Use our handy calculator to find the unknowns in your tank equation. For instance, if you know the capacity of the tank you need in gallons and the height available in inches, enter these measurements in the appropriate fields. Then click on the "diameter or length" button to get the diameter in inches. (Enter height and diameter in inches, volume in gallons. For rectangular tanks, enter length in inches in the "Diameter" field and width in inches in the "Width" field.) The calculator will let you find the approximate volume of rectangular tanks, flat bottomed cylindrical tanks, tanks with a Standard or ASME dished bottom, and cone bottomed tanks; simply choose from the pull-down menu under "Tank Type." For tanks with a cone bottom, the four common choices for cone Angle a are available. Tank Type: Flat bottom Rectangular ASME Dish bottom Standard Dish bottom 15 deg. Cone bottom 30 deg. Cone bottom 45 deg. Cone bottom 60 deg Cone bottom Diameter in Inches (Length for Rectangular tanks): Height (Straight Side) in Inches: Width in Inches (Rectangular tanks only): Volume in Gallons: NOTES: For "Flat bottom" tanks (which are cylindrical) you can use the calculator to "What-if" your result by changing height, diameter or volume entries and clicking on the measurement you want recalculated. For "Rectangular" tanks, you can "What-if" in the same way, except that you must enter the additional dimension of width. Once you have calculated a "Flat bottom" tank, you can use the calculator to find the total volume of your tank with the addition of a cone or dished bottom. Choose the type of bottom from the "Tank type" pull-down menu and click on "volume." For tanks other than "Flat bottom" and "Rectangular," only volume will be recalculated accurately. Use the "clear" button and re-enter your specifications. Volumes of ASME and Standard dished bottoms are approximate. Volume results are rounded to the nearest gallon, height, diameter and width to the nearest inch.