How do I calculate rectangular pool volume?

Multiply water length by water width by average water depth. Use the actual water dimensions, not the outside dimensions of the pool structure.

How do I calculate a pool with a sloped bottom?

For a continuous uniform slope, average depth is shallow depth plus deep depth divided by two. Multiply that average depth by the water surface area.

How to Calculate Swimming Pool Volume

Use water dimensions, not outside construction dimensions

Measure the length and width at the water line and use water depth rather than the full structural depth. Keep every input in one unit system before calculating. Metric calculations normally use metres and produce cubic metres.

Rectangular pool

Volume = length × width × average water depth

For a pool with one continuous slope, average depth can be estimated as:

Average depth = (shallow depth + deep depth) ÷ 2

A 25 m × 10 m pool changing uniformly from 1.2 m to 1.8 m has an average depth of 1.5 m and an estimated volume of 375 m³.

Three-zone rectangular pool

When the pool has a level shallow platform, a sloped transition and a level deep platform, calculate the three sections separately:

Shallow-zone volume = shallow-zone length × width × shallow depth.
Transition volume = transition length × width × average of shallow and deep depths.
Deep-zone volume = deep-zone length × width × deep depth.

Add the three volumes. This avoids assuming that the entire pool bottom slopes continuously.

Circular and oval pools

Circular volume = π × radius² × average depth
Oval volume = π × half-length × half-width × average depth

Measure the water diameter for a circular pool. For an oval pool, measure the long and short water axes. If depth varies, use an appropriate average or divide the pool into separate zones.

Irregular pools

For a freeform pool, estimate the water surface area from a drawing, survey or divided grid, then multiply by average water depth. Splitting the plan into several simple shapes and adding their areas is usually more reliable than guessing one overall length and width.

Approximate volume = water surface area × average depth

Planning limitation: Steps, benches, ramps and curved walls can change the real water volume. For preliminary equipment selection, use measured drawings where available and preserve a reasonable margin.

From volume to circulation flow

Pool volume does not select a pump or filter by itself. Divide volume by the chosen turnover period to estimate the required circulation flow. Local requirements and the pool application can require a different turnover period.

Required circulation flow = pool volume ÷ turnover period

How to calculate swimming pool volume