Cubic Feet of a Cylinder Calculator

Enter a cylinder's diameter and height to get its volume in cubic feet using V = πr²h, with results also shown per cylinder, in cubic yards, and in US gallons.

Quick Facts

Formula
V = π × r² × h
r is the radius (half the diameter) and h is the height or length, both measured in feet, so V comes out in cubic feet.
Conversions
27 ft³ = 1 yd³ · 1 ft³ ≈ 7.48 US gal
Used to show the same volume in cubic yards (concrete, soil) and US gallons (liquid capacity).

Your Results

Calculated
Total filled volume
-
Cubic feet, all cylinders at fill level
Volume per cylinder (full)
-
Cubic feet, one cylinder at 100% fill
Total volume
-
Cubic yards
Total volume
-
US gallons

Ready

Enter diameter, height, fill level, and quantity, then press Calculate.

Formula and method for Cubic Feet of a Cylinder

A cylinder's volume is V = π × r² × h, where r is the radius (half the diameter) and h is the height or length. This calculator takes the diameter you measure directly — the widest point straight across the circular face — halves it to get the radius, then applies the formula. Enter diameter and height in feet and the result comes out in cubic feet with no extra conversion step.

How the calculation works

Start with radius r = diameter ÷ 2. The full volume of one cylinder is π × r² × h. If you set a fill level below 100%, that full volume is multiplied by the fill fraction to model a partially filled tank or pipe. Multiply the per-cylinder result by the number of cylinders to get a total, then that total is converted to cubic yards (÷ 27) and US gallons (× 7.48052) automatically.

Common mistakes

  • Diameter vs. radius: the formula uses radius, not diameter. Entering the full diameter as the radius doubles it and quadruples the resulting volume (since radius is squared).
  • Mixed units: diameter and height must both be in feet for the result to come out in cubic feet. Convert inches to feet (÷ 12) before entering them.
  • Fill level left at the wrong value: a fill level of 100% assumes a completely full cylinder. For a partially filled tank, set the actual fill percentage or the total will overstate what's really inside.

Real-world applications

  • Sizing cylindrical water, fuel, or chemical storage tanks in cubic feet and gallons
  • Estimating concrete needed for a round column, footing, or post hole in cubic yards
  • Calculating capacity of pipes, silos, and drums for multiple identical units at once
  • Checking how much material a fill level (like a partly drained tank) actually holds versus full capacity

Frequently Asked Questions

What is the formula for the volume of a cylinder in cubic feet?
Volume equals V = π × r² × h, where r is the radius in feet (half the diameter) and h is the height or length in feet. Feeding feet into the formula produces cubic feet directly, with no extra unit conversion needed.
How do I convert cubic feet to gallons?
Multiply cubic feet by 7.48052, the number of US gallons in one cubic foot. A 10 cubic foot tank holds about 74.8 US gallons. This calculator applies that conversion automatically for the total filled volume.
How do I convert cubic feet to cubic yards?
Divide cubic feet by 27, since one cubic yard equals 3 feet × 3 feet × 3 feet, or 27 cubic feet. This conversion is common for concrete, soil, and mulch orders that are priced by the cubic yard.
What does the fill percentage input do?
Fill percentage scales the full cylinder volume down to represent a partially filled tank or pipe, such as a storage tank that is only 60% full. Leave it at 100% to calculate the cylinder's full capacity.

Related calculators