Pool Volume Calculator
Find the gallons in a rectangular pool from its dimensions.
Know your pool’s gallons
Almost everything about pool care — chlorine dosing, shock treatments, heater sizing — depends on knowing the water volume. This calculator turns a rectangular pool’s dimensions into gallons.
Enter length, width, and average depth, and it computes the cubic feet and converts to US gallons and litres. A 20 by 10 foot pool averaging 5 feet deep holds about 7,480 gallons.
Essential and private
The calculation runs in your browser, so nothing you enter is uploaded.
Frequently Asked Questions
How is volume converted to gallons?
The volume in cubic feet is multiplied by 7.48, the number of US gallons in a cubic foot.
What is average depth?
For a pool that slopes, average the shallow and deep ends. For a flat-bottomed pool, use the single depth.
Why do I need the gallons?
Pool chemical doses, heater sizing, and fill time all depend on the water volume.
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