Why bombing totals do not precisely locate unexploded bombs

Was the ordnance expended over Germany ever tallied, and how large is the uncertainty?

A theoretical total exists, but knowing which aircraft returned does not establish which lost aircraft bombed, where they released, or whether they reached the target.

There is a theoretical estimate of how much ordnance was expended over Germany, but the delivery record is incomplete. A thousand-bomber raid could establish how many aircraft returned without proving where every bomb was released. Some aircraft could bomb early and then be shot down. Others could reach the target, release their bombs and be lost on the return journey. Those different outcomes make aircraft-loss figures an imperfect guide to the amount of ordnance delivered.