This is my first attempt at a feats calculation, so I apologize for errors.
For those of you who do not know, Fragor is the name for the small spherical reiryoku blast that Aizen fired at Ichigo in Deicide.
Calculations for the attack by a ChaosTheory123 were already done on Naruto Forums for Outskirts Battledome. He treated the depth of the crater as being equal to the diameter of the crater. He claims it is generous, and that 9,314,941.1 m^3 is the most believable high-end for the feat. However, I feel that there is one thing he did not focus on: the HEIGHT of the explosion itself.
The true measurements might even be bigger than that, given how the explosion could be seen from Karakura Town:
Ichigo and Aizen were miles away from Karakura Town when they fought, yet an explosion caused by Fragor could not only be seen from Karakura Town, but it was a towering pillar of light/smoke. Going by pixels, which was the same method used for the original calculation, the pillar is 120 x 371. This is being generous, because neither the top nor the bottom of the explosion can even be seen clearly, but based on the picture, it means tha the height of the explosion from ground level was three times the diameter.
Because of this, I believe that the depth being the same as the diameter is actually low-end, and that the depth of the crater is much deepr, and the crater itself possessing a potentially wider diameter.
Based on a 1:3.1 ration, that puts the height of the pillar of smoke/light at roughly 696 metres in height, not accounting for depth perception differences.
As a result, the crater depth is likely to be double the original assessment. That puts the total destructive power of the Fragor at 18,629,209.028571412 m^3. I would say that this puts Aizen's Fragor at roughly mid-end Town-level.
The article is free for edits for anyone wishing to do a proper calculation.
Again, my apologies for the sketchy nature of the calc. This is my first one after all.
NOTE: The calculations by pixel on the original are accurate.
While the feat has no destructive showings, due to being nullified before it could be fired, Aizen's Ultrafragor had the potential to be 100, if not a 1000-fold more powerful than Aizen's initial Fragor, and far more destructive. While the Fragor was just a small spiritual energy sphere, the Ultrafragor was a ring of energy around Ichigo's head. To be specific, FOUR RINGS OF ENERGY, with the rings growing larger the further they are from the center.
I can barely begin to calculate properly just how much energy in comparison is packed into the Fragor, but considering how Eldritch Aizen was incalculably more powerful than Yamamoto, someone whom Aizen himself acknowledge could destroy a town the size of Karakura with one of his techniques, if not a much wider area...
It would be a feat that dwarfed everything else seen in the manga. I think that Aizen's Ultrafragor might have been able to turn everything within at least a 20 kilometre radius into a smoking crater, and that is the low-end that I gave it.