RC Reminder Calculator

Horizontal Cylinder Volume

A horizontal cylinder lies on its side — the circular cross-section is vertical and the length runs left to right. Total volume is the same as any cylinder: V = πr²L. But partial fill calculations are different from vertical tanks, and this tool handles both.

Horizontal Cylinder Volume

V = πr²L
L (Length) r

Total Volume of a Horizontal Cylinder

V = πr²L (total)

The total volume doesn't depend on orientation. A cylinder with radius r and length L holds V = πr²L whether it stands upright or lies on its side.

Example: A propane tank with diameter 60 cm (r = 30 cm) and length 120 cm. V = π × 900 × 120 = 339,292 cm³ = 339.3 litres.

Orientation only matters when you need to calculate partial fill — how much liquid is in the tank at a given depth.

Partial Fill in a Horizontal Tank

Partial fill is complex

When a horizontal cylinder is partially filled, the liquid forms a circular segment in the cross-section. The volume of liquid at depth h (measured from the bottom) is:

V = L × [r² × arccos((r−h)/r) − (r−h) × √(2rh − h²)]

This is more complex than a vertical tank (where partial volume is simply πr²h). The curved bottom means the fill rate is nonlinear — the tank fills slowly at the bottom and top, and fastest in the middle.

At h = r (half full), the volume is exactly πr²L / 2.

Applications of Horizontal Cylinders

r Propane • Fuel • Water

Horizontal cylindrical tanks are common for fuel storage (propane, diesel, gasoline), water transport, and industrial liquid storage. They're chosen over vertical tanks when head clearance is limited or when the tank needs to sit on a trailer.

Hot water cylinders in some countries are mounted horizontally. Tanker trucks carry liquid in horizontal cylindrical tanks. Underground fuel storage tanks at gas stations are typically horizontal.

The lower center of gravity of a horizontal tank makes it more stable during transport.

Frequently Asked Questions

Is the volume of a horizontal cylinder different from a vertical one?
No. Total volume is V = πr²L regardless of orientation. Only partial fill calculations differ.
How do I calculate how much liquid is in a horizontal tank?
Measure the liquid depth h from the bottom. Use V = L × [r² × arccos((r−h)/r) − (r−h) × √(2rh − h²)]. This calculator does it for you.
At what depth is a horizontal cylinder half full?
At h = r (the liquid level equals the radius). At this point, the cross-section is a semicircle and the volume is exactly half the total.
Why do fuel tanks lie horizontally?
Horizontal tanks have a lower center of gravity (safer for transport), fit under low clearances, and can be partially buried underground. They're also easier to load onto trailers.
How do I measure the liquid level in a horizontal tank?
Use a dipstick inserted vertically through the top of the tank. The wetted length is the liquid depth h. Some tanks have sight glasses or electronic level sensors.