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Freeform Pool Volume Calculator

Freeform pools have no repeating geometry, so volume is always an estimate. Measuring the maximum length and width and applying a 0.785 factor gets close enough for chemical dosing and pump sizing.

Freeform / Irregular pool with the measurements needed for a volume calculation

Calculate your freeform / irregular pool volume

1. Pick your pool shape

Any irregular shape with no repeating geometry. The result is an estimate.

2. Enter your measurements

Measure in feet or meters. You always get gallons and litres back.

3. Set your depth

Average depth = (shallow + deep) / 2.

Your pool volume result

Pool volume

14,469 gallons

54,772 litres

Cubic feet
1,934 cu ft
Cubic metres
54.8 m3
Surface area
352 sq ft
Average depth
5.50 ft
Pool shape
Freeform / Irregular
How we calculated this

Shape: Freeform / Irregular. Dimensions used: Maximum length 28 ft, Maximum width 16 ft. Depth: 3 ft shallow and 8 ft deep, averaged to 5.50 ft. Formula: Estimated volume = maximum length x maximum width x 0.785 x average depth. Conversion: cubic feet x 7.48 = US gallons, gallons x 3.785 = litres, cubic feet x 0.0283 = cubic metres.

This shape uses an average area factor, so treat the number as a close estimate rather than an exact volume.

How the freeform pool volume calculator works

Multiply maximum length by maximum width, then by 0.785 for the curved outline. Multiply that area by the average water depth.

For a very irregular pool, split it into two or three simple sections, calculate each one, and add the results together.

The formula

Estimated volume = maximum length x maximum width x 0.785 x average depth

Measure: Maximum length, maximum width, average depth.

Worked example

A freeform pool 28 feet long and 16 feet wide gives 28 x 16 x 0.785, which is 351.7 square feet.

At an average depth of 4.5 feet that is 1,582 cubic feet, roughly 11,838 gallons or 44,810 litres.

Tips before you measure

Take the two measurements at the widest and longest points of the water surface.

Check the estimate against your filter turnover time. If the water clears slower than expected, your real volume is probably higher.

Freeform / Irregular pool volume FAQs

How do I calculate an irregular pool?

Use maximum length times maximum width times 0.785, then multiply by average depth. Split very odd shapes into sections.

How exact is the answer?

Expect 5 to 10 percent either way. That is fine for chemicals, filters and heaters.

Is there a more precise method?

Yes. Refill through a meter and record the reading, or add a known dose of chemical and test the change.

Other pool shapes

Not quite the right outline? The main pool volume calculator covers all 20 shapes with the same units and formulas.