↔ • Reviewed 2026-11-05

Horizontal Cylinder Partial-Fill Calculator

Calculate full capacity and liquid volume at any valid depth in a level horizontal cylinder.

Quick answer

The short version

Full volume is πr²L. Partial volume uses the circular-segment area at depth y multiplied by tank length.

V = L[r² arccos((r−y)/r) − (r−y)√(2ry−y²)]

Interactive tool

Calculate horizontal cylinder

Values convert through SI units; displayed digits are rounded only at the end.

V = L × circular segment area

r h
Result
—cm³

Complete the fields to calculate.

How the result changes

Calculated from the current dimensions
How the result changesComplete the calculator to display a graph.
Reserved advertising area

Checked example

Worked calculation

Result: For r = 1 m, L = 3 m and y = 1 m, the tank is half full: V = 1.5π ≈ 4.71239 m³.

01 • Guide

The fill curve is nonlinear

Equal increases in depth do not add equal volumes. Near the bottom the liquid is narrow; near mid-depth it spans almost the full diameter. The live graph shows this S-shaped relation.

Keep the full precision of intermediate values and round only the final display. This avoids compounding error when a derived radius or converted unit is used in another step.

02 • Guide

Endpoint handling

At depth zero the result is exactly empty. At depth 2r it is exactly full. The implementation handles those endpoints directly and clamps tiny floating-point roundoff inside the square root and arccosine.

The calculator validates physical limits before displaying a result. Blank or impossible inputs never produce a stale value, NaN or Infinity.

03 • Guide

Assumptions to verify

The tank must be level, have a constant circular section and use internal measurements. Elliptical sections, dished heads and tilted installation need a vessel-specific calibration chart.

Interpretation

How to use the result responsibly

The answer models an ideal geometric cylinder. Manufacturing tolerances, wall thickness, rounded ends, deformation, tank tilt and measurement uncertainty can all shift a real value. Use inside dimensions for capacity and outside dimensions for occupied space. For safety, compliance, dosing, structural or purchasing decisions, compare the estimate with drawings, calibration data or a qualified professional.

Dimensional checks help catch mistakes: a volume result must carry cubic units, an area result square units and a derived radius or height linear units. If changing one unit alters the represented physical size, a conversion step was missed.

Clear answers

Horizontal cylinder: common questions

Why is 25% depth not 25% volume?

Because the circular tank is narrower near the bottom than around its centre.

Can liquid depth exceed the diameter?

No. Valid depth is from 0 to 2r.

Continue exploring

Related cylinder tools