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How to Calculate Water Tank Volume

Formulas for rectangular and cylindrical tanks, converting depth to litres, and automating the math with sensors.

Written by WellSenseOS Engineering Team · Published 2026-08-15 · 10 min read

Rectangular tanks

volume = length × width × water_depth

Use the same units throughout, then convert cubic metres to litres (× 1000).

Vertical cylinders

volume = π × (diameter / 2)² × water_depth

From sensor distance

water_depth = tank_height - measured_distance

Then apply the volume formula. Try the free tank volume calculator, or let WellSenseOS do it live.