the suppressed appetite of your bearded dragons, lacking of nutrients lead to the stop of growth.
#2 Your bearded dragons do not have a proper diet
In the 6 first months of bearded dragons life, the baby will grow very quickly, they require enough protein as much as they can eat to grow. If your bearded dragons are under 3 months old, they need to be fed 5 times per day, each time last 10-15 minutes. And you should expect that they eat as much as possible.
#3 They are bromated when they young
Brumation can know as the hibernation of reptile when the winter comes. When this process taking place, your bearded dragons tend to spend most of the time to sleep and they do not need to eat. So they will lose their weigh.
But when you allow them to be bromated at a young age, they will waste their ideal time of growth. This is the reason why the brumation stunt the growth of your bearded dragons.
In order to avoid this, you should maintain the constant temperature in their cage all the time and also maintain the day/night cycle is normal every day.