Vertical Cylinder Tank Volume Calculator — Round Water Tank & Cylindrical Storage

Because every horizontal slice through a vertical cylinder is a circle of the same area. Fill one more inch and you add exactly πr² cubic inches of volume — always the same amount regardless of whether the tank is 10% or 90% full. This gives a perfectly linear dip chart where 25% depth = 25% volume, 50% = 50%, and so on. The gallons-per-inch constant (total gal ÷ total height) works for the entire range. Only dished heads at the very top break this linearity slightly — the head bulges outward adding more volume per inch near the top than the shell.

Most vertical tanks have either flat tops or some kind of head. Flat = 0 extra volume. Hemispherical head = (2/3)πr³ extra. 2:1 elliptical head = (1/3)πr³ extra (half a sphere). ASME F&D dished = roughly 0.0809 × diameter³. If your tank uses a dished head, include its height in your total tank height measurement but run the head formula separately — the extra volume only lives in the bulge, not down the straight wall. This calculator handles all four head types with a single toggle.

A vertical cylinder has a straight cylindrical body (the shell) between two flat or dished heads. A sphere has no straight shell — it is all curve. A capsule has a straight cylindrical body plus hemispherical heads (making it look like a medicine capsule). All three shapes have applications, but the straight shell of a vertical cylinder makes it far easier to fabricate and cheaper to ship. Spheres and capsules are used when pressure or volume-to-surface ratio matters more than cost. This page handles straight vertical cylinders; the sphere/capsule calculator on a dedicated page handles the curved variants.

Common sizes range from 200 gallons (36 dia × 28 H) for small domestic use up to 5,000 gallons (120 dia × 84 H) for farm or community storage. Above-ground residential tanks are usually 275–1,500 gallons; commercial process tanks start around 1,000 gallons and go well above 100,000 gallons. Metric sizes are common internationally: 500 L (52 dia × 24 H), 1,000 L, 2,000 L, 5,000 L. The presets above give you a quick starting point with correct dimensions.

If the tank is cylindrical and open-topped (common for atmospheric water cisterns) or covered with a simple flat lid, use 'Flat Heads'. If it is an ASME pressure vessel with a bulging top and bottom, the most common choices are 2:1 elliptical for medium-pressure or hemispherical for high-pressure. Measure the diameter and the bulge height — if the head's center sticks up 1/4 to 1/2 of the radius, that's 2:1 elliptical. If it sticks up a full radius, it's hemispherical. When in doubt, check the nameplate or manufacturer's spec sheet.