Nasir Badar:
Founder & Construction Estimation Expert
With 10+ years in excavation, concrete, and site work, Nasir helps contractors and homeowners create accurate real-world estimates.
Calculate water volume in rectangular, cylindrical, and oval cisterns | US Gallons | Imperial Gallons | Liters | Cubic Feet
A cistern is a waterproof receptacle for holding water, typically used for rainwater harvesting, fire suppression, or backup water storage. This calculator helps determine the capacity of rectangular, cylindrical, and oval cisterns with support for feet+inches input, multiple unit outputs (US Gallons, Imperial Gallons, Liters, Cubic Feet), fill/empty time, and rainwater catchment estimation.
Getting your cistern size right isn’t just a calculation—it’s peace of mind. Too small, and you run out when you need it most. Too big, and you overspend for no reason. This simple calculator helps you quickly estimate capacity, so you can plan smarter, avoid guesswork, and make sure your water storage actually works in real life.
I've worked on countless rainwater harvesting projects where underestimating cistern capacity caused major problems - from running out of water during dry spells to installing tanks that were too small for the intended use. That's exactly why I built this cistern capacity calculator - to help homeowners, farmers, and engineers get their water storage calculations right the first time.
Whether you're planning a rainwater collection system, sizing a backup water supply for your home, or designing irrigation storage, knowing your exact cistern capacity in US Gallons, Imperial Gallons, Liters, or Cubic Feet changes everything. This calculator even estimates fill/empty times and rainwater catchment potential.
First, select your cistern shape: Rectangular, Cylindrical, or Oval. Enter the dimensions using feet and inches - the calculator automatically converts to decimal feet. Choose to calculate fill/empty times by entering your pump flow rate (GPM or GPH). For rainwater harvesting, enter your roof area, annual rainfall, and collection efficiency. Click calculate to see your cistern capacity in multiple units, fill/empty times, and annual rainwater catchment potential.