ConverterHub

Pool Volume Calculator

Enter the pool length, width and average depth to get the water volume.

How it is calculated

All three inputs are in metres: length, width and the average depth of the water.

volume (m³) = length × width × depth
litres = m³ × 1000
US gallons = litres × 0.264172

Litres and gallons are rounded to whole numbers, cubic metres to two decimals. The tool treats the pool as a plain rectangular box, so it will not account for rounded corners, steps, a bench or a sloping floor except through the average depth you give it. If the floor slopes evenly from a shallow end to a deep end, the average depth is the shallow depth plus the deep depth, divided by 2. A zero or negative dimension gives no result, and neither does a depth above 100 m, which is far deeper than any real pool. The gallons are US gallons, not imperial ones.

Worked example

A pool is 10 m long and 5 m wide. It is 1.0 m deep at the shallow end and 1.7 m at the deep end, so the average depth is (1.0 + 1.7) ÷ 2 = 1.35 m. Volume: 10 × 5 × 1.35 = 67.50 m³. In litres: 67.50 × 1000 = 67,500 L. In US gallons: 67,500 × 0.264172 = 17,832 gal.

Try this example →

Common mistakes

  • Using the deep-end depth instead of the average depth. This overstates the volume of any pool that slopes, and chemical doses based on it will be too high.
  • Measuring the pool in feet and typing the numbers in unchanged. The fields are metres, so a 30 ft pool must be entered as about 9.1.
  • Entering the depth in centimetres (135) instead of metres (1.35). The tool refuses a depth above 100 m, so you get no result; a width or length typed in centimetres would instead be silently accepted and make the volume far too large.
  • Measuring the depth of the shell instead of the water level. Water normally sits some distance below the top edge, so measure the water.
  • Using the result for an oval, round or kidney-shaped pool. The tool assumes a rectangle, so these shapes will be overestimated.

About this calculator

The water volume of a rectangular pool is simply length × width × average depth, and since most residential pools slope from a shallow end to a deep end, the average depth — not the maximum depth — is the figure that gives an accurate total. That raw cubic figure is then converted into more familiar units: multiply cubic metres by 1,000 for litres, or by roughly 264.17 for US gallons.

Pool owners need this number for far more than curiosity — chemical dosing for chlorine shock treatment, algaecide, and pH adjusters is calculated per unit of water volume, so under- or overestimating the pool's size leads directly to under- or over-dosing the water. It is also used to estimate how long a garden hose will take to fill the pool, to size a pump and filter correctly for the water volume they need to circulate, and to estimate water costs before construction.

Enter the pool's length, width, and average depth, and the calculator returns the water volume in litres and US gallons.

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