A common question is "how much will 5 lbs of Kastolite 30 cover vs Mizzou Castable Plus?
The statement below is directly from Harbison Walker, the manufacturer.
Kast O' Lite 30 requires 92 pounds per cubic foot. This mean 5 pounds will cover 0.054 ft3 or 93.3 cubic inches.
MIZZOU requires 142 pounds per cubic foot. This means 5 pounds will cover 0.035 ft3 or 60.5 cubic inches.