How to calculate cylinder volume in liters
Use radius, height and π to estimate cylindrical tanks and containers.
What the calculation represents
Round drums and vertical tanks use the inside radius and liquid height. Keeping inch measurements is fine when the final cubic-inch value is converted rather than treated as liters.
- Reference formula
V = π × r² × h- Unit reference
- 1 L = 1,000 cm³ · 1 m³ = 1,000 L · 1 US gal = 231 in³ = 3.785411784 L
A practical workflow
- Measure the maximum and minimum inside diameters on perpendicular axes. If they are nearly equal, halve their average; if not, model the cross-section as an ellipse using π × (d₁/2) × (d₂/2).
- Measure vertical liquid height from the usable bottom to the operating fill line, excluding a neck or lid space.
- Square the radius and multiply by π and height while retaining full calculator precision.
- Convert cubic inches with 231 in³ per US gallon, or convert the metric result to liters, before applying headspace.
Calculate with your own values
Worked example
An 18-inch inside diameter and a 30-inch fill height give a 9-inch radius. The resulting 7,634 in³ is approximately 125.1 liters.
Cylinder height for a target volume
Enter the target liters and the full inside diameter of an upright cylinder.
Reading the answer correctly
A domed base, rounded shoulders or a fill line below the lid means the usable capacity is lower than a perfect cylinder.
Radius is squared, so diameter error has twice the approximate percentage effect on cross-sectional area. A careful diameter measurement usually improves the answer more than extra decimal places.
Checks before relying on the number
- The value squared in the formula is radius rather than the full diameter.
- Diameter and fill height are inside measurements expressed in a consistent unit.
- The formula describes an upright cylinder; a partly filled horizontal tank needs circular-segment geometry.
- An oval section retains both diameters instead of forcing one circular radius; domed ends and baffles are handled separately.
Sources and references
These references support the units, method, or limitations explained in this guide.
- NIST — SI Units: Volume
Definitions and exact relationships between liters and cubic units.
- OpenStax — Prealgebra 2e, §9.6
Ideal rectangular-solid, cylinder, sphere and cone formulas; not a certification of product capacity.
Keep the measured diameter, derived radius and liquid height together, then label the final figure as gross or working capacity.
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