Pool Volume Calculator

Multiply length by width by average depth, then multiply by 7.48 for a rectangular pool. A 16 by 32 foot pool averaging 5.5 feet deep holds about 21,000 gallons. Round pools use 5.9 instead of 7.48 and oval pools use 6.7. Enter your measurements above and the calculator does it for you.

Measure from the water line down to the floor at the shallow end, then again at the deep end. Add the two and divide by two to get the average depth. Do not measure to the top of the wall. The freeboard above the water line is not holding any water and including it overstates the volume.

Most residential inground pools hold 15,000 to 25,000 gallons. A 16 by 32 foot rectangle averaging 5.5 feet is about 21,000 gallons, which is the size most pricing and dosing charts assume. Above-ground pools are smaller, usually 5,000 to 15,000 gallons depending on diameter and wall height.

Every chemical dose is measured per 10,000 gallons. Chlorine, salt, acid, shock, algaecide and stabilizer are all sold with instructions that assume you know the number. Guessing means either wasting chemicals or under-treating the water. It also sets the pump run time and the filter size your pool needs.

Measure the length at the longest point and the width at the widest point, then use the freeform factor of 7.0 rather than 7.48. That accounts for the curved edges taking up less area than a rectangle of the same measurements. Select kidney or freeform above and the calculator applies it.

Yes, but not by much. An attached spa adds roughly 500 to 1,000 gallons if the water flows between the two. A tanning ledge is shallow, so it removes volume compared with a full depth pool. For chemical dosing the difference is inside the margin you already tolerate.

A 15 foot round pool with 48 inch walls holds about 5,000 gallons at a 42 inch water depth. With 52 inch walls and 46 inches of water it holds about 5,300 gallons. Above-ground pools are one depth throughout, so put the same number in both depth boxes.

In the United States pools are measured in gallons, and every chemical label sold here is dosed per 10,000 gallons. Liters are used in most other countries. One US gallon is 3.785 liters, so a 20,000 gallon pool holds about 75,700 liters. This calculator shows both.

It lands within a few percent for a normal pool with a steady slope, which is close enough for every chemical decision you will make. Steps, benches and irregular floors shift the true number slightly. If you need an exact figure, meter the water going in when the pool is filled.

A standard garden hose delivers about 9 gallons a minute, so a 20,000 gallon pool takes roughly 37 hours. Two hoses halve that. Water delivery by tanker fills the same pool in a few hours and costs more, and it is the case where an accurate volume figure genuinely matters.