A practical guide to measuring pool dimensions for volume and planning calculations. This page explains the purpose of the tool and the information that matters before using a calculation.
Measuring a pool accurately is the first step toward estimating water volume and using many pool-care calculators. The measurements you need depend on whether the pool is rectangular, round, oval or an irregular shape.
Using outside dimensions, wall height or only the deepest point can lead to a misleading volume estimate. Measuring the water area and average water depth gives a more useful starting point.
Note: This guide is about swimming pool measurements. It is not a guide to measuring a billiards or pool table.
To measure a pool for a water-volume estimate, measure the inside water dimensions at the waterline rather than the outside wall. A rectangular swimming pool needs inside length and width; a round pool needs its inside diameter; and an oval pool needs its longest length and widest width. Record shallow and deep water depths, then use a representative average depth.
Small pool measurements vary by design. A compact inground pool, plunge pool, small swimming pool or small oval pool can have different lengths, widths, wall profiles and floor slopes. There is no single standard for small swimming pool measurements. Measure the actual water area instead of relying on a label such as “small”. If the floor slopes, take several depth readings and average them. Steps, benches and ledges reduce the water volume compared with a simple geometric estimate.
For pool owners asking how to measure gallons in a swimming pool or how to measure gallons in a pool, the key is to measure the waterline dimensions and average water depth rather than relying on a nominal pool size.
This guide is about measuring a swimming pool, not a billiards or pool table. Those use a different set of dimensions and search intent. Small inground pool measurements and small oval pool measurements can also vary widely, so use the actual water area.
For estimating water volume, use the inside dimensions at the waterline where possible. Outside measurements include wall thickness and may overstate the water area.
Measure water depth at representative shallow and deep points. For a simple slope, the average of those depths can be a starting estimate; complex floors may need more measurements.
Not usually. The waterline is often below the top of the wall, so measure the actual water depth.
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Find out how many gallons or litres of water your pool holds from its shape, size and average depth.
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