Comment by AbrahamParangi

https://en.m.wikipedia.org/wiki/Iceberg_A-68

A-68 was part of Larsen C, a section of the Larsen Ice Shelf. Scientists found the crack beginning to form in November 2016. Scientists assess that A-68 "didn't just break through in one clean shot, [but] it formed a lace-network of cracks first."[5] The resulting iceberg was around 175 km long and 50 km wide, 5,800 km² in area, 200 m thick and weighed an estimated one trillion tonnes.[8][5]

I’m not sure if Wikipedia is right here however because the linked sources have changed to remove mentions of mass.

That said we should be able to do a pretty dumb calculation. 1 km3 of water weighs ~1 gt.

5800 km2 x 0.2 km = 1160 km3

1160 km3 of ice x 0.9 (density of ice compared to water) x 1 gt / 1 km3 leaves us with a mass of about 1044 gt or around 1 trillion tons.

Edit: also, I am not able to find an original source for the mass of B-15 being in the few billions range