About 49.35 gallons
First find the volume of the tank in cubic inches. SInce it is a rectangular prism, the volume is length*width*depth:
Volume=19*30*20=11400 cubic inches
231 cubic inches = 1 gallon
So 11400 cubic inches=11400/231 or about 49.35 gallons
A tank of 21 inches wide, 8 inches deep and 59 inches long will hold 36 gallons of gas. These gallons refers to US gallons.
A tank this size holds up to 3,004(3,003.967872) gallons.
This tank will hold up to about 4,858(4,857.979293) gallons.
Assuming it is a rectangle, 56.232 imperial gallons
A tank with these dimensions has a volume of 150 cubic feet or 1,122.08 gallons.
About 38.82 gallons for every inch deep .
4 * 4 * 12 = 192 cubic feet = 1436.26 US gallons (approx)
I wonder if it might be 285 gallons!
A round tank 36 inches wide and 10 feet deep holds 528 gallons.
Please give the other dimensions 48"Long x ? Deep x ? High.
26 gallons for Short Box 34 gallons for Long Box
You would have to know how deep the tank is.