Pool, Tank & Aquarium Volume
Volume of a rectangular, round, oval or kidney pool or an upright tank, with shallow and deep ends, in litres, m³, US and UK gallons; fill time at your flow.
The volume of a pool or tank in every unit with exact conversion factors, the average depth used, the mass of water, and how long a hose or pump takes to fill it at the rate you enter.
Example: A 10 × 5 m pool sloping from 1.2 to 2.0 m holds 80 m³ = 80,000 L = 21,134 US gal = 17,598 UK gal; at 40 L/min it fills in 2,000 minutes.
Area times depth,
with the factors stated.
How each shape is measured, what average depth assumes, where the gallon figures come from, and why the brim-full number is an upper bound.
Shapes
Rectangle: length × width. Round: π d² ÷ 4 from the diameter. Oval: π × long axis × short axis ÷ 4 (an ellipse). Kidney: the common approximation 0.45 × (width A + width B) × length, labelled as an approximation because real kidneys vary. Upright cylinder: the same round area with the height as depth, for tanks and aquariums measured in the same way.
Depth
A single depth gives area × depth. With a shallow and a deep end the page uses their average, which is exact for a straight, even slope and an over-estimate for a hopper-bottom pool with a steep dive section — measure the breakpoints and split the pool into sections for that case.
Units
Volume in cubic metres is converted with exact factors: 1 US gallon = 3.785 411 784 L, 1 UK gallon = 4.546 09 L, 1 ft = 0.3048 m (NIST SP 811). Water mass uses 1 kg per litre. Fill time is litres ÷ the flow rate you enter — a garden hose or pump rate you measure with a bucket is the honest input.
What the number does not settle
This is the brim-full volume: normal water level sits below the coping, and steps, benches and rockwork displace water. Chemical dosing per volume is the product label's job. Inputs stay in your browser; the same four anonymous usage counts as the rest of the site apply.
SOURCES
Last reviewed 18 September 2026. How results are checked: How we verify.