Pool Fill Time Calculator

Common questions

How long does it take to fill a pool?

Divide the volume by the flow. A 10,000 gal pool at 10 gal/min is 1,000 minutes, which is 16 h 40 min, so a hose opened at 06:00 finishes at 22:40. The flow is what moves that number: the same pool at 6 gal/min takes 1 d 3 h 47 min, and at 16 gal/min it takes 10 h 25 min. That is a whole day of difference on one pool, which is why this page asks for a flow you measured rather than a figure it picked for you.

How do I measure the flow rate of my hose?

Put a bucket of known size under the hose, open the tap the way you will leave it, and time how long the bucket takes to fill. A 5 gal bucket filled in 30 s is 10 gal/min, because 5 gal in half a minute is 10 gal in a minute. There is a stopwatch on this page for it: press start, press stop when the bucket is full, and the seconds land in the field. Mains pressure, hose length and how far the tap is open all change the answer, so the measured number beats the quoted one every time.

How many gallons does my pool hold?

Measure the pool and let the page work it out. A rectangle is length times width times average depth: 32 by 16 ft running 3 ft at the shallow end and 8 ft at the deep end averages 5.5 ft, which is 2,816 cu ft, or 21,065 gal. A round pool is pi times the radius squared times depth, so 24 ft across and 4 ft deep is 1,809.56 cu ft, or 13,536 gal. An oval is the ellipse, pi over 4 times length times width times depth, and the same 32 by 16 ft outline with the same slope comes to 16,545 gal.

Do two hoses fill a pool twice as fast?

Only if both of them really deliver what you measured on their own. The page adds simultaneous flows before it divides, so 10 and 6 gal/min is 16 gal/min and a 10,000 gal pool drops from 16 h 40 min to 10 h 25 min. Two hoses on the same supply line often share the pressure, and each one then runs slower than it did alone. If the numbers matter, time a bucket on each hose while both are running.

Why is my pool taking longer to fill than the estimate?

The arithmetic assumes the flow you measured holds steady from the first minute to the last, and very little holds steady for 16 hours. A well delivers faster than it recovers, a shared main drops when the rest of the street is awake, and a hose turned off overnight moves the finish by exactly the hours it was off. That assumption is printed beside every answer here rather than buried under it, and the fastest way to check it is to time the bucket again halfway through.

Can I use litres and metres instead of gallons and feet?

Yes, and the whole form follows the switch. A 10 by 5 m pool sloping 1.2 m to 2 m averages 1.6 m deep, which is 80 m³, or 80,000 L, and at 40 L/min that is 2,000 minutes, or 1 d 9 h 20 min. Flow can be typed as gallons a minute, gallons an hour, litres a minute, litres a second or cubic metres an hour. The conversions are exact definitions rather than rounded constants: a US gallon is 231 cubic inches, which is 3.785411784 L.

What about a kidney, a figure eight or a freeform pool?

Use the oval, which is the closest of the three shapes here, and read the answer as a little high: a freeform shell curves inward where an ellipse does not. Three shapes are covered, a rectangle, a round pool and an oval, and each one prints its own formula next to the volume. A sloping floor is taken at the average of its two ends, which is exact for a floor that slopes evenly and generous for one with a flat shallow section, a short slope and a deep hopper at one end.