5000 tons

“You are quite something,” came Acqua’s voice amid the thunderous claps of clashing
longsword and blunt weapon. “To think you would bring two kilometers and five
thousand tons of magic circle to submission using feats of strength. But,” he continued,
“it looks to me as though your body has already passed its limit.”

- Toaru Majutsu no Index Volume 16, Chapter 3 Part 3