Question

How many gallons are in 161.25 sq ft

Answer 1

There are none. "Square foot" is a unit of area, not volume. 
Square feet are flat, and can't hold water.

If you meant to ask about 161.25 CUBIC feet, I can help you there:

(161.25 ft³) x (1,728 in³/ft³) x (1 gallon/231 in³) = 1,206.234 gallons (rounded)

Answer 2

I got 1206.23cubic feet when i tryed this problem hope this helped