Cone-Top Tank Volume Calculator
Work out the volume and capacity of a cone-top tank — a cylinder with a cone on top — in US gallons, imperial gallons, litres, cubic feet and cubic metres. Enter the cylinder diameter and height, the cone height and the cone-mouth diameter for the total capacity, or turn on partial fill to see how much liquid is in a part-full tank.
Tank volume calculator
What is a cone-top tank?
A cone-top tank is a cylindrical tank capped by a cone (more precisely a frustum) at the top, often with a smaller opening at the apex. The shape is common for covered process vessels and some silos. Its capacity is the cylinder plus the cone on top.
Cone-top tank volume formula
The total volume is the cylinder volume plus the cone (frustum) volume:
where R is the cylinder radius (half the cylinder diameter), H is the cylinder height, h is the cone height, and r is the radius of the cone mouth at the top. For the derivations and sources behind every formula on this site, see the methodology page.
How a cone-top tank fills (partial fill order)
Liquid fills a cone-top tank from the bottom upward, so the order is:
- The cylindrical section fills first, linearly with height, because its cross-section is constant.
- The cone on top fills last, once the cylinder is full. As the level rises into the cone, the cross-section narrows, so each additional inch of depth adds less volume.
This is the opposite order to a cone-bottom tank, which fills the cone first. The two have the same total volume for the same dimensions but different part-full readings.
Worked example
Take a cone-top tank with a cylinder diameter of 5 ft (so R = 2.5 ft), cylinder height H = 6 ft, cone height h = 3 ft, and cone-mouth diameter 1 ft (so r = 0.5 ft).
- Cylinder volume: π × 2.5² × 6 = 117.81 ft³.
- Cone (frustum) volume: (π × 3 / 3) × (2.5² + 2.5 × 0.5 + 0.5²) = π × 7.75 = 24.35 ft³.
- Total: 117.81 + 24.35 = 142.16 ft³ ≈ 1,064 US gallons (≈ 886 imperial gallons, ≈ 4,026 litres).
- Cylinder just full (liquid height = 6 ft): the filled volume equals the cylinder, 117.81 ft³ ≈ 881 US gallons — after this point the cone begins to fill.
Enter these numbers in the calculator above to confirm the figures and read imperial gallons, litres, cubic feet and cubic metres at the same time.
Units and gallons
This calculator reports cone-top tank capacity in US gallons, imperial (UK) gallons, litres, cubic feet and cubic metres at once, plus optional petroleum barrels. One US liquid gallon is 231 cubic inches ≈ 3.785 litres, while one imperial gallon ≈ 4.546 litres, so both are shown to avoid ambiguity. Enter inside dimensions for the closest estimate of liquid capacity.
Related tank shapes
For the opposite arrangement, see the cone-bottom tank volume calculator. For an all-cone body, use the conical tank volume calculator. For plain cylinders, see the vertical and horizontal cylindrical calculators, or the main tank volume calculator for every shape.
Frequently asked questions
How do you calculate the volume of a cone-top tank?
A cone-top tank is a cylinder with a cone (frustum) on top, so its total volume is the cylinder volume plus the cone volume: V = πR²H + (πh/3)(R² + Rr + r²), where R is the cylinder radius, H the cylinder height, h the cone height, and r the radius of the cone mouth at the top. Enter those dimensions above and the calculator returns the capacity in every common unit.
How does a cone-top tank fill?
From the bottom up, the cylindrical section fills first. Only once the cylinder is completely full does the cone on top begin to fill. This is the opposite order to a cone-bottom tank. The calculator follows this fill order across the cylinder-to-cone transition.
What is the difference between a cone-top and a cone-bottom tank?
They have the same total volume for the same dimensions, but they fill in opposite order. A cone-top tank fills the cylinder first and the cone last; a cone-bottom tank fills the cone first and the cylinder last. This page models the cone-top case; use the cone-bottom calculator for the other.
What units does the cone-top tank calculator output?
Results appear at once in US gallons, imperial (UK) gallons, litres, cubic feet and cubic metres, with an option to show petroleum barrels. One US liquid gallon is 231 cubic inches ≈ 3.785 litres; one imperial gallon ≈ 4.546 litres. Enter inside dimensions for the closest estimate of liquid capacity.