Casualty counts in late antiquity.

[Flavivs Aetivs]

My theory is that based on other battles we could extrapolate a possible count from the Battle of Chalons.

The First step would be finding the percentage of forces killed in all engagements with over 50,000 participants that were considered close victories or stalemates, and then divide the total number slain by the total number participated, to get a percentage.

Secondly you would have to average all of the percentages of said engagements.

Then you would have to apply it to the force count from the Battle of the Catalaunian plains. (about 60,000 Gallo-Romans vs. 70,000 Hun Confederation)