According to
this resource, your handsome guy is within a healthy normal range.
Cockatiel - 5287 samples, 91g mean, 82-100g ±10% range
Determining the normal weight of a bird type is not an exact science. While I can come up with a specific number, there are many other variables to consider.
For example, some individuals are normally large, others are petite. Sometimes there’s a weight difference based on sex or age. There are regional size
differences and subspecies' size variation for some birds. One of these bird types listed (Eclectus parrots) includes all the different species. So the average
(mean) weight presented here is not set in stone. Regardless, I still consider the number presented as accurate, especially when it includes a weight range of
10% on either side of the mean. So, for example, if the mean weight of a Green-Cheeked Conure is 66g, then the normal weight range would be 60 - 72g.