GlenCalc

Tank volume calculator

A horizontal cylinder holds far less than you’d think when partly full; this works out the exact amount from the liquid depth.

Your answer

Liquid in the tank257.6 US gallons34.3% full
Full capacity752 US gallons

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How we worked it out

Updated as you change the numbers.

  1. Cross-section filled = r² arccos((r − h) ÷ r) − (r − h)√(2rh − h²); × length.
  2. 1 US gallon = 231 cu in.

Method and assumptions

The liquid in a horizontal cylinder fills a circular segment of its cross-section. Ends on real tanks are often domed, which adds a little volume; tank makers publish exact “strapping” charts.

Questions

How many gallons in a 4 ft × 8 ft horizontal tank at 18 in deep?

About 258 gallons of its 752 gallon capacity.

Sources

Method and figures checked on . Every worked answer on this page is covered by an automated test. Found a mistake? Tell us.

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