Pool Volume Calculator
Calculate swimming pool volume in litres, US gallons, and cubic metres for rectangular, round, oval, or kidney-shaped pools.
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How to use this calculator
Average depth = (shallow depth + deep depth) / 2 for sloped-floor pools. Volume in litres = volume in m³ × 1000. US gallons = m³ × 264.172.
- 1
Select your pool shape.
- 2
Enter the pool dimensions in metres (length, width, or diameter as applicable).
- 3
Enter the shallow end and deep end depths.
- 4
Read the pool volume in litres, US gallons, and cubic metres.
Frequently asked questions
What formulas does the pool volume calculator use?
Rectangular: length × width × average depth. Round: π × (diameter ÷ 2)² × average depth. Oval: π × (length ÷ 2) × (width ÷ 2) × average depth. Kidney or freeform: the oval result multiplied by 0.85.
How is average depth worked out?
It is the shallow-end depth plus the deep-end depth, divided by two. That is exact only if the floor slopes in a straight line from one end to the other. A pool with a flat shelf and a sudden drop will deviate from it, so enter depths that represent the pool as a whole.
Which depth should I measure?
The tool volumes whatever depth you enter, so use the depth of water you expect, measured to the water line, not the full height of the pool wall. The calculator cannot know where the water will sit.
Which dimensions does each shape read?
Rectangular and oval pools use length and width. Round pools use only the diameter. The unused fields are ignored.
Are the gallons US or imperial?
US gallons, calculated as cubic metres × 264.172. The tool does not return imperial (UK) gallons.
How is the fill time calculated?
Litres divided by a fixed hose flow of 20 litres per minute, shown in hours. Your actual flow depends on water pressure, so measure it with a bucket and a timer and scale the figure.
How accurate is the kidney pool estimate?
It is a rough one. The 0.85 factor is a built-in approximation for a freeform outline relative to an oval of the same length and width. For a precise figure, measure the shape and split it into simpler sections.
Does the tool give chemical amounts?
No. It returns volume, average depth and fill time only. Treatment quantities should come from the product label, based on your pool’s volume.
Pool volume from shape, length, width and depth
Footprint area times average depth
Every shape in this calculator follows the same pattern: footprint area multiplied by the average depth. The footprint comes from the shape formula, and the average depth is the midpoint between the shallow and deep ends. Cubic metres are then converted to litres by multiplying by 1,000 and to US gallons by multiplying by 264.172. A final line estimates fill time on a 20 litres per minute hose.
How each shape is calculated
The table lists the footprint rule used for each shape and the fields it reads.
| Pool shape | Fields read | Footprint area |
|---|---|---|
| Rectangular | Length, width | length × width |
| Round | Diameter | π × (diameter ÷ 2)² |
| Oval | Length, width | π × (length ÷ 2) × (width ÷ 2) |
| Kidney / freeform | Length, width | Oval area × 0.85 |
Worked results
The table below gives calculator output for five pools. The default pool slopes from 1 m to 2 m; the 5 m by 3 m and round pools have a constant 1.2 m depth, and the oval and kidney pools share dimensions of 6 m by 3.5 m with depths from 0.9 m to 1.6 m.
| Pool | Litres | US gallons | m³ | Fill time at 20 L/min |
|---|---|---|---|---|
| Rectangular 8 m × 4 m, 1.0 to 2.0 m deep | 48,000 | 12,680 | 48.00 | 40.0 h |
| Rectangular 5 m × 3 m, 1.2 m deep | 18,000 | 4,755 | 18.00 | 15.0 h |
| Round 4.5 m diameter, 1.2 m deep | 19,085 | 5,042 | 19.09 | 15.9 h |
| Oval 6 m × 3.5 m, 0.9 to 1.6 m | 20,617 | 5,446 | 20.62 | 17.2 h |
| Kidney 6 m × 3.5 m, 0.9 to 1.6 m | 17,524 | 4,629 | 17.52 | 14.6 h |
What the comparison shows
The oval and kidney pools have identical dimensions and depths, and the kidney comes out about 3,100 litres smaller because of the 0.85 factor. The 8 m by 4 m rectangle has an average depth of 1.50 m, which is why it holds so much more than the shallower 5 m by 3 m pool. Fill times above 15 hours reflect the fixed hose flow in the tool; a stronger supply would shorten them.
Measuring for a reliable figure
Measure the internal water-surface dimensions rather than the outside edge of the shell, and take depths at the actual water line. Steps, benches and sloped corners reduce real volume slightly and are not modelled. If you plan to buy anything sized by volume, use the label and the manufacturer’s own instructions, and treat this figure as an estimate. For a shape the tool does not offer, such as an L-shaped pool, measure each section separately as a rectangle and add the volumes together. Entering the same depth in both fields is the correct way to describe a pool with a flat floor.
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Results are estimates for informational purposes only and do not constitute professional financial, medical, legal, or technical advice. Read full disclaimer →