Pool Volume Calculator
Type your pool's length, width and the depth at each end, in metres or feet, and read how much water it holds in litres, US gallons and UK gallons at once. Rectangular pools open here; switch to Oval pool for an oval or round one, and the formula used is printed with the working under it.
Pool · l × w × (s + d) / 218,000 L · 4,755.1 US gal · 3,959.45 UK gal
A rectangular pool with a sloping floor: the average of the shallow and deep ends is the depth. One depth throughout: type it in both.
The formula is on the stage, and the working is the first row. Every answer here is one textbook formula with your numbers put in, printed so you can check it: a cylinder is π r² h, a sphere is (4/3) π r³, a pool is length times width times the average of its two depths. The horizontal tank uses the exact circular-segment formula for a partial fill, so half way up is exactly half and a quarter of the way up is less than a quarter, because the bottom of a circle is narrow. Conversions use exact definitions: a litre is 1,000 cm³, a US gallon is 231 cubic inches and a UK gallon is 4.54609 litres.
Common questions
- How is the volume of a pool worked out?
- Length times width times the average depth. A pool with a sloping floor is deeper at one end, so the tool asks for the depth at the shallow end and at the deep end and uses their average: l × w × (s + d) / 2. A 10 m by 5 m pool running from 1 m to 2 m deep is 10 × 5 × 1.5 = 75 m³, which the rows underneath give as 75,000 litres, about 19,813 US gallons and about 16,498 UK gallons.
- My pool is the same depth all over. What do I type?
- The same depth in both the shallow end and the deep end fields. The average of two equal numbers is that number, so a 10 m by 5 m pool 1.5 m deep throughout gives the same 75 m³ as one sloping from 1 m to 2 m.
- What about an oval or a round pool?
- Pick Oval pool. Type the full length across the long way, the full width across the short way, and the two end depths; the tool uses π × (l/2) × (w/2) × the average depth. A round pool has the same length and width: a 4.5 m round pool 1.2 m deep is π × 2.25 × 2.25 × 1.2, about 19.09 m³, or 19,085 litres.
- Why do I need the volume in litres or gallons?
- Because that is the number a chemical label or a pump's flow rate refers to. The volume is the amount of water in the pool; the tool gives it in litres, US gallons and UK gallons every time, and a US gallon is 3.785411784 litres while a UK gallon is 4.54609 litres, so make sure the label and the row match.
- Can I measure in feet?
- Yes. Switch the unit to ft and type the sides in feet; the volume comes out in cubic feet with the litres and gallons rows under it. A 20 ft by 10 ft pool from 3 ft to 6 ft deep is 900 cubic feet, which is 25,485 litres or about 6,732 US gallons, because a cubic foot holds 7.48 US gallons.
Volumes are computed from the formulas shown, exact for the dimensions you type; a horizontal tank's partial fill is the exact circular-segment result. A US gallon is 231 cubic inches and a UK gallon 4.54609 litres.