Cylinder Volume Tank Calculator

The Cylinder Volume Tank Calculator is a practical tool for determining the capacity of cylindrical tanks used for water storage, fuel, chemicals, and industrial liquids. This tool exists because cylindrical tanks are the most common tank shape in the world — from household water heaters to industrial storage facilities — and knowing their capacity is essential for planning, purchasing, and safety.

This calculator handles both vertical (standing) and horizontal (lying) tank orientations, and includes partial fill calculations so you can determine how much liquid is currently in the tank, not just the total capacity.

Whether you're sizing a rainwater collection tank, checking fuel reserves, or planning chemical storage, this calculator gives you volume in litres, gallons, and cubic meters instantly.

Horizontal tanks lie on their side — the circular cross-section is vertical and the length runs horizontally. Total volume is still V = πr²L (where L is the tank length).

Partial fill is more complex. The liquid level h (measured from the bottom of the circular cross-section) gives:

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

This formula accounts for the circular segment of liquid visible in the cross-section.

When selecting a tank, consider usable capacity vs total capacity. Most tanks can't be filled to 100% — you need air space for expansion, ventilation, or pump suction clearance. A typical usable capacity is 80–90% of total volume.

For water storage, 1 cubic meter = 1,000 litres = 264.17 US gallons. A household pressure tank holding 200 litres needs a cylinder roughly 60 cm diameter × 70 cm tall.

Fuel tanks, septic tanks, and industrial storage all use cylindrical shapes because they distribute pressure evenly and are efficient to manufacture.