I haven't really gotten into the size of my dragons, but I figured that a reasonable reference point for the size of my dragons would be Tyrannosaurus rex, since my dragons, as adults, look like miniature T. rexes with wings. The arms become less important the bigger the dragons get, so after some time, the arms will stop growing but every other part of the dragon's body keeps growing. This means that when juveniles become bipedal(yes, they start quadrapedal and lizard-like in appearance), their proportion of arm:body is more like that of a Velociraptor and then as they grow, the arms become tiny in comparison to the rest of the body, like how it is in T rex.
This actually makes sense, as these dragons are the apex predators in their environment. And, they would certainly be longer than a human is tall. Having large arms more like those of a human, or even the forelimbs of a dog, would make it hard for them to fly if they would even be able to fly. This doesn't affect juveniles as much because of how small they are, but it really affects the adults. Having small arms in comparison to the body helps with the aerodynamics by reducing drag. And drag reduction is important in a flying creature, avian or not. So, it would make sense that the arms would reach a maximum size, while the legs and the rest of the body keeps growing.
Now for the size of my dragons as adults. I figured that a reasonable length for them would be 15 feet, which is 3/8 the length of T. rex. To keep things proportional, I calculated the height to be 6.375 feet which is 6' 4.5", taller than your average human, but not that much taller. Since the mass, if I'm not mistaken, has roughly an inverse cube relationship with the length and height, this means that it wouldn't be 3/8 the mass but rather, more like 19x less massive than T. rex, which would make it have a mass of 1,637.6 lbs. But, I might be wrong on that so correct me if I am.
Anyway, given the size of my dragons as adults, how big would the wings have to be in order for them to fly?