The result of your conversion between Btu and kiloton/cubic mile [US] appears here
To convert between Btu and Kiloton/cubic Mile [US] you have to do the following:
First divide 1055.0559 / ((0.45359237*2000)*1000)/(((0.0037854118/231)*1728*27)*5451776000) = 4847595.70117074
Then multiply the amount of Btu you want to convert to Kiloton/cubic Mile [US], use the chart below to guide you.
Symbol: Btu
No description
Symbol: kt/mi³
No description