Pool Volume Calculator | Volume and Fill Time by Shape
Find how many liters, US gallons, and cubic meters of water your pool, hot tub, or pond holds. The calculator covers rectangular, circular, oval, and L-shaped pools, and averages the shallow and deep ends so sloped-floor pools return a realistic capacity instead of a rough box estimate.
💡 About this tool
Almost every pool task starts with one number: how much water it holds. Chlorine dosing, shock treatments, and pH adjusters are all measured per volume, so a wrong capacity means you over- or under-treat the water. The same number tells you how long a hose will take to fill the pool and roughly what that will cost.
The math is straightforward: surface area multiplied by average depth gives the volume in cubic meters, then 1 m³ converts to 1,000 liters and 1 liter to 0.264172 US gallons. For pools that slope from a shallow to a deep end, averaging the two depths is the standard field approximation used by most pool-care guides. The L-shape mode splits the pool into two rectangles and adds the areas, which handles the most common non-rectangular backyard layout.
🧐 Frequently Asked Questions
Q. Are the gallons US or imperial? Output is in US gallons (1 liter = 0.264172 gallons). Most pool equipment and chemical labels use US gallons, so that is what the tool shows.
Q. My deep end is deeper than the shallow end. What do I enter? Enter each depth separately in the shallow and deep fields. The tool uses the average of the two. For a flat-bottom pool, put the same value in both.
Q. Where do I measure the diameter of a round pool? Measure the inside water width at the widest point, not the outer frame. Using the inner dimension keeps the result accurate.
Q. Why does my real fill differ from the number? Rounded corners, steps, and not filling all the way to the rim all introduce error. The figure is a geometric estimate from your dimensions, so treat it as a close guide rather than an exact reading.
Q. Why does the fill time show a dash? That appears when the flow rate or the volume is zero. Enter a positive flow rate and the estimated fill time is calculated.
📚 Fun Facts
A typical above-ground backyard pool around 3.6 m wide and 1.0 m deep holds roughly 10,000 liters. A 25-meter school pool (25 m × 13 m × 1.3 m average) climbs to about 420,000 liters. At a garden tap delivering 20 liters per minute, filling that 10,000-liter pool takes around eight and a half hours, which is why knowing the volume up front makes both the timing and the water bill far easier to plan.